Synlett 2005(14): 2239-2241  
DOI: 10.1055/s-2005-872247
LETTER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Chiral Methylenecyclopropane Derivatives

Elinor Zohar, Amnon Stanger, Ilan Marek*
Department of Chemistry, Institute of Catalysis Science and Technology, The Lise Meitner-Minerva Center for Computational Quantum Chemistry Technion-Israel Institute of Technology, Haifa 32 000, Israel
Fax: +972(4)8293709; e-Mail: chilanm@tx.technion.ac.il;
Further Information

Publication History

Received 7 June 2005
Publication Date:
26 July 2005 (online)

Abstract

Diastereoisomerically pure methylenecyclopropane and methylenecyclopropane carbinol derivatives were easily prepared, in a single-pot operation, from 1,1,2-tribromocyclopropane via a three-component reaction.

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Stanger, A.; Zohar, E.; Marek, I. unpublished results.

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Typical Experimental Procedure.
t-BuLi (1.7 M solution in pentane, 18.7 mmol) was added over 5 min to a stirred solution of 3 (4.67 mmol) in Et2O (20 mL) at -80 °C. The mixture was allowed to reach 20 °C and was cooled down to -60 °C after 30 min. To the cooled mixture, a THF (20 mL) solution of (-)-menthyl p-toluene-sulfinate (2.33 mmol) was added. After being warmed to -50 °C during a 2 h period, the mixture was stirred for additional 2 h at the same temperature. Electrophiles (8 mmol) were added at the same temperature and then the mixture was allowed to warm slowly to 25 °C and stirred overnight. Then, sat. NH4Cl was added, the aqueous layer was extracted with Et2O (3 × 20 mL) and the combined organic layers were washed with H2O (2 × 20 mL), dried over MgSO4 and the solvent was removed under reduced pressure. Purification by column chromatography on silica gel (eluent: hexane-EtOAc, 6:1) gave the corresponding methylenecyclopropane in indicated yields.