Stereocontrolled enantioselective total synthesis of the [2+2] quadrigemine alkaloids.

ABSTRACT: A unified strategy for enantioselective total synthesis of all stereoisomers of the 2+2 family of quadrigemine alkaloids is reported. In this approach, two enantioselective intramolecular Heck reactions are carried out at the same time on precursors fashioned in four steps from either meso- or (+)-chimonanthine to form the two critical quaternary carbons of the peripheral cyclotryptamine rings of these products. Useful levels of catalyst control are realized in either desymmetrizing a meso precursor or controlling diastereoselectivity in elaborating C₂-symmetic intermediates. None of the synthetic quadrigemines are identical with alkaloids isolated previously and referred to as quadrigemines A and E. In addition, we report improvements in our previous total

SUBMITTER: Canham SM 

PROVIDER: S-EPMC4526107 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature