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Synthesis 2005(19): 3186-3188  
DOI: 10.1055/s-2005-918469
SHORTPAPER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Enantiopure Aminocyclopropanes by Diastereoselective Addition of a Chiral Amino Substituted Organozinc Carbenoid to Alkenes

Guillaume Bégisa, Tom D. Shepparda, David E. Cladingboelb, William B. Motherwell*a, Derek A. Tochera
a Department of Chemistry, Christopher Ingold Laboratories, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
b AstraZeneca R&D Charnwood, Bakewell Road, Loughborough, LE11 5RH, UK
Fax: +44(20)76797524; e-Mail: w.b.motherwell@ucl.ac.uk;
Further Information

Publication History

Received 6 September 2005
Publication Date:
14 November 2005 (online)

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Abstract

The synthesis of enantiopure aminocyclopropanes is reported, via direct aminocyclopropanation of alkenes with a zinc carbenoid containing a chiral auxiliary. The methodology was applied to the synthesis of a protected aminocyclopropane present in the immunosuppressant Belactosin A.

Key words

alkenes - carbenoids - chiral auxiliaries - electrophilic addition - zinc

7

CCDC Nos. 282755 and 282756 contain the crystallographic data for 14 and 16. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

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The enantiomeric excess of alkene 21 was > 97% by chiral HPLC after a single recrystallisation.

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Yield calculated by 1H NMR, the cyclopropane product was contaminated with oxazolidinone 5. The stereochemistry was assigned analogously on the basis of 1H NMR coupling constants.

13

Traces of acid and water in CDCl3 can cause partial degradation to the N-formyl derivative.