Absolute Configuration of 2-(tributylstannyl)-pyrrolidine by Anomalous Dispersion X-ray Analysis

Enantiopure 2-(tributylstannyl)pyrrolidine hydroiodide may be prepared in excellent yield by TMSI treatment of the corresponding N-Boc compound, which is in turn prepared by asymmetric deprotonation (s-BuLi‚sparteine) and stan- nylation, as described in the literature. Crystals of the hydroiodide salt suitable for X-ray analysis were obtained, and although there is some disorder about the butyl groups, analysis using anomalous dispersion establishes the absolute configuration as S.