READILY AVAILABLE NITRENE PRECURSORS INCREASE THE SCOPE OF EVANS ASYMMETRIC AZIRIDINATION OF OLEFINS

The performance of the copper-catalyzed asymmetric aziridination of ol efins is highly dependent on the properties of the nitrene precursor. Our preliminary results show significant improvements of both enantios electivity and chemical yields when [N-(4-nitrobenzenesulfonyl)imino] phenyliodinane 1b (p-NO2C6H4SO2N=IPh) is employed instead of the commo nly used p-tolyl analog 1a (PhI=NTs). This paper reports the compariso n of some nitrene precursors for the copper-catalyzed asymmetric aziri dination of olefins, utilizing the olefin as the limiting component an d 1.5 equivalents of the nitrene precursor. The aziridine derivatives of several olefins were obtained in moderate to excellent yields and w ith enantioselectivity up to 95% ee. (C) 1997 Elsevier Science Ltd.