Synthesis and reactions of acyclic alkynals and alkynones

Abstract

A general synthetic route was developed for the preparation of the acetylenic carbonyl compounds using an adipic acid monomethyl ester as a model system. Advantages of this procedure over Eschenmoser and Tanabe fragmentation method is general applicability that it can be applied to various ring size. The intramolecular photocycloaddition of the alkynals and the alkynones was tested but failed to obtain any photoadduct. It is shown that intramolecular cycloaddition of acetylenic nitrones could afford the desired isoxazolidine derivatives when the substrate molecular has appropriately modified. The availability of the alkynals (or alkynones) by the developed synthetic sequences could open the ways of testing various possibility of the reactions between carbonyl compounds(or compounds derived from carbounyl groups) and C-C triple bonds in intramolecular fashion.