Rh(II)-Catalyzed asymmetric carbene transfer with ethyl 3,3,3-trifluoro-2-diazopropionate
作者:Paul Müller、Stéphane Grass、Shatrughan P Shahi、Gérald Bernardinelli
DOI:10.1016/j.tet.2004.04.015
日期:2004.5
The asymmetric cyclopropanation of 1,1-diphenylethylene (2) with ethyl 3,3,3-trifluoro-2-diazopropionate (1) in the presence of chiral Rh(II) catalysts affords cyclopropane 3 with yields and enantioselectivities of up to 72 and 40%, respectively. similar results are obtained for asymmetric cyclopropenation of hex-1-yne (4), although enantioselectivity is lower. The cyclopropanation of mono-substituted olefins (8a-8e) with 1 leads to cis/trans-mixtures of cyclopropanes 9a-9e with a maximum ee of 75% for 4-methoxystyrene (8c). (C) 2004 Published by Elsevier Ltd.