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Formal enantioselective Michael addition with umpolung of reactivity
1Ludwig-Maximilians-Universität München Department of Chemie Butenandtstrasse 5-13, 81377 München, Germany, Fax: (+49) 89-2180-7680.
Angewandte Chemie (International Ed. in English)
|August 31, 2002
Abstract:
By a sequence comprising asymmetric hydroboration, boron-zinc exchange, and transmetalation with copper, allylations, alkynylations, and allenylations of unsaturated ketals or acetals can be performed with good enantioselectivities (see scheme, (-)-IpcBH2 =(-)-isopinocampheylborane, TMS=Me3 Si). The products correspond to a formal Michael addition with inversion of polarity.