Synlett 2002(1): 0176-0178
DOI: 10.1055/s-2002-19345
LETTER
© Georg Thieme Verlag Stuttgart · New York

Cyclopropanation of Allylic Alcohols using Substituted Haloalkylzinc Reagents: Synthesis of gem-Dimethylcyclopropanes

André B. Charette*, Nicole Wilb
Département de Chimie, Université de Montréal, P.O. Box 6128, Station Downtown, Montréal, Québec, H3C 3J7, Canada
e-Mail: andre.charette@umontreal.ca;
Further Information

Publication History

Received 18 July 2001
Publication Date:
01 February 2007 (online)

Abstract

gem-Dimethylcyclopropanes were obtained by a cyclopropanation of allylic alcohols and ethers using a mixture of diethylzinc and 2,2-diiodopropane in 53-96% yields. Enantioenriched gem-dimethylcyclopropanes were also synthesized using a glucose-derived auxiliary.

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Charette, A. B.; Wilb, N. unpublished results.

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Typical Experimental Procedure: To a solution of the alkene (0.4 mmol) in anhyd CH2Cl2 (16 mL) at -10 °C was added dropwise Et2Zn (1.6 mmol, 1.2 mmol in the case of the ethers). After 10 min of stirring at that temperature, 2,2-diiodopropane (1.6 mmol, 1.2 mmol in the case of the ethers) was added dropwise over 2 min and the solution was stirred overnight at r.t. The formation of a precipitate (probably ZnI2) was rapidly observed. The solution was then diluted with ether (10 mL) and washed with 10% aq HCl (10 mL), sat. aq Na2SO3 (10 mL), brine (10 mL), dried over MgSO4, filtered and concentrated under reduced pressure.The crude cyclopropanes were purified by flash chromatography on silica gel.