A facile conversion of beta-keto carbonyl compounds to alpha, beta-unsaturated-gamma-oxo carbonyl systems and a study of ketal-derived oxonium ylides

An efficient method for the conversion of versatile β-keto carbonyl compounds to the corresponding α,β-unsaturated-γ-oxo carbonyl structural units was developed. This methodology was applied to β-keto esters, amides and lactones. In most cases generation of the olefinic functionality proceeded with complete E-selectivity. The utility of this chemistry was demonstrated through a formal synthesis of R-(−)-pyrenophorin, an asymmetric total synthesis of (+)-patulolide A and a racemic synthesis of patulolide B. An extensive study of ketal-derived oxonium ylides and the subsequent rearrangement was also accomplished. The application of this chemistry was applied to Bu-2313 and a unique class of compounds known as the hyperolactones.