Synthesis of Substituted Butenolides and Related Natural Products

Butenolides are ,beta-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 Gamma-substituted butenolide derivatives by utilizing the concept of vinylogy, which usually involves the carbon-carbon formation with an appropriate electrophile at the Gamma-position of butenolides, has triggered increasing interest. This thesis presents an efficient, simple, scalable and direct stereoselective vinylogous aldol reaction of beta-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 -halo-beta-substituted butenolides.

Autorentext

Dr. Karak graduated in Chemistry (Hons.) from the Vidyasagar University in 2009 and obtained a MSc at the Nagpur University in 2011. In 2017, he earned his PhD (Doctor Scientiae) in Agrochemistry with research area in Organic Chemistry from the Universidade Federal de Viçosa. Currently, he is a postdoctoral fellow at the Kyushu University, Japan.

Klappentext

Butenolides are , -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 -substituted butenolide derivatives by utilizing the concept of vinylogy, which usually involves the carbon carbon formation with an appropriate electrophile at the -position of butenolides, has triggered increasing interest. This thesis presents an efficient, simple, scalable and direct stereoselective vinylogous aldol reaction of -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 -halo- -substituted butenolides.