Diastereoselective cycloadditions involving methyleneaziridines: Reactions with tetracyanoethylene

2-Methyleneaziridines 2a-e containing a stereogenic centre on the N-substitutent undergo [2 pi+2 pi] cycloadditions with tetracyanoethylene to produce diastereomeric 5-azaspiro[3.2]hexanes 3a-e and 4a-e in moderate to good yields (32-82%). The diastereoselectivity of these cycloadditions (12-68% de) is shown to be dependent on the nature of the N-substitutent; The structure of 5-azaspiro[3.2]hexane 4a has been unambiguously determined by X-ray crystallography. (C) 1999 Elsevier Science Ltd. All rights reserved.