Aziridination of α,β-unsaturated esters bearing allylic hydroxy groups with 3-acetoxyaminoquinazolinones: evidence for a mechanism comprising Michael addition–SN2 nucleophilic displacement of acetoxy for aziridination of α,β-unsaturated esters

Abstract

Aziridinations of the allylic alcohol-bearing α,β-unsaturated esters 6 and 7 and their corresponding acetates 8 and 9 have been carried out under standard conditions using 3-acetoxyaminoquinazolinone 2. Whereas the preferred sense of diastereoselectivity in aziridination of allyl alcohol 6 is inverted by comparison with its acetate 8, the preferred sense of diastereoselectivity is retained in aziridination of allylic alcohol 7 by comparison with its acetate 9. A mechanism is proposed for aziridinations of α,β-unsaturated esters in which Michael addition of the N-acetoxy nitrogen to the β-position of the ester runs ahead of S_N2-type nucleophilic displacement of the acetoxy group from nitrogen.