Cat. on a hot tin roof: Enantioselective catalytic Michael addition of α-cyanoketones to acrylates under bifunctional organocatalysis was used to construct the unique arylic all-carbon quaternary stereocenter, which is synthetically crucial in the chemical synthesis of optically pure cis-aryl hydroindole alkaloids. The protocol offers an asymmetric route to (+)-vittatine, (+)-epi-vittatine, and (+)-buphanisine.
Biosynthesis-Inspired Intramolecular Oxa-Conjugate Cyclization of α,β-Unsaturated Thioesters: Stereoselective Synthesis of 2,6-<i>cis</i>-Substituted Tetrahydropyrans
作者:Haruhiko Fuwa、Kenkichi Noto、Makoto Sasaki
DOI:10.1021/ol200333p
日期:2011.4.1
Intramolecular oxa-conjugate cyclization of alpha,beta-unsaturated thioesters under Bronsted acid catalysis, inspired by biosynthesis of polyketide natural products, provides a variety of 2,6-cis-substituted tetrahydropyran derivatives with excellent diastereoselectivities. An added bonus of this methodology is that the product tetrahydropyrans could be readily elaborated to various derivatives by exploiting the unique reactivity of the thioester group.