Readily available nitrene precursors increase the scope of Evans' asymmetric aziridination of olefins
作者:Mikael J. Södergren、Diego A. Alonso、Pher G. Andersson
DOI:10.1016/s0957-4166(97)00496-5
日期:1997.11
The performance of the copper-catalyzed asymmetric aziridination of olefins is highly dependent on the properties of the nitrene precursor. Our preliminary results show significant improvements of both enantioselectivity and chemical yields when [N-(4-nitrobenzenesulfonyl)imino] phenyliodinane 1b (p-NO2C6H4SO2N=IPh) is employed instead of the commonly used p-tolyl analog 1a (PhI=NTs). This paper reports the comparison of some nitrene precursors for the copper-catalyzed asymmetric aziridination of olefins, utilizing the olefin as the limiting component and 1.5 equivalents of the nitrene precursor. The aziridine derivatives of several olefins were obtained in moderate to excellent yields and with enantioselectivity up to 95% ee. (C) 1997 Elsevier Science Ltd.
Alkene functionalization for the stereospecific synthesis of substituted aziridines by visible-light photoredox catalysis
A novel strategy involving visible-light-induced functionalization of alkenes for the synthesis of substituted aziridines was developed. The readily prepared N-protected 1-aminopyridinium salts were used for the generation of N-centered radicals. This approach allowed the synthesis of aziridines bearing various functional groups with excellent diastereoselectivity under mild conditions. Moreover, this
Synthesis of Chiral Organocatalysts derived from Aziridines: Application in Asymmetric Aldol Reaction
作者:Shikha Gandhi、Vinod K. Singh
DOI:10.1021/jo8019863
日期:2008.12.5
We report the synthesis of a new series of highly efficient chiral organocatalysts derived via the regio- and stereoselective ring opening of chiral aziridines with azide anions. The catalysts have proved to be very efficient for a direct asymmetric aldolreaction, both with cyclic as well as acyclic ketones in brine with 2 mol % of catalyst loading, and afforded the products in excellent yields (up