Stereocontrolled synthesis of 5-Acyl-3,4-dihydro-2H-pyrroles and related heterocycles via intramolecular 2-propylidene-1,3-bis(silane)-acylnitrilium ion cyclizations

摘要

2-Propylidene-1,3-bis(silane)s have been shown to be highly effective terminators in heteroannu- lations initiated by C-acylnitrilium ions. These cyclizations proceed under exceedingly mild reaction conditions with good to excellent levels of substrate-derived stereocontrol to provide the corre- sponding Δ-pyrrolines possessing a functionalizable allylsilane moiety. Sequential reduction/N- tosylation of these products leads to the stereoselective formation of cis-pyrrolidine derivatives.