GB2037799A - Substituted furopyridinones and furopyrazinones as color formers in pressure-sensitive and thermal imaging systems - Google Patents

Abstract

Substituted furopyridinones and furopyrazinones which are useful as color formers in pressure-sensitive carbonless duplicating systems and thermal marking systems are prepared by reacting diphenylamines with substituted a benzoyl (or 3-indolylcarbonyl)pyridinecarboxylic acids and substituted benzoyl (or 3-indolylcarbonyl)pyrazinecarboxylic acids, respectively.

Description

SPECIFICATION Substituted furopyridonones and furopyrazinines as color formers in pressure-sensitive and thermal imaging systems This invention relates to furopyridinones and furopyrazinones useful as color formers in pressure-sensitive carbonless duplicating systems and thermal marking systems, to processes for the preparation thereof and to pressure-sensitive duplicating systems and thermal marking systems containing the same.

Several classes of organic compounds of widely diverse structural types are known to be useful as color formers for carbonless duplicating systems. Among the more widely recognized classes are phenothiazines, for example, benzoyl leuco methylene blue; fluorans, for example 2'-anilino 6'-diethylaminofluoran; phthalides, for example, crystal violet lactone, and various other types of color formers currently employed in commercially acceptable carbonless duplicating systems. Typical of the many such systems taught in the prior art are those described in U.S. Patents 2,712,507, 2,800,457 and 3,041,289. Many of the color formers in the prior art, however, suffer one of more disadvantages such as low tinctorial strength, poor light stability, low resistance to sublimation and low solubility in common organic solvents.

U.S. Patent 3,775,424 and Belgian Patent 412,406 disclose furopyridinones and furopyrazinones for pressure-sensitive record material and Belgian Patent 862,217 discloses a series of phthalides useful as color formers in pressure-sensitive carbonless duplicating systems, thermal marking systems and hectographic or spirit-reproducing copying systems.

The present invention relates to a series of 7-(and 5-) (2-R3-4-NR4R5-phenyl) or(l-R,-2-R,-3- indolyl)-7- (and 5-)[(Y1-Y2-phenyl) (Y3-Y4-phenyl-a minoifu ro[3,4-b]-pyridine-5(7H)-[and 7(5H)-]ones, 3 (and 1-) (2-R3-4-NR4R5-phenyl) or (1-R-2-R7-3-indolyl)-3-(and 1-)[(Yt-Y2-phenyl)-(Y3-Y4- phenyl)aminojfuro[3,4-c]pyridine-1 (3H)-[and 3(1 H)-]-ones and 7-(2-R3-4-NR4R5-phenyl) or (1 -R,-2-R7- 3-indolyl)-7-[(Y1-Y2-phenyl) (Y3-Y4-phenyl)amino]furo[3,4-b]pyrazine-5(7H)ones which are useful as color formers in pressure-sensitive carbonless duplicating systems and thermal marking systems. The compounds develop colored images of good to excellent tinctorial strength; possess high resistance to sublimation, enhanced solubility in common organic solvents and have the particular advantage of excellent light stability.

More specifically, the compounds of the invention have the Formula l:

wherein A is a diva lent radical of the formula:

Y1, Y2, Y3 and Y4 are the same or different hydrogen, halo, lower alkoxy, alkyl having from 1 to 9 carbon atoms, phenyl-lower-alkyl or NR,R2 where RX is hydrogen or lower alkyl and R2 is hydrogen, lower alkyl, lower alkanoyl, phenylsulfonyl or lower-alkyl-substituted phenylsulfonyl; Z is a monovalent radical of the formula:

in which: R3 is hydrogen, lower alkyl, lower alkoxy, halo or di-lower-alkylamino; R4 is lower alkyl; Rs is lower alkyl or benzyl; R6 is hydrogen or non-tertiary alkyl having from 1 to 18 carbon atoms; and R7 is hydrogen, phenyl or non-tertiary lower alkyl.Preferably A is (a) or (d) and Z is (f) above.

Preferred compounds within the ambit of this particular embodiment are: 7-[4-(dimethylamino) phenyl]-7-(diphenylamino) furo [3,4-b] pyridine-5(7H)-one 5-[4-(dimethylamino) phenyl]-5-[diphenylamino)furo-[3,4-b] pyridine-7(5H)-one 7-[4-(dimethylamino) phenyl]-7-[bis (4-octylphenyl) amino]-furo [3,4-b] pyridine-5(7H)-one 5-[4-(dimethylamino) phenyl]-5-[bis (4-octylphenyl) amino]-furo [3,4-b] pyridine-7 (5H)-one 7-[4-(diethylamino)-2-methylphenyU-7-[bis(4-octylphenyl)aminojfurn[3,4b]pyridines(7H)one 5-[4-(diethylamino)-2-methyl phenyl]-5-[bis(4-octylphenyl)aminolfuro[3,4-b]pyridine-7 ( 5H)-one 7-(1 -ethyl-2-methyl-3-indolyl)-7-(diphenylam i no)fu ro-[3 ,4-b] pyridine-5(7 H)-one 5-(1-ethyl-2-methyl-3-indolyl)-5-(diphenylamino furo-[3,4-b] pyridine-7(5H)-one 7-(1-ethyl-2-methyl-3-indolyl)-5-[bis (4-octylphenyl)-amino] furo [3,4-b] pyridine-5(7H)-one and 5-( 1 -ethyl-2-methyl-3-i ndolyl)-5-[bis(4-octylphenyl)-amino]furo[3,4-b] pyridine-7(5H)-one.

One can prepare the compounds of Formula I hereinabove by a process which comprises reacting a pyridinecarboxylic acid having Formula ll:

Formula 11 with a diarylamine having Formula Ill:

Formula 111 in the presence of an anhydride of anhydride of an anhydride of an alkanoic acid having from 2 to 5 carbon atoms where in Formulas li and Ill, A, Z, Y1, Y2, Y3 andY4 have the previously given meanings.

One can also produce the compounds of Formula I by reacting a pyridinecarboxylic acid of Formula II with thionyl chloride, phosphorus oxychloride, phosphorus trichloride or phosphorus pentachloride followed by reaction of the resulting product with a diarylamine of Formula Ill in the presence of an organic base where in Formulas II and Ill, A, Z, Y, Y2, Y3 and Y4 have the previously given meanings.

The invention also deals with a pressure-sensitive carbonless duplicating system or thermal marking system containing a color-forming substance comprising a compound having Formula I as described above. A particular embodiment resides in a pressure-sensitive transfer sheet adapted for use with a receiving sheet having an electron accepting layer comprising a support sheet coated on one side with a layer of pressure-rupturable microcapsules, said micro-capsules containing a liquid solution of a color-forming substance comprising at least one compound having Formula I.Another embodiment resides in a heat-responsive record material comprising a support sheet coated on one side with a layer containing a mixture comprising at least one color-forming compound having Formula I and an acidic developer arranged such that application of heat will produce a mark-forming reaction between the color-forming compound and the acidic developer.

As used herein the term "halo" includes chloro, fluoro, bromo and iodo. Chloro is the preferred halo substituent because of the relatively low cost and ease of preparation of the required chlorosubstituted intermediates and because the other halogens offer no particular advantages over chloro.

However, the other above-named halo substituents are also satisfactory. The terms "lower-alkyl", "lower-alkoxy" and "di-lower-alkylamino" denote saturated acyclic groups having from 1 to 4 carbon atoms which may be straight or branched as exemplifi'ed by methyl, ethyl, propyl, isopropyl, butyl, sec butyl, isobutyl, tert-butyl, methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, isobutoxy, tert butoxy, dimethylamino, diethylamino, ethylmethylamino, dipropylamino, dibutylamino, isobutylmethylamino, di-tert-butylamino and the like.

The term "lower-alkanoyl" denotes saturated acyclic acyl groups having from 1 to 5 carbon atoms which may be straight of branched as exemplified by formyl, acetyl, propionyl, butyryl, isobutyryl, valeryl, 2-methyl-butyryl, isovaleryl, pivalyl and the like.

The term "phenyl-lower-alkyl" includes benzyl, 2-phenylethyl, 2-phenylpropyl, 3-phenylpropyl, 1- phenyl-butyl, 2,2-dimethyl-2-phenylethyl and the like. If desired, the phenyl group may contain a lower alkyl or lower alkoxy substituent.

As used herein, the term "alkyi having from 1 to 9 carbon atoms" denotes saturated monovalent straight or branched chain aliphatic hydrocarbon radicals including methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, amyl, 1 -methylbutyl, 3-methylbutyl, hexyl, isohexyl, heptyl, isoheptyl, octyl, isooctyl, 2-ethylhexyl, nonyl, 3-ethylheptyl and the like.

The term "non-tert-alkyl having from 1 to 1 8 carbon atoms" includes in addition to the abovenamed alkyl groups having from 1 to 9 carbon atoms, excluding, of course, any tertiary alkyl groups, saturated monovalent straight or branched chain aliphatic hydrocarbon radicals such as n-decyl, nundecyl, n-tridecyl, n-dodecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, 1 ,3,5-trimethylhexyl, 1 ,5-dimethyl-4-ethylhexyl, 5-methyl-2-butyl-hexyl, 2-propylnonyl, 2-butyloctyl, 2- pentanonyl, 1,2-di-methyltetradecyl and the like.

Anhydrides of alkanoic acids of 2 to 5 carbon atoms include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, isovaleric anhydride, a-methylbutyric anhydride, pivalic anhydride and the like.

Acetic anhydride is preferred because of its low cost and high reactivity. However, the other above-named anhydrides are also satisfactory.

In the usual practice of the first process described above, one reacts approximately equimolar amounts of the pyridinecarboxylic acid of Formula II and the diarylamine of Formula Ill in the presence of an anhydride of an alkanoic acid having from 2 to 5 carbon atoms such as acetic anhydride with or without an inert diluent at a temperature of about OOC to 1 000C. for approximately 10 minutes to 72 hours. The reaction is usually carried out in the absence of an inert diluent at about 2O500 C. for approximately 0.5 to 2 hours.The produce thus obtained can be isolated by filtration if it is insoluble in the reaction medium or by dilution of the reaction medium with a miscible solven tin which-the product is insoluble such as a lower alkanol or low molecular weight hydrocarbon, for example, isopropyl alcohol or hexane, ora mixture of these in order to effect precipitation of the product Alternatively, the reaction mixture can be poured into aqueous base such as dilute ammonium hydroxide, sodium hydroxide, sodium carbonate or sodium bicarbonate and the product extracted with an organic solvent such as benzene or toiuene followed by evaporation of the organic solvent leaving the product as a residue. The product once isolated, can be purified by conventional means such as trituration or recrystallization from a suitable solvent.

In the above reaction the diarylamine of Formula Ill serves as a basic catalyst. However, if desired an additional organic base such as pyridine, collidine, tri-lower-alkylamines, urea and the like can be employed. Ordinarily pyridine and urea are preferred.

In the usual practice of the second process described above, a compound of Formula I can be prepared in two steps which comprise, first, reacting a pyridine carboxylic acid of Formula II with an excess of an inorganic acid chloride such as thionyl chloride, phorphorus oxychloride, phosphorus trichloride or phosphorus pentachloride with or without an inert diluent such as benzene, toluene, chloroform, 1,2-dichloroethane or N,N-dimethylformamide at 2080aC. for about 0.5 to 2 hours, followed by a reaction by the resulting product which, while not having been isolated, is presumed to be a chloride having Formula IV::

Formula IV in which A and Z have the previously given meanings, with a diarylamine of Formula Ill hereinabove in an inert solvent in the presence of an organic base such as pyridine, collidine, tri-lower-alkylamines or urea at a temperature in the range of 0--800C. for about 1 to 48 hours. The product can be isolated and purified in conventional fashion.

The pyridinecarboxylic acids and pyrazinecarboxylic acids of Formula II hereinabove which are required as starting materials in the preparation of the final products of Formula I are generally known, for example, as disclosed in U.S. Patents 3,936,564 and 3,775,424 and Japanese Patent Publications 73/8727, 73/3205 and 73/8729.Those pyridine-carboxylic acids and pyrazinecarboxylic acids which are novel can be prepared in accordance with the procedures described for the preparation of the known compounds, i.e., by reacting an anhydride having Formula V:

Formula V with an appropriate aniline of Formula VI or an indole of Formula VII::

wherein A, R3, R4, R5, R6 and R, in the above formulas have the previously given meanings, in the presence of a Lewis acid, for example, aluminum chloride or zinc chloride, and with a diluent such as benzene, chlorobenzene or o-dichlorobenzene at a temperature of about 0--1000C. The reaction is conveniently carried out in benzene in the presence of aluminum chloride at about 0--250C. The more reactive indoles (Formula VII) can be reacted with the anhydrides (Formula V) in the absence of a Lewis acid by simply heating the reactants together in an inert solvent at about 80-1 500 C.

It will, of course, be appreciated that reaction of the inherently unsymmetrical anhydrides of Formula V wherein A is:

with an aniline of Formula VI or an indole of Formula VII can produce isomers or a mixture of isomers of Z-CO-pyrimidine-carboxylic acids (Formula II). For example, reaction of 2,3-pyridinedicarboxylic anhydride (Formula Va hereinbelow) with an aniline or an indole of Formula VI or VII, respectively, (Z-H hereinbelow) can produce either a 2-(Z-CO)-3-pyrimidine-carboxylic acid (Formula Ila) or a 3-(Z-CO-2- pyrimidine-carboxylic acid (Formula llb) or a mixture of these.It will, of course, be appreciated that the ratio of isomers obtained will depend on various reaction conditions such as temperature, solvent, catalyst and the relative solubility of the isomers in the reaction medium. Ordinarily, when carried out as described herein the reaction produces a mixture of isomers with the 2-(Z-CO)-3-pyridinecarboxylic acid (Formula Ila) predominating in the isolated product.If desired, the mixture of isomeric Z-COpyridinecarboxylic acids can be separated by conventional means such as selective precipitation at different pH, fractional crystallization or chromatography and each of the individual isomers Ia and llb can then be reacted with an appropriate diarylamine of Formula Ill to produce a furo[3,4-b]pyridine5(7H)-one of Formula la and a furo-[3,4-b]pyridine-7(5H)-one of Formula Ib, respectively. It is generaly preferred however, to simply react the isolated mixture of isomeric Z-CO-pyridinecarboxylic acids of Formulas Ila and llb with a diarylamine to produce an isomer mixture of furopyridinones of Formulas la and Ib which can be separated by conventional means if desired. However, since both isomers are useful as color formers it is economically advantageous to simply use the isolated mixture thereof in the practice of this invention.

In general. it has been found that the reaction of 2,3-pyridinedicarboxylic anhydride with an indole of Formula VII in the manner described herein produces a mixture of isomers of Formulas Ila and llb (Z is

in which isomer Ila predominates in the isolated product by a factor greater than about 7. Moreover, it has been further observed that the more abundant isomer (i.e. lla) is also the more reactive. Accordingly, subsequent reaction of the isomeric mixture of Ila and llb with a diarylamine of Formula III produces almost exclusively furo[3,4-b]-pyridine-5(7H)-one (Formula la) with isomer Ib being observed only in trace amounts.

The reaction of 2,3-pyridinedicarboxylic anhydride with an aniline of Formula VI in accordance with the procedures described herein also produces a mixture of isomers of Formulas Ila and llb (Z is

and although isomer Ila again predominates in the isolated product, significant amount of isomer lib are also obtained. Thus, although isomer Ila is more reactive, a sufficient concentration of the less reactive llb is present in the mixture to afford upon reaction with a diarylamine of Formula Ill a mixture of isomeric furo[3,4-b]pyridinones of Formulas la and Ib in which isomer la is predominant and isomer Ib is present in minor, but significant amounts.

In like fashion, reaction of 3,4-pyridinecarboxylic anhydride (Formula Vb hereinbelow) with an aniline of Formula VI or an indole of Formula VII (Z-H hereinbelow) produces a mixture of 3-(Z-CO)-4pyridinecarboxylic acid (Formula lIc) and 4-(Z-CO)-3-pyridinecarboxylic acid (Formula lid). The mixture is in turn reacted with a diarylamine of Formula Ill to produce an isomeric mixture of furo[3,4-c]pyridine 1 (3H)-òne (Formula Ic) and furo[3,4-c]pyridine-3( 1 H)-one (Formula Id).

The diarylamines of Formula Ill which are also required as starting materials in the processes of the invention, belong to a well-known class of compounds and are either commercially available or readily obtained by conventional procedures well known in the art.

The novel compounds of Formula I hereinabove are essentiaily colorless in the depicted form.

When contacted with an acidic medium, for example, silica gel, or one of the types ordinarily employed in pressure-sensitive carbonless duplicating systems such as silton clay or phenolic resins, the compounds of Formula I develop a yellow to black colored image of good to excellent tinctorial strength and possessing resistance to sublimation, xerographic copiability and especially excellent light stability.

The compounds are thus highly suitable for use as colorless precursors, that is, color-forming substances in pressure-sensitive carbonless duplicating systems. Compounds which produce a yellow to red color can be used as toners in admixture with other colorformers to produce images of a neutral shade which desirably are readily copiable by xerographic means.The compounds of Formula I wherein one or more Y1, Y2, Y3 andY4 are alkyl of 1 to 9 carbon atoms have excellent solubility in common and inexpensive organic solvents, such as odorless mineral spirits, kerosene, vegetable oils and the like thereby avoiding the need for more expensive and specialized solvents such as polyhalogenated or alkylated biphenyls which have ordinarily been used to prepare micro-encapsulated solutions of the color formers of the prior art.

The compounds of this invention may be incorporated in any of the commercially accepted systems known in the carbonless duplicating art. A typical technique for such application is as follows: solutions containing one or more colorless precursor compounds of Formula I optionally in admixture with other color formers in suitable solvents are microencapsulated by well-known procedures, for example, as described in U.S.Patent 3,649,649. The microcapsules are coated on the reverse side of a transfer sheet with the aid of a suitable binder and the coated transfer sheet is then assembled in a manifold with the microcapsule-coated side in contact with a receiving sheet coated with an electronic accepting substance, for example, silton clay or a phenolic resin. Appiication of pressure to the manifold such as that exerted by a stylus, typewriter or other form of writing or printing causes the capsules on the reverse side to rupture. The solution of the color former released from the ruptured microcapsules flows to the receiving sheet and on contact with the acidic medium thereon forms a yellow to black image of good tinctorial strength and of superior light stability. It is, of course, obvious that variants of this mode of application can be utilized.For example, the receiving sheet in a manifold can alternatively be coated with the subject compounds and the acidic developing ayent can be contained in microcapsules applied on the reverse side of the top sheet in the manifold; or the receiving sheet can be coated with a mixture containing both the acidic developing agent and the microencapsulated color former.

It has also been found that when the compounds of Formula I are intimately mixed with an acidic developer of the type generally employed in thermal papers such as described in U.S. Patent 3,539,375, that is, papers which produce a colored image when contacted with a heated stylus or heated type, for example bisphenol A, heating of the mixture produces a colored image of varying shades from yellow to purple depending on the particular compound of the invention employed. The ability of the compounds of Formula I to form a deep color when heated in admixture with an acidic developer such as bisphenol A makes them useful in thermal paper marking systems either where an original or duplicate copy is prepared by contacting the thermal paper with a heated stylus or heated type in any of the methods generally known in the art.

The molecular structure of the compounds of this invention were assigned on the basis of the modes of synthesis, elemental analysis and study of their infrared, nuclear magnetic resonance and mass spectra. The identity and relative abundance of individual isomers in mixtures of Z-COpyridinecarboxylic acids and furopyridinones were determined on the basis of thin layer chromatography and nuclear magnetic resonance spectroscopy using the shift reagent tris(dipivalomethanato)europium (Ill) [Eu(DPM)3].

The following examples will further illustrate the invention without, however, limiting it thereto.

EXAMPLE 1 A. To a mixture containing 10 g. of 2,3-pyridinedicarboxylic anhydride and 26 g. of N,N-dietyl-mphenetidine in 100 ml. of benzene was added 27 g. of aluminum chloride. After stirring at about 400 C.

for 20 hours the reaction mixture was filtered and the solid obtained was added to 800 ml. of ice-water.

The resulting precipitate was collected, washed with water and then dissolved in 600 ml. of 10% aqueous sodium hydroxide. After filtering to remove a small amount of insoluble material, the basic aqueous solution was acidified with dilute hydrochloric acid to pH 6. The resulting precipitate was collected, washed with water and dried to give 13.4 g. of product. The filtrate was set aside for further work-up as described in part B hereinbelow. The 1 3.4 g. of solid material was again dissolved in aqueous base. The resulting solution was filtered and the filtrate adjusted to pH 6 with dilute hydrochloric acid. The pale yellow solid which precipitated was collected, washed with water and dried.

The dried material was then slurried in a mixture of 100 ml. of toluene and 10 ml. of ethanol and the pale yelow solid was collected and dried to give 2.6 g. of 3-[4-(diethylamino)-2-ethoxybenzoyl]-2pyridinecarboxylic acid, m.p. 264-2700C. (dec.).

B. The filtrate which had been set aside was further acidified to pH 2. The resulting light yellow precipitate was collected, washed with water and dried to give 6.0 g. of product. Recrystallization from ethanol-toluene afforded 4.0 g. of 2-[4(diethylamino)-2-ethoxybenzoyl]-3-pyridine-carboxylic acid, m.p. 209--21 OOC.

C. A mixture containing 1.7 g. of 2-[4-(diethylamino)-2-ethoxybenzoyl]-3-pyridinecarboxylic acid, 1.0 g of diphenylamine, 0.5 g. of urea and 20 mi. of acetic anhydride was stirred 20 hours at room temperature. Almost immediateiy after the reactants had been combined, the mixture became deep red in color indicating a rapid reaction. The reaction mixture was poured into 300 ml. of toluene and 200 ml. of 5% aqueous ammonium hydroxide. The toluene layer was separated, washed successively with water and saturated aqueous sodium chloride and then passed through a short column of silica gel. The desired product was eluted from the silica gel column with acetone.Evaporation of the acetone under vacuum and crystallization of the residue from 2-propanolhexane afforded 1.7 g. of 7-[4-(diethylamino) 2-ethoxyphenyl]-7-(diphenyiamino)furo[3,4-b]pyridine-5(7H)-one as a light tan solid, m.p.

183.5-1 850C. This product produced a red image on acid clay and phenolic resin.

D. Following a procedure similar to that described in part C above, by employing 2.5 g. of 3-[4 (diethylamino)-2-ethoxybenzoyl]-2-pyridinecarboxylic acid, 1.5 g. of diphenylamine, 0.5 g. of urea and 30 ml. of acetic anhydride and allowing the reaction mixture to stir at room temperature for 2 days (the lack of a color change in the reaction mixture after 5 hours indicated a slow reaction), there was obtained 0.2 g. of 5-[4-(diethylamino)-2-ethoxyphenyl]-5-(diphenylamino)furo[3,4-b]pyridine-7(5H)- one as a brown, gummy material. This product produced a red image on acidic clay andphenolic resin.

EXAMPLE 2 Following a procedure similar to that described in Example 1 C hereinabove, but employing 1.7 g.

of 2-[4-(diethylamino)-2-ethoxybenzoyl]-3-pyridinecarboxylic acid, 1.1 g. of 3-chloro-N-phenylaniline, 0.5 g. of urea and 20 ml. of acetic anhydride, there was obtained 1.0 g. of 7-[(3 chlorophenyl)phenylamino]-7-[4-(diethyla mino)-2-ethoxyphenyl]f u ro[3,4-b]pyridine-5(7H)-one as a light tan solid, m.p. 130-131 OC. This product produced a red image on acidic clay and phenolic resin.

EXAMPLE 3 A mixture containing 2.0 g. of an isomer mixture comprising 3-[4-(diethylamino)-2methyibenzoyl]-2-pyridinecarboxylic acid and 2-[4-(diethylamino)-2-methylbenzoyl]-3- pyridinecarboxylic acid, 0.81 g. of 4,4'-bis(dimethylamino)-diphenylamine, 6 ml. of acetic anhydride and 0.5 ml. of pyridine was stirred 1 hour at room temperature and then poured into 200 ml. of 5% aqueous ammonium hydroxide and 100 ml. of toluene. The toluene layer was separated, washed with water and saturated aqueous sodium chloride and evaporated to dryness under vacuum.The residue was slurried in a minimum amount of acetone to give 0.5 g. of an isomer mixture comprising 7-[4-(diethylamino)-2 methylphenyl]-7-{bis[4-ldimethylamino)phenyi]aminolfuror3,4-b]pyridine-5(7H)-one and 5-[4 (diethyla mino)-2-methyl phenyl]-5-j bis[4-(d i methylamino)phenylja mino)furn[3,4-bjpyridine-7( 5H)-one, as a light green solid, m.p. 184-1 860C. A chloroform solution of the product contacted with acidic clay or phenolic resin developed a black image.

EXAMPLE 4 A. A mixture containing 3.2 g of an isomer mixture comprising 2-[4-(diethylamino)-2 methylbenzoyl]-3-pyridinecarboxylic acid and 3-f4-(diethylamino)-2-methylbe nzoylj-2- pyridinecarboxylic acid, I05 g. of 4,4'-dioctyldiphenylamine, 6 ml. of acetic anydride and 1.1 ml. of pyridine was stirred 45 minutes at room temperature.After diluting the reaction mixture with 6 ml. of 2-propanol and 3 ml. of hexane, the product was collected, washed with 2-propanol and dried to give 1.5 g. of an isomer mixture comprising 7-[4-(diethylamino)-2-methylphenyl]-7-[bis-(4-octylphenyl) amino]fu ro[3,4-b]pyridine-5(7H)-one and 5-[4-(diethylamino)-2-methylphenyl]-5-[b octylphenyl)amino]furo[3,4-b]-pyridine-7(5H)-one as a light purple solid, m.p. 1 94--1 95 OC. (dec.).

The filtrate was poured into 5% aqueous ammonium hydroxide and the product was extracted with toluene. The organic extracts were washed with water and saturated aqueous sodium chloride and evaporated to dryness under vacuum. Crystallization of the residue from 2-propanol afforded 1.0 g. of additional product as a white solid. A toluene solution of the product contacted with acidic clay or phenolic resin developed a reddish-purple image.

B. To a mixture containing 1.4 g. of an isomer mixture comprising 2-[4-(diethylamino)-2methylbenzoyl]-3-pyridinecarboxylic acid and 3-[4-(diethylamino)-2-methylbenzoyl]-2pyridinecarboxylic acid, 1.0 ml. of thionyl chloride and 60 ml. of N,Nifimethylformamide was added a solution containing 1.84 g. of 4,4'-dioctyldiphenylamine and 0.5 ml. of pyridine in 40 ml. of N,Ndimethylformamide at room temperature. After stirring for one hour, the reaction mixture was poured into 5% aqueous ammonium hydroxide. The precipitate was collected, washed with water and air-dried.

The solid was then slurried in a mixture of 30 ml. of hexane and 10 ml. of 2-propanol and filtered to give 1.03 g. of product essentially identical to the product of part A above.

C. A mixture containing 3.1 3 g. of an isomer mixture comprising 2-[4-(diethylamino)-2methylbenzoyl]-3-pyridinecarboxylic acid and 3-[4-(diethylamino)-2-methylbenzoyl]-2- pyridinecarboxylic acid, 3.94 g. of 4,4'-dioctyldiphenylamine, 6 ml. of acetic anhydride, 6 ml. of acetic acid and 0.75 g. of urea was stirred 2 hours at room temperature, then poured into 5% aqueous ammonium hydroxide and extracted with toluene. The organic extract was washed with water and saturated aqueous sodium chloride and evaporated to dryness. The residue was analyzed by thin layer chromatography and infrared spectroscopy and shown to contain the desired product identical to the product of part A above.

D. The reaction of part C above was carried out in the absence of urea. The reaction mixture was poured into 5% aqueous ammonium hydroxide and extracted with toluene. The toluene extract was washed with water, saturated aqueous sodium chloride and evaporated to dryness. The residue was analyzed by thin layer chromatography and infrared spectroscopy and shown to contain the desired product identical to the product of part A above.

EXAMPLE 5 Following the procedure similar to that described in Example 4A but employing 1.6 g. of an isomer mixture comprising 2-[4-(diethylamino)-2-methylbenzoyl]-3-pyridineca rboxylic acid 3-[4 (diethylamino)-2-methylbenzoyl]-2-pyridinecarboxylic acid, 0.6 g. of 4-isopropoxy-N-phenylaniline, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 0.7 g. of an isomer mixture comprising 7-[4-(diethylamino)-2-methylphenyl]-7-[4-isopropoxyphenyl)phenylamino]furo[3,4-b]-pyridine-5(7Hl- one and 5-[4-(diethylamino)-2-methylphenyl]-5-[(4-isopropoxyphenyl)-phenylamino]furo[3,4- b]pyridine-7(5H)-one as a white solid, m.p. 180-181 OC. A toluene solution of the product contacted with acidic clay or phenolic resin developed a reddish-purple image.

EXAMPLE 6 Following a procedure similar to that described in Example 4A but employing 1.55 g. of an isomer mixture comprising 2-[4-(diethyla mino)benzoyl]-3-pyridi necarboxylic acid and 3-[4-(diethylamino) benzoyl]-2-pyridinecarboxylic acid, 1.2 g. of 4-isopropoxy-N-phenylaniline, 0.5 ml. of pyridine and 6 ml of acetic anhydride there was obtained 0.7 g. of an isomer mixture comprising 7-[4-(diethyl amino)-phenyl]-7-[(4-isopropoxyphenyl)phenylamino]furo[3,4-b]-pyridine-5(7H)-one and 5-[4-(diethyl amino)phenyl]-5-[(4-isoprnpoxyphenyl)phenylamino]furn[3A-bjpyridinej-7(5H)-one as white solid, m.p. 173-1 750C. A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

EXAMPLE 7 Following a procedure similar to that described in Example 3 but employing 1.55 g. of an isomer mixture comprising 2-[4-(diethylamino)-benzoyl]-3-pyridinecarboxylic acid and 3-[4-(diethylamino) benzoyl]-2-pyridinecarboxylic acid, 1.33 g. of 4,4'-(dimethylamino)diphenylamine, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 0.83 g. of an isomer mixture comprising 7-[4 (diethylamino)-phenyl]-7f bis[4-(dimethyla mi no)phenyl]amino1furo[3,4-bj-pyridine-5(7H )-one and 5-[4 diethylamino)phenyl]-5!bis[4-(dimethylamino)phenyl]aminolfuro[3,4-b]-7(5H)-one as a light graybrown solid, m.p. 1 C. (dec.).A toluene solution of the product contacted with acidic clay or phenolic resin developed a dark-brown image.

EXAMPLE 8 A mixture containing 0.2 g. of an isomer mixture comprising 2-[4-(diethylamino)benzoyl]-3pyridinecarboxylic acid and 3-[4-(diethylami no)benzoyU-2-pyridinecarboxylic acid, 0.1 5 g. of diphenylamine and 5 ml. of acetic anhydride was stirred 3 hours at room temperature. The reaction mixture was poured into 100 ml. of toluene and 100 ml. of 5% aqueous ammonium hydroxide. The toluene layer was separated washed successively with water and saturated aqueous sodium chloride and evaporated to dryness under vacuum.Crystallization of the residue from hexane afforded 0.1 g. of an isomer mixture comprising 7-[4-(diethylamino)phenyl]-7-(diphenylaminoÇfuro[3,4-b]pyridine-5(7H)- one and 5-[4-(diethyíamino)phenyl]-5-(diphenylamino)furo[3,4-b]pyridine-7(5H)-one as a tan solid, m.p. 1 68-1 690C. This product produced a deep orange image on acidic clay and phenolic resin. EXAMPLE 9 A mixture containing 2.7 g. of an isomer mixture comprising 2-[4-(dimethylamino)benzoyl]-3pyridinecarboxylic acid and 3-[4-(dimethylamino)benzoyl]-2-pyridinecarboxylic acid and 25 ml. of acetic anhydride was heated to 500C. After a solution formed, 1.7 g. of diphenylamine was added. The mixture was stirred 2.5 hours at 250C., 500C. for 1.5 hours and then cooled to 50C.The resulting solid was filtered and washed with isopropanol to give 1.3 g. of an isomer mixture comprising 7-[4 (dimethylamino)phenyl]-7-(diphenylamino)furo[3,4-b]pyridine-5(7H)-one and 5.-[4- (dimethylamino)phenyl]-5-(diphenylamino)furo[3,4-b]pyridine-7 (5H)-one as a very light orange solid, m.p. 175-1 790 C. A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

EXAMPLE 10 Following a procedure similar to that described in Example 9 but employing 2.7 g of an isomer mixture comprising 2-[4-(dimethylamino)benzoyl]-3-pyridinecarboxylic acid and 3-[4 (dimethylamino)benzoyl]-2-pyridinecarboxylic acid, 4.0 g. of 4,4'-dioctyldiphenylamine and 25 ml. of acetic anhydride there was obtained 2.7 g. of an isomer mixture comprising 7-[4 (dimethylamino)phenyl]-7-[bis(4-octylphenyl)furo[3,4-b]pyridine-5(7H)-one and 5-[4 (dimethyla mino)phenyl]-5-[bis(4-octylphenyl) amino]f uro[3,4-b]pyridine-7( SH)-one as a light peach solid, m.p. 203-208 C. A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

EXAMPLE 11 Following a procedure similar to that described in Example 3 but employing 1.6 g. of an isomer mixture comprising 3-[4-(diethylamino)-2-methylbenzoyl]-4-pyridinecarboxylic acid and 4-[4 (diethylamino)-2-methylbenzoyl]-3-pyridinecarboxylic acid, 1.3 g. of 4,4' bis(dimethylamino)diphenylamine and 6 ml. of acetic anhydride there was obtained 1.5 g. of 3-[4 (diethylamino)-2-methylphenyl]-3 l bis[4-di methyla mino)phenyl]a minofuro[3,4 c]pyridine- 1 (3H)-one and 1 -[4-(dimethylamino)-2-methylphenyl]- 1 - bis[4-(dimethylamino)phenyljaminojfuro[3,4-cj- pyridine-3 (1 H)-one as a semi-solid. A toluene solution of the product contacted with acidic clay or phenolic resin developed a black image.

EXAMPLE 12 Following a procedure similar to that described in Example 3 but employing 1.6 g. of an isomer mixture comprising 3-[4-(diethylamino)-2-methylbenzoyl]-4-pyridinecarboxylic acid and 4-L4- (diethylamino)-2-methylbenzoyl]-3-pyridinecarboxylic acid, 0.9 g. of diphenylamine and 6 ml. of acetic anhydride there was obtained an isomer mixture comprising 3-[4-(diethylamino)-2-methylphenyl]-3 (diphenylamino)furo[3,4-c]pyridine-1 (3H)-one and 1 -[4-(diethylamino)-2-methylphenyl]- 1 - (diphenylamino)furo[3,4-c]pyridine-3(1 H)-one. A tolunene solution of the product contacted with acidic clay or phenolic resin developed a red-grape image.

EXAMPLE 13 Following a procedure similar to that described in Example 3 but employing 1.55 g. of an isomer mixture comprising 3-[4-(diethylamino)benzoyl]-4-pyridinecarboxylic acid and 4-[4 (diethylamino)benzoyl]-3-pyridinecarboxylic acid, 1.3 g. of 4,4'-bis-(dimethylarilino)diphenyla mine, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 1.5 g. of an isomer mixture comprising 3-[4-(diethylamino) phenyl]-3 {bis-[4-(dimethylamino) phenyl] amino] furo [3,4-c] pyridine-1(3H)-one and 1-[4-(dimethylamino) phenyl]-1 (bis [4-(dimethylamino) phenyl] amino] furo [3,4-c] pyridine-3(1H)one as a viscous oil. A tooluene solution of the product contacted with acidic clay or phenolic resin developed a brown image.

EXAMPLE 14 Following a procedure similar to that described in Example 3 but employing 1.55 g. of an isomer mixture comprisig 3-[4-(diethylamino)benzoyl]-4-pyridinecarboxylic acid and 4-[4 (diethylamino)benzoyl]-3-pyridinecarboxylic acid, 1.2 g. of 4-acetamido-N-phenylaniline, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 1.5 g. of an isomer mixture comprising 3-[4 (diethylamino) phenyl]-3- [(4-acetamidophenyl) phenylamino] furo [3,4-c] pyridine-1(3H)-one and 1-[4 (diethylamino) phenyl]-1--[(4-acetamidophenyl)-phenylamino [furo [3,4-c] pyridine-3 (1H)-one as a redbrown solid, m.p. 102-116 C. A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange-red image.

EXAMPLE 15 3.0 Grams of an isomer mixture comprising 3-[4-(diethylam ino) benzoyl]-4-pyridinecarboxylic acid and 4-[4-(diethylamino)benzoyl]-3-pyridinecarboxylic acid in 30 ml. of acetic anhydride was heated to 400C. After a solution formed, 4.0 g. of 4,4'-dioctyldiphenylamine was added, the mixture was stirred 7 hours, and then allowed to stand another 40 hours. The resulting solution was poured into 100 ml. of ice-water containing 76 ml. of concentrated ammonium hydroxide. The product was extracted into 75 ml. of toluene which was separated, dried over anhydrous calcium chloride and evaporated leaving an oil.Crystallization from hexane yielded 2.8 g. of an isomer mixture comprising 3-[4 (diethyla mino)phenyl]-3-[bis(4-octylphenyl)a mino]fu ro-[3,4-c]pyridine-1 (3H)-one and 1 -[4 (diethylamino) phenyl]-1-[bis (4-octyl phenyl) amino] furo [3,4-c] pyridine-3(1H)-one as a tan solid, m.p.

114-11 70C. A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

EXAMPLE 16 Following a procedure similar to that described in Example 3 but employing 3.0 g. of an isomer mixture comprising 3-[4-(diethylamino)benzoylj-4-pyridinecarboxylic acid and 4-[4 (diethylamino) benzoyl]-3-pyridinecarboxylic acid, 1.7 g. of diphenylamine and 30 ml. of acetic anhydride there was obtained 1.4 g. of an isomer mixture comprising 3-[4-(diethylamino)phenyl]-3 (diphenylamino)fu ro[3,4-c]pyridine- 1 (3H)-one and 1 -[4-(diethylamino)phenyl]- 1 (diphenylamino)furo[3,4-c]pyridine-3( 1 H)-one as a light orange solid, m.p. 135-141 OC. A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

EXAMPLE 17 2.6 Grams of an isomer mixture comprising 3-[4-(diethylamino)-2-methylbenzoyl]-4pyridinecarboxylic acid and 4-[4-(diethylamino)-2-methylbenzoyl]-3-pyridinecarboxylic acid in 30 ml. of acetic anhydride was heated to 400C and then 4.0 g. of 4,4'-dioctyldiphenylamine was added. The mixture was stirred for 3 hours at room temperature then poured into 100 ml. of ice-water and 76 ml. of concentrated ammonium hydroxide to yield 5.7 g. of an isomer mixture comprising 3-[4-(diethylamino)2-methylphenyl]-3-[bis (4-octylphenylamino) furo [3,4-c] pyridine-1 (3H)-one and 1 -[4-(diethylamino)-2methylphenyl]-1-[bis (4-octylphenyl) amino] furo [3,4-clpyridine-3 (1H)-one as a red solid, m.p.

58-1 OS0 C. A toluene solution of the product contacted with acidic clay or phenolic resin developed a violet image.

EXAMPLE 18 Following a procedure similar to that described in Example 3 but employing 1.63 g. of 3-[4 (diethylamino)-2-methylbenzoyl]-2-pyrazinecarboxylic acid, 1.3 g. of 4-[4'-bis-(dimethylamino)diphenylamine, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 0.9 g. of 7-[4 (diethylamino)-2-methylphenyl]-7 [bis [4-(dimethylamino) phenyl]-aminol furo [3,4-c] pyrazine-5 (7H)-one as a light orange solid, m.p. 193.5-195 C. (dec.). A toluene solution of the product contacted with acidic clay or phenolic resin developed a black image.

EXAMPLE 19 Following a procedure similar to that described in Example 3 but employing 1.6 g. of 3-[4 (diethylamino)-2-methyibenzoyl]-2-pyrazinecarboxylic acid, 0.9 g. of diphenylamine, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 0.1 g. of 7-[4-(diethylamino)-2-methylphenyl]-7 (diphenylamino)furo[3,4-c]pyrazine-5(7H) m.p. 189.5-191 OC. (dec.). A toluene solution of the product contacted with acidic clay or phenolic resin developed a red-grape image.

EXAMPLE 20 Following a procedure similar to that described in Example 3 but empioying 0.43 g. of 3-[4 (diethylamino)-benzoyl]-2-pyrazinecarboxylic acid, 0.34 g. of 4,4'-bis-(dimethylamino)diphenylamine, 0.5 mi. of pyridine and 6 ml. of acetic anhydride there was obtained 0.59 g. of 7-[4 (diethylamino)phenyl]-7jbis-[4-(dimethylamino)phenyl]aminoifurn[3,4-bjpyrazine-S(7H)-one, m.p.

61-740C. A toluene solution of the product contacted with acidic clay or phenolic resin developed a red-brown image.

EXAMPLE 21 Following a procedure similar to that described in Example 3 but employing 0.5 g. of 3-[4 (diethylamino)benzoyl]-2-pyrazinecarboxylic acid, 0.38 g. of 4-isopropoxy-N-phenylaniline, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 0.6 g. of 7-[4-(diethylamino)phenyl]-7-[(4- isopropoxyphenyl)phenylaminolfuro[3tSb]pyrazine-5(7H)-onet m.p. 75-82 C. A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange-brown image.

EXAMPLE 22 A mixture containing 0.7 g. of 3-L4-(dimethylamino)benzoyl-2-pyrazinecarboxylic acid, 1.0 g. of 4,4'-dioctyldiphenylamine and ml:of acetic anhydride was stirred and gently heated in a warm water bath for one hour. The product, 7-[4-(dimethylamino) phenyl]-7-[bis (4-octylphenyl) amino] furo [3,4- b]pyrazine-5(7H)-one was isolated by column chromatography as a rust-colored solid, m.p.

1 58-1 680C. A toluene solution of the product contacted with acidic clay or phenolic resin developed a reddish-brown image.

EXAMPLE 23 A mixture of 0.1 g. of 3-[4-(diethylamino)benzoyl]-2-pyrazinecarboxylic acid, 0.1 g. of diphenylamine and 2 ml. of acetic anhydride was wermed for several hours and then amowed to stand for three days. The product. 7-[4-(diethylamino) phenyl]-7-(diphenylamino) furo [3,4-b] pyrazine-5 (7H)-one was isolated by column chromatography as a light orange solid, m.p. 140-142.6 C. A toluene solution of this product contacted with acidic clay or phenolic resin developed a red image.

EXAMPLE 24 A mixture containing 0.15 g. of 3-[4-(diethylamino)benzoyl]-2-pyrazinecarboxylic acid, 0.18 g. of 4,4'-dioctyldiphenylamine and 3 ml. of acetic anhydride was gently heated for 5 hours and then allowed to stand ovemight. The product 7-[4-(diethylamino) phenyl]-7-[bis (4-octylphenylamino) furo [3,4b]pyrazine-5(7H)-one was isolated by column chromatography followed by crystallization from hexane to give a peach solid, m.p. 180-181 OC. A toluene solution of this product contacted with acidic clay orphenolic resin developed a red image.

EXAMPLE 25 A mixture containing 3.1 g. of 3-[4-(diethylamino)-2-methylbenzoyl]-2-pyrazinecarboxylic acid, 3.1 g. of 4,4'-dioctyidiphenylamine and 25 ml. of acetic anhydride was stirred in a warm water bath for 3 hours. The reaction mixture was poured into water and the resulting solid was collected and recrystallized from hexane to give 7-[4-(diethylamino)-2-methylphenyl]-7-[bis(4- octylphenyl)amino]furo[3,4-bipyrazine-5(7H)-one as a light tan solid, m.p. 180-1 870C. A toluene solution of this product contacted with acidic clay or phenolic resin developed a violet image.

EXAMPLE 26 Following a procedure similar to that described in Example 3 but employing 4.5 g. of an isomer mixture comprising 2-[( 1 -ethyl-2-methyl-3-indolyl)carbonyl]-3-pyridinecarboxylic acid and 3-[( 1-ethyl- 2-methyl-3-indolyl)carbonyl]-2-pyridinecarboxylic acid, 3.6 g. of 4-ethoxy-N-phenylaniline, 1 ml. of pyridine and 8 ml. of acetic anhydride there was obtained 5.5 g. of 7-(1 -ethyl-2-methyl-3-indolyl)-7-[(4ethoxyphenyl) phenylamino] furo [3,4-b] pyridine-5(7H)-one as a ten solid, m.p. 122-129 C. (dec.). A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

EXAMPLE 27 Following a procedure similar to that described in Example 3 but employing 1.6 g. of an isomer mixture comprising 2-[( 1 -ethyl-2-methyl-3-indolyl)carbonyl]-3-pyridine-carboxylic acid and 3-[( 1-ethyl- 2-methyl-3-indolyl)carbonyl]-2-pyridinecarboxylic acid, 2.0 g. of 4,4'-dioctyldiphenylamine, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 0.9 g. of 7-(1 -ethyl-2-methyl-3-indolyl)-7- [bis (4-octylhenyl) amino] furo [3,4-b] pyridine-5(7H)-one as a light tan solid, m.p. 1 870C. (dec.). A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

EXAMPLE 28 Following a procedure similar to that described in Example 3 but employing 1.6 g. of an isomer mixture comprising 2-[(1-ethyl-2-methyl-3-indolyl) carbonyl]-3-pyridinecarboxylic acid, and 3-[1-ethyl2-methyl-3-indolyl)carbonyl] -2-pyridinecarboxylic acid, 1.1 g. of 4-(dimethvlamino)-N-phenylaniline, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 1.3 g. of 7-(1 -ethyl-2-methyl-3indolyl)-7 [(4-dimethylamino) phenyl] phenylamino] furo [3,4-b]-pyridine-5(7H)-one as a gray solid, m.p.

191-1 920C. (dec.). A chloroform solution of the product contacted with acidic clay or phenolic resin developed a brown image.

EXAMPLE 29 Following a procedure similar to that described in Example 3 but employing 1.6 g. of an isomer mixture comprising 2-[(1-ethyl-2-methyl-3-indolyl) carbonyl]-3-pyridinecarboxylic acid and 3-[( 1-ethyl- 2-methyl-3-indolyl)carbonyl]-2-pyridinecarboxylic acid, 1.3 g. of 4,4'-bis-(dimethylamino)- diphenylamine, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 0.35 g. of 7-(1-ethyl-2-methyl-3-indolyl)-7-[bis [4-dimethylamino) phenyl] amino] furo [3,4-b] pyridine-5 (7H)-one as a white solid, m.p 205w206oC. (dec.). A chloroform solution of the product contacted with acidic clay or phenolic resin developed a brown image.

EXAMPLE 30 Following a procedure similar to that described in Example 3 but employing 1.6 g. of an isomer mixture comprising 2-[( 1 -ethyl-2-methyl-3-indolyl)ca rbonyl]-3-pyridinecarboxylic acid and 3-[( 1-ethyl- 2-methyl-3-indolyl)carbonyl]-2-pyridinecarboxylic acid, 0.95 g. of N-phenyl-m-toluidine, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 7-(1 -ethyl-2-methyl-3-indolyl)-7-(mtolylphenylamino) furo [3,4-b] pyridine-5(7H)-one as a yellow solid, m.p. 178-190 C. (dec.). A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

EXAMPLE 31 A mixture containing 4.5 g. of an isomer mixture comprising 2-[(1 -ethyl-2-methyl-3indolyl)carbonyl]-3-pyridinecarboxylic acid and 3-[( 1 -ethyl-2-methyl-3-indolyl)carbonyl]-2pyridinecarboxylic acid, 2.5 g. of diphenylamine and 30 ml. of acetic anhydride was stirred 6.5 hours, then treated with one ml. of pyridine and allowed to stand overnight. The reaction mixture was poured into 750 ml. of water and the resulting solid product was purified by column chromatography affording 7-(1 -ethyl-2-methyl-3-indolyl)-7-(diphenylamino)furo[3,4-b]pyridine-5(7H)-one as a light orange solid, m.p. 132.5-1 360C. A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

EXAMPLE 32 Following a procedure similar to that described in Example 3 but employing 1.6 g. of an isomer mixture comprising 3-[( 1 -ethyl-2-methyl-3-indolyl) carbonyl]-4-pyridinecarboxylic acid and 4-[( 1 -ethyl2-methyl-3-indolyl)carbonyl]-3-pyridinecarboxylic acid, 0.9 g. of diphenylamine, 0.5 ml. of pyridine and 6 ml. of acetic anhydride there was obtained 1-(1-ethyl-2-methyl-3-indolyl)-1-(diphenylamino) furo [3,4- c]pyridine-3(1 H)-one as a viscous oil. A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

EXAMPLE 33 Following a procedure similar to that described in Example 3 but employing 3.1 g. of 3-[(1 -ethyl 2-methyl-3-indolyl)carbonyl]-2-pyrazinecarboxylic acid, 2.2 g. of 4-ethoxy-N-phenylaniline, 2 ml. of pyridine and 10 ml. of acetic anhydride there was obtained 1.1 g. of 7-(1 -ethyl-2-methyl-3-indolyl)-7 [4-(ethoxyphenyl) phenylamino)] furo [3,4-b] pyrazine-5 (7H)-one as a light brown solid, m.p.

120-1 350C. (dec.). A toluene solution of the product contacted with acidic clay or phenolic resin developed a reddish-orange image.

EXAMPLE 34 Following a procedure similar to that described in Example 3 but employing 0.8 g. of 3-[(1-ethyl2-methyl-3-indolyl)carbonyl]-2-pyrazinecarboxylic acid, 1.0 g. of 4,4'-dioctyldiphenylamine, 0.25 ml. of pyridine and 3 ml. of acetic anhydride there was obtained 7-(1-ethyl-2-methyl-3-indolyl)-7-[bis(4- octylphenyl)amino]furo[3,4-b]pyrazine-5(7H)-one as a semi solid. A toluene solution of the product contacted with acidic clay or phenolic resin developed an orange image.

EXAMPLE 35 A mixture containing 4 g. of 3-[( 1 -ethyl-2-methyl-3-indolyl)carbo nyl]-2-pyrazinecarboxylic acid, 1.7 g. of diphenylamine and 1 5 ml. of acetic anhydride was stirred 1 hour at room temperature and then 30 minutes with gentle warming. The product, 7-(1 -ethyl-2-methyl-3-indolyl)-7 (diphenylamino)furo[3,4-b]pyrazine-5(7H)-one was isolated by column chromatography as a red solid, m.p. 98--1 000 C. A toluene solution of this product contacted with acidic clay or phenolic resin developed an orange image.

It is contemplated that by following procedures similar to those described in the foregoing examples but employing the appropriate Z-CO-pyridinecarboxylic acids of Formula II and appropriately substituted diaryiamines of Formula Ill there will be obtained the compounds of Formula I, Examples 36-65, presented in the following Table.

Ex. A R3 R4 R5 R6 R7 Y1 Y2 Y3 Y4 36 # C2H5O C2H5 C2H5 - - H 4-C5H17 H 4-C5H17 37 " (CH3)2N CH2 CH2 - - H 4-C5H17 H 4-arylakkyl* 38 " H C2H5 C5H5CH2 - - H H H 3-CH3 39 " Cl C2H5 C2H5 - - H H H 4-NHSO2C6H4CH3-p 40 " - - - H CH3 H H H H m.p. 172-191 C. 41 " - - - H C6H5 H H4-C5H17 H 4-arylalkyl* m.p. 128-135 C. 42 " - - - CH5 CH3 H H H 3-Cl m.p. 184-185 C. 43 " - - - n-C3H9 CH3 H H H 4-NHSO2C6H4CH3-P m.p. 105 C. 44 " - - - n-C5H17 CH3 H H H H m.p. 163.7-165 C.

* Derived from octylated arylalkylated diphenylamine sold by the B.F. Goodrich Chemical Co. under the tradename Good-rite Antioxidant 3190.

Ex. 1 A R2 R4 R5 R6 R7 Y1 Y2 Y3 Y4 45 # C2H5O C2H5 C2H5 - - H 4-C8H17 H 4-C8H17 46 " (CH3)2N CH3 CH3 - - H 4-C6H17 H 4-arylalkyl* 47 " H C2H5 C5H5CH2 - - H H H 3-CH3 48 " Cl C2H5 C2H5 - - H H H 4-NHSO2C6H4CH3-p 49 " - - - H CH3 H H H H 50 " - - - H C6H5 H 4-C8H17 H 4-artylalkyl* 51 " - - - CH3 CH3 H H H 3-Cl 52 " - - - n-C4H9 CH3 H H H 4-NHSO2C6H6 53 " - - - n-C8H17 CH3 H H H H 54 # - - - H CH3 H H H H 55 " n-C4H9 CH3 CH3 - - H H H 4-Br 56 " (CH3)2CHCH2O CH3 CH3 - - 2-Cl 4-Cl 2-Cl 4-Cl 57 # (sec-C4H9)2N sec-C4H9 sec-C4H5 - - H H H H 58 " Br CH2 CH2 - - H 3-C4H2O H 3-C4H2O 59 " - - - n-C18H37 CH3 3-C2H5 5-C2H19 3-C2H5 5-C9H19

Ex. A R3 R4 R5 R6 R7 Y1 Y2 Y3 Y4 60 # Br CH3 CH2 (CH2)2CH(CH2)6 H H H 3-(CH3)3C 61 " - - - n-C6H13 CH3 H H 4-n-C6H13 H 62 " - - - C2H5 CH3 H H H 4-NHCOC4H3 63 " - - - C2H5 CH3 H H H 4-NH2 64 " H CH3 CH3 - - H H H 4-CHCH2C6H5 CH3 65 " C2H5 C2H6 C2H5 - - H 2-Cl H 4-F EXAMPLE 66 A solution containing 1.46 g. of the color former of Example 28 in 60 ml. of isopropylbiphenyl and a solution containing 5 g. of carboxymethylcellulose in 200 mi. of water were mixed and emulsified by rapid stirring. The desired particle size (5 microns) was checked by microscope. To the emulsion was added a solution containing 1 5 g. of pigskin gelatin in 120 ml. of water. The pH was adjusted to 6.5 with 10% aqueous sodium hydroxide with rapid stirring, and following the gradual addition of 670 ml. of water at 500 C. the pH was adjusted to 4.5 with 10% aqueous acetic acid with continued rapid stirring.

After 5 minutes the mixture was cooled to 1 50C., treated with 10 g. of 25% aqueous glutaraldehyde and rapidly stirred for 1 5 minutes. The resulting microcapsule dispersion was stirred more slowly overnight, diluted with waterto 1120 g. and coated on white typewriter paper sheets (0.001 5 in. film thickness). The sheets were air dried. Duplicate typewritten images were made on receiving sheets coated with either phenolic resin or acidic clay. The color former of Example 28 produced a brown image on both types of receiving sheets.

EXAMPLE 67 A polyvinyl alcohol dispersion of the color former of Example 28 was prepared by shaking 1 hour on a paint shaker a mixture containing 2.0 g. of the color former, 3.7 g. of water, 8.6 g.of 10% aqueous polyvinyl alcohol and 10 g. of zirconium grinding beads. A polyvinyl alcohol dispersion of bisphenol A was prepared by shaking a mixture containing 9.8 g. of bisphenol A, 18.2 g. of water, 42 g. of 10% aqueous polyvinyl alcohol and 70 ml. of zirconium grinding beads. The coating mixture was made by combining and thoroughly mixing 2.1 g. of the polyvinyl alcohol dispersion of the color former with 47.9 g. of the polyvinyl alcohol dispersion of bisphenol A. The coating mixture was applied (at thicknesses of 0.003 and 0.001 5 inches) to white mimeo paper sheets and the sheets were dried at room temperature. Contacting the coated sheets with a heated stylus at a temperature between 11000. and 1 5000. produced a purple image.

Claims (26)

1. A compound having the Formula I (herein) wherein A is a divalent radical of the Formula (a), (b), (c), (d) or (e) herein Y1, Y2, Y3 and Y4 are the same or different hydrogen, halo, lower-alkoxy, alkyl having from 1 to 9 carbon atoms, phenyl-lower-alkyl or NR,R2 where R1 is hydrogen or lower alkyl and R2 is hydrogen, lower-alkyl, lower alkanoyl, phenylsulfonyl or lower alkyl-substituted phenylsulfonyl; Z is a monovalent radical of the Formula (f) or (g) herein in which R3 is hydrogen, lower alkyl, lower alkoxy, halo or di-lower-alkylamino; R4 is lower alkyl; R5 is lower alkyl or benzyl; Re is hydrogen or non-tertiary alkyl having from 1 to 18 carbon atoms; and R7 is hydrogen, phenyl or non-tertiary lower alkyl.

2. A compound according to claim 1, wherein A is (a) or (d).

3. A compound according to claim 2, wherein Z is (f), R3 is hydrogen or iower-alkyl and R4 and R5 are each lower alkyl.

4. A compound according to claim 2, wherein Z is (g) and, Y, and Y3 are each hydrogen.

5. A compound according to claim 3, wherein Y and Y3 are each hydrogen.

6. A compound according to claim 5, wherein Y2 and Y4 are the same or different hydrogen or alkyl having from 1 to 9 carbon atoms.

7. 7-[4-(Dimethylamino)phenyl]-7-(diphenylamino)furo[3,4-b]pyridine-5-(7H)-one.

8. 5-[4-(Dimethylamino)phenyl]-5-(diphenylamino)furo[3,4-b]pyridine-7(5H)-one.

9. 7-[4-(Dimethyla mino)phenyl]-7-[bis-(4-octylphenyl)amino]furo[3 ,4-b]pyridine-5-(7 H)-one.

10. 5-[4-(Dimethylamino)phenyl]-5-[bis-4-octylphenyl)aminojfuro[3,4-bjpyridine-7(5H)-one.

11. 7-[4-Diethylamino)-2-methylphe nyl]-7-[bis(4-octylphenyl)a mi no]furo[3,4-b]pyridine-5-[(7H)one.

12. 5-[4-(Di methylamino)-2-methylphenyl]-5-[bis(4-octyl-phenyl)ami no]furo[3,4-b] pyridine7(5H)-one.

13. 7-(1 -Ethy!-2-methyi-3-indolyl)-7-(diphenylamino)-furoL3,4-bipyridine-5-(7H)-one.

14. 5-[( 1 -Ethyl-2-methyl-3-indolyl)-5-(diphenylamino)furo[3,4-b]pyridine-7(5H)-one.

1 5. 7-(1 -Ethyl-2-methyl-3-indolyl)-7-[bis(4-octylphenyl)aminojfuro[3,4-b]pyridine-5-(7 H)-one.

1 6. 5-( 1 -Ethyl-2-methyl-3-indolyl)-5-[bis(4-octylphenyl)amino]furo[3,4-b]pyridine-7(5H)-one.

17. A process for producing a compound according to claim 1, which comprises reacting a carboxylic acid having the Formula II (herein) with a diarylamine having the Formula III (herein) in the presence of the anhydride of an alkanoic acid having from 2 to 5 carbon atoms.

18. A process according to claim 1 7, wherein said anhydride of an alkanoic acid having from 2 to 5 carbon atoms is acetic anhydride.

1 9. A process for producing a compound according to claim 1, which comprises reacting a carboxylic acid having the Formula II (herein) with thionyl chloride, phosphorous oxychloride, phosphorus trichloride or phosphorous pentachloride; and reacting the resulting product with a diarylamine having the Formula Ill (herein) in the presence of an organic base.

20. A process according to claim 19, wherein said inorganic acid chloride is thionyl chloride and said organic base is selected from the group consisting of said diarylamine, pyridine and urea.

21. A pressure-sensitive carbonless duplicating system or thermal marking system containing a color-forming substance comprising a compound according to any one of claim 1 to 1 6.

22. A pressure-sensitive carbonless duplicating system according to claim 21, comprising a support sheet coated on one side with a layer of pressure-rupturable microcapsules containing a liquid solution of the color-forming substance.

23. A thermal marking system according to claim 21, comprising a support sheet coated on one side with a layer containing a mixture of the color-forming substance and an acidic developer arranged such that application of heat will produce a mark-forming reaction between the color-forming substance and the acidic developer.

24. A compound according to claim 1, or a pressure-sensitive carbonless duplicating system or thermal marking system comprising same substantially as herein described with reference to the Examples.

25. A process for preparing a compound according to claim 1, substantially as herein described with reference to the Examples.

26. A compound when prepared by the process according to any one of claims 1 7-19 and 25.