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Synthesis 1991; 1991(8): 605-609
DOI: 10.1055/s-1991-26524
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Synthesis of Cyclopropylboronic Acid Esters by Carbene Transfer to 1-Alkenylboronic Acid Esters

Pierre Fontani* , Bertrand Carboni, Michel Vaultier, Gerhard Maas
  • *Groupe de Recherches de Physicochimie Structurale, U.R.A. C.N.R.S. 704, Université de Rennes I, Campus de Beaulieu, F-35042 Rennes Cédex, France and Fachbereich Chemie, Universität Kaiserslautern, Erwin-Schrödinger-Straße, D-6750 Kaiserslautern, Germany
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Publikationsdatum:
29. April 2002 (online)

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Cyclopropylboronic acid esters 2a-j are prepared conveniently and with high stereoselectivity by cycloaddition of carbenes (or carbenoids) to 1-alkenylboronic acid esters. Methylene transfer is achieved either by the Simmons-Smith reaction or with diazomethane/palladium(II) acetate. The latter procedure is susceptible to steric hindrance, but otherwise, product yields are equally good with both methods. Acyl carbene transfer to vinylboronate 1a succeeds with palladium(II) acetate as catalyst, but not with dirhodium tetraacetate or copper(I) triflate. Oxidative cleavage of the C-B bond of (E)-(2-trimethylsilyl- or (E)-(2-(3-chloropropyl) cyclopropyl)boronate with sodium perborate yields cyclopropanols 5d,h.