Diastereoselection in the formation of spirocyclic oxindoles by the intramolecular Heck reaction.

ABSTRACT: Diastereoselective double Heck cyclizations of cyclohexene diamides 1 and 3 form contiguous quaternary stereocenters, with diastereoselection being controlled by the trans-diol protecting group. In this, the first in a series of two papers, the origin of diastereoselection in the first ring-closure step of these reactions is examined. Nine simplified analogues of 1 and 3 were synthesized and cyclized to discern what structural features are required to realize high diastereoselection in the first intramolecular Heck reaction. These studies show that high stereoselection (>20:1) does not arise from a single structural feature: it is seen only in substrates that contain both a trans-acetonide and a tertiary amide substituent at C2. Two subtle factors appear to be involved: (1) Avoidance of ec

SUBMITTER: Overman LE 

PROVIDER: S-EPMC2585599 | biostudies-literature | 2006 Mar

REPOSITORIES: biostudies-literature