Stereocontrolled Synthesis of 5-Acyl-3,4-dihydro-2H-pyrroles and Related Heterocycles via Intramolecular 2-Propylidene-1,3-bis(silane)−Acylnitrilium Ion Cyclizations

2-Propylidene-1,3-bis(silane)s have been shown to be highly effective terminators in heteroannulations 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 corresponding Δ 1 -pyrrolines possessing a functionalizable allylsilane moiety. Sequential reduction/ N -tosylation of these products leads to the stereoselective formation of cis- pyrrolidine derivatives.