Aziridination of 2- and 3-phenyl-substituted allylic alcohols with 3-acetoxyaminoquinazolinones: probing the nature of the transition state from the diastereoselectivity of aziridination

Aziridination of phenyl-substituted allylic alcohol 10 with 3-acetoxyaminoquinazolinone 3 (Q1NHOAc) and with 22 (Q2NHOAc) has been studied. The diastereoselectivity of these reactions is markedly changed by carrying them out in the presence of aqueous sodium hydrogen carbonate solution and under these conditions aziridinations of 10 and of its ester analogue 5 with Q2NHOAc give the same magnitude and sense of diastereoselectivity (with PhCO2Me). An explanation for these changes in diastereoselectivity is offered based upon differences in the nature of the hydrogen bonding in the transition states for aziridination of 10 with and without the presence of acetic acid.