Aziridination of cyclic dienes with enantiopure 3-acetoxyaminoquinazolin-4(3H)-ones

Abstract

Aziridination of cyclopentadiene and cyclohepta-1,3-diene with (S)-3-acetoxyamino-2-(3-hydroxy-2,2-dimethylpropyl)quinazolin-4(3H)-one 6 (Q¹NHOAc) in the presence of titanium(IV) tert-butoxide in dichloromethane takes place highly diastereoselectively: X-ray structure determinations show that the preferred sense of diastereoselectivity in both cases is the same as that previously found for aziridination of butadiene with 6. Aziridination of cyclohexa-1,3-diene with 6 was less diastereoselective in dichloromethane solution but highly diastereoselective in acetonitrile: in this solvent two diastereoisomeric cis-4-(Q¹-amino)cyclohexen-3-ols 27 and 28 were also obtained as by-products. The same two amino alcohols were obtained by ring-opening of the aziridine with acid and were each converted into Q¹-free oxazolidinones having optical rotations which were similar in magnitude but opposite in sign.