Acetal-initiated Prins bicyclization for the synthesis of hexahydrofuro-[3,4-c]furan lignans and octahydropyrano[3,4-c]pyran derivatives

Transition Metal/Lewis Acid Catalyzed Reactions of Zerumbone for Diverse Molecular Motifs

Zerumbone is a naturally occurring humulene type sesquiterpene, isolated from the rhizomes of Zingiber zerumbet (L.) Smith with excellent therapeutic potential and is recognized as a valuable synthon for the construction of diverse array of natural product motifs. In this review, we intended to highlight our achievements in utilizing abundant natural product zerumbone and its derivatives for the development of pharmacologically relevant molecular scaffolds. We provided an account of the transition-metal catalyzed 1,4-conjugate addition reactions of zerumbone and its derivatives along with palladium-catalyzed cross-couplings, transition metal-based Lewis acid promoted interrupted Nazarov cyclisation reaction with substituted indoles and transannular cyclizations, photo-induced transformations of zerumbone and its epoxide.

Substitution dependent stereoselective construction of bicyclic lactones and its application to the total synthesis of pyranopyran, tetraketide and polyrhacitide A

A novel strategy has been developed for the synthesis of bicyclic lactones and has been successfully applied to the total synthesis of pyranopyran, tetraketide, and polyrhacitide A.

A novel domino cyclization for the stereoselective synthesis of indeno[2,1-c]pyran and cyclopenta[c]pyran derivatives

A novel bicyclization of 2-(2-(hydroxymethyl)-1-methylene-2,3-dihydro-1H-inden-2-yl)ethanol with aldehydes in the presence of 10 mol% BF3·OEt2 in dichloromethane at 0-25 °C affords the biologically relevant indeno[2,1-c]pyran scaffolds in good yields with high selectivity. Similarly the bicyclization of 2-(1-(hydroxymethyl)-2-methylenecyclopentyl)ethanol with aldehydes generates the corresponding cyclopenta[c]pyran derivatives under similar conditions. This method is very useful to produce hematoxylin and brazilin like scaffolds.

Tandem Prins/Wagner/Ritter process for the stereoselective synthesis of (3-oxabicyclo[4.2.0]octanyl)amide and (1-(5-aryltetrahydrofuran-3-yl)cyclobutyl)amide derivatives

A novel synthesis of 4-aryl-(3-oxabicyclo[4.2.0]octan-1-yl)amide and (1-(5-aryltetrahydrofuran-3-yl)cyclobutyl)amide derivatives was achieved through a sequential Prins/Wagner/Ritter process.