Transition metal-catalyzed cyclization reactions and stereoselective synthesis of exocyclic alkenes

Yantao Zhang, Purdue University

Abstract

Alkenyl- and arylpalladium species generated from oxidative addition of the corresponding halide and palladium(0) catalyst were found to add to carbon-carbon double bonds in an intramolecular manner and undergo facile dehydropalladation reaction subsequently. Bicyclic and polycyclic fused-, spiro-, and bridged-ring compounds were synthesized in high yields via this intramolecular version of Heck reaction. Catalytic carbopalladation of alkynes was also developed as a versatile synthetic methodology. Tandem and cascade type reactions of polyenynes leading to polycyclic compounds were studied. Synthesis of a tetracyclic compound with the common steroid skeleton from a linear precursor was achieved in one single step using the method developed. A general carbonylative cyclization methodology consisting of oxidative addition, CO insertion, and intramolecular trapping of an acylpalladium intermediate by C-enolate was developed. Several approaches leading to the stereoselective synthesis of stereo-defined exocyclic alkenes were investigated, involving the use of $\alpha$-silylepoxide opening-elimination, cyclization of difunctional alkenes obtained from allylmetallation, cyclialkylation of alkenylmetals and palladium catalyzed cyclization respectively. In each case, stereoselectivity was observed to be $>$96%.

Degree

Ph.D.

Advisors

Negishi, Purdue University.

Subject Area

Organic chemistry

COinS