Formal enantioselective Michael addition with umpolung of reactivity

E Hupe; P Knochel

doi:10.1002/1521-3773(20010817)40:16<3022::AID-ANIE3022>3.0.CO;2-W

Formal enantioselective Michael addition with umpolung of reactivity

Angew Chem Int Ed Engl. 2001;40(16):3022-5. doi: 10.1002/1521-3773(20010817)40:16<3022::AID-ANIE3022>3.0.CO;2-W.

Authors

E Hupe¹, P Knochel

Affiliation

¹ Ludwig-Maximilians-Universität München Department of Chemie Butenandtstrasse 5-13, 81377 München, Germany, Fax: (+49) 89-2180-7680.

PMID: 12203636
DOI: 10.1002/1521-3773(20010817)40:16<3022::AID-ANIE3022>3.0.CO;2-W

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.

Keywords: Michael addition; asymmetric synthesis; hydroboration; umpolung; zinc.