Indium-mediated diastereoselective allylation of N-tert-butanesulfinyl imines derived from α-ketoesters

Abstract

The indium-mediated allylation of α-aldimino and -ketimino esters 3 with allylic bromides proceeds with high diastereoselectivity to yield homoallylic α-amino ester derivatives 5, in both THF and water as solvents. The reactions are diastereospecific, the stereochemical outcome depending on the configuration of both the sulfur atom of the sulfinyl group and the Cdouble bond; length as m-dashN double bond. Of particular interest are the reaction products using ethyl bromomethylacrylate as allylating reagent because amino diesters are obtained, which can be easily transformed into enantiomerically pure α-methylidene-γ-butyrolactams 6 with an alkoxycarbonyl group on the ring bearing the nitrogen atom.