Synthesis of Substituted Butenolides and Related Natural Products

Butenolides are αβ-unsaturated lactone and are found in many natural and unnatural products with diverse biological properties. Owing to the prevalence of the substituted butenolides much effort has been directed towards developing efficient methodologies for their synthesis and transformations. Among them stereoselective access of the γ-substituted butenolide derivatives by utilizing the concept of vinylogy which usually involves the carbon–carbon formation with an appropriate electrophile at the γ-position of butenolides has triggered increasing interest. This thesis presents an efficient simple scalable and direct stereoselective vinylogous aldol reaction of β-aminosubstituted butenolides (tetronamides) with aldehydes. In addition this thesis also describes the total syntheses of butenolide core bearing marine natural metabolites rubrolides by using a highly regioselective late-stage bromination strategy from appropriate intermediates and apprises a facile reductive dehalogenation of α-halo-β-substituted butenolides.