GB804089A - Process for the preparation of cyclohexanone derivatives - Google Patents

Abstract

The invention comprises compounds of the general formula <FORM:0804089/IV (b)/1> wherein R2 and R3 are hydrogen atoms, lower alkyl radicals containing at most four carbon atoms or aryl radicals and a process for the preparation of compounds of the general formula <FORM:0804089/IV (b)/2> wherein R represents a hydrogen atom or a lower alkyl radical as defined above and R1, R2 and R3 represent hydrogen atoms, lower alkyl radicals as defined above or aryl radicals which comprises reacting an enolic ether of the general formula <FORM:0804089/IV (b)/3> in which R1 represents a lower aliphatic hydrocarbon radical containing from 3 to 5 carbon atoms and R has the significance set forth, with an alk-1-enyl-magnesium halide of the general formula <FORM:0804089/IV (b)/4> wherein X represents a chlorine or bromine atom and the radicals R1, R2 and R3 have the significances set forth and decomposing the magnesium derivative formed by treatment with a dilute mineral acid. In examples: 2-methyl - 3 - vinylcyclohex - 2 - ene - 1 - one is obtained by treating 2-methyl-3-isobutoxy-cyclohex - 2 - ene - 1 one with vinyl magnesium bromide, prepared by reacting magnesium with vinyl bromide in tetrahydrofuran and adding excess dilute sulphuric acid to the reaction product (I); 3-vinyl-cyclohex-2-ene-1-one is obtained by reacting vinyl magnesium bromide and 3-isobutoxy-cyclohex-2-ene-1-one in a similar process (II). Other compounds made by analogous processes are 3-(1-propenyl) cyclohex-2-ene-1-one, 3-(1-isocrotyl) cyclohex - 2 - ene - 1 - one and 3 - (1 - a - methyl-styryl)-cyclohex-2-ene-1-one.