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

The indium-mediated allylation of alpha-aldimino and -ketimino esters 3 with allylic bromides proceeds with high diastereoselectivity to yield homoallylic alpha-amino ester derivatives 5, in both THE 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 C=N 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 alpha-methylidene-gamma-butyrolactams 6 with an alkoxycarbonyl group on the ring bearing the nitrogen atom. (C) 2016 Elsevier Ltd. All rights reserved.