Allyldimethyltritylsilane: construction of enantiomerically pure cyclobutano[c]fused pyrrolidines

Cyclobutannulation of the bicyclic lactam with allyldimethyltritylsilane is accomplished in high yield with good diastereoselectivity. The resulting tricyclic system is converted to a enantiomerically pure cyclobutane-fused pyrrolidine.