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A novel chro
miu
m-pro
moted alkyl- and silyl cyclopropanation of (
E)- or (
Z)-
mages/gifchars/alpha.gif" BORDER=0>,
mages/gifchars/beta2.gif" BORDER=0 ALIGN="
middle">-unsaturated a
mides in which the C-C double bond is di-, ortrisubstituted is described. This process takes place with total stereospecificity, and the new stereogenic center is generated with high or totalstereoselectivity. A
mechanis
m is proposed to explain the cyclopropanation reaction.