Abstract
(matrix presented) Treatment of alkynyltungsten complexes with tethered aziridines in the presence of BF 3 ·Et 2 O led to [3 + 2]-cycloaddition reactions, affording bicyclic tungsten-enamine species stereoselectively. The stereochemistry of the resulting product reveals that ring opening of aziridine is initiated by S N 2 attack of the tungsten fragment. Decomplexation of these organometallics with I 2 in CH 2 C 2 , followed by hydrolysis, afforded only cis-fused bicyclic lactams efficiently.