Stereogenic-at-metal Zn- and Al-based N-heterocyclic carbene (NHC) complexes as bifunctional catalysts in Cu-free enantioselective allylic alkylations.

ABSTRACT: Investigations detailed herein demonstrate the ability of chiral bidentate N-heterocyclic carbenes to promote directly-without the need for a Cu salt-site- and enantioselective C-C bond forming reactions. Within this context, catalytic allylic alkylations of various allylic phosphates with dialkylzinc and trialkylaluminum reagents, performed with chiral bidentate imidazolinium salts and in the absence of a Cu salt, are described. The Cu-free transformations deliver products bearing tertiary or (all-carbon) quaternary stereogenic centers with exceptional site- (>98:<2 S(N)2':S(N)2) and high enantioselectivity [up to 97.5:2.5 enantiomer ratio (er)]. A chiral Zn-based N-heterocyclic carbene (NHC) complex, which serves as the catalyst for the enantioselective allylic alkylation reactions, is i

SUBMITTER: Lee Y 

PROVIDER: S-EPMC2761703 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature