Prins Reaction

"This thesis is divided into 5 chapters. The first chapter reviews the literature of Carbonyl-ene and Prins reactions. Recent advances in these areas and their application to natural product synthesis and other targeted syntheses are discussed.
The second chapter discusses the concept of desymmetrisation using selected examples, including desymmetrising Carbonyl-ene reactions.
Chapter Three introduces and discusses the work undertaken in studying the desymmetrising intramolecular carbonyl-ene of a meso-dialdehyde.
Chapter Four details the concept of pyruvate-Prins cyclisation giving examples of its potential use. The chapter also gives examples of the use of rigid stereodefined scaffolds and their application. The chapter describes the reactivity of substituted pyruvate esters with cyclic enol ethers, and the elaboration of the cyclised products.
The fifth chapter provides experimental details of the procedures reported."

En esta contribución se hace una revisión de los métodos para la síntesis del nopol. Los procesos convencionales abarcan la síntesis térmica y la catalítica con ZnCl2 y los emergentes corresponden a los catalíticos heterogéneos. Se destaca el uso de catalizadores de Sn soportado en materiales mesoporosos producto de las investigaciones de la última década en el Grupo Catálisis Ambiental. La evaluación de las tecnologías existentes de producción de nopol muestra ventajas de la síntesis térmica y la catálisis heterogénea frenteal uso de ZnCl2, especialmente por los costos potenciales en la separación y tratamiento de las sales inorgánicas. No obstante, cualquier intento de obtener una alternativa comercial de la tecnología reciente debería reducir los costos requeridos en la producción y regeneración del material catalítico y minimizar el requerimiento de solvente, con el fin que las condiciones moderadas de reacción de la catálisis heterogénea compense adecuadamente los requerimiento...

The first total syntheses of the Lycopodium alkaloids (+)-nankakurine A (2), (+)-nankakurine B (3), and the originally purported structure 1 of nankakurine A were accomplished. The syntheses of 2 and 3 feature a demanding intramolecular azomethine imine cycloaddition as the key step for generating the octahydro-3,5-ethanoquinoline moiety and installing the correct relative configuration at the spiropiperidine ring juncture. The cyclization precursor was prepared from octahydronaphthalene ketone 50, which was assembled from enone (+)-9 and diene 48 by a cationic Diels-Alder reaction. The Diels-Alder reactants were synthesized from 5-hexyn-1-ol (16) and (+)-pulegone (49), respectively. The tetracyclic ring system of 1 was generated using an unprecedented nitrogen-terminated aza-Prins cyclization cascade. The enantioselective total syntheses of (+)-nankakurine A (2) and (+)-nankakurine B (3) establish the relative and absolute configuration of these alkaloids and are sufficiently conci...

The first total syntheses of the Lycopodium alkaloids (+)-nankakurine A (2), (+)-nankakurine B (3), and the originally purported structure 1 of nankakurine A were accomplished. The syntheses of 2 and 3 feature a demanding intramolecular azomethine imine cycloaddition as the key step for generating the octahydro-3,5-ethanoquinoline moiety and installing the correct relative configuration at the spiropiperidine ring juncture. The cyclization precursor was prepared from octahydronaphthalene ketone 50, which was assembled from enone (+)-9 and diene 48 by a cationic Diels-Alder reaction. The Diels-Alder reactants were synthesized from 5-hexyn-1-ol (16) and (+)-pulegone (49), respectively. The tetracyclic ring system of 1 was generated using an unprecedented nitrogen-terminated aza-Prins cyclization cascade. The enantioselective total syntheses of (+)-nankakurine A (2) and (+)-nankakurine B (3) establish the relative and absolute configuration of these alkaloids and are sufficiently conci...