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A novel chromium-promoted alkyl- and silyl cyclopropanation of (
E)- or (
Z)-
ges/
gifchars/alpha.
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ges/
gifchars/beta2.
gif" BORDER=0 ALIGN="middle">-unsaturated amides in which the C-C double bond is di-, ortrisubstituted is described. This process takes place with total stereospecificity, and the new stereo
genic center is
generated with hi
gh or totalstereoselectivity. A mechanism is proposed to explain the cyclopropanation reaction.