Synlett 2002(3): 0443-0446
DOI: 10.1055/s-2002-20461
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Simple and Efficient Conversion of Tertiary Cyclopropanols to 2-Substituted Allyl Halides

Yurii Yu. Kozyrkov, Oleg G. Kulinkovich*
Department of Organic Chemistry, Belarusian State University, 4, Skoriny av., Minsk, 220050, Belarus
Fax: +375(17)2264998; e-Mail: kulinkovich@bsu.by;
Further Information

Publication History

Received 18 December 2001
Publication Date:
05 February 2007 (online)

Abstract

Readily available sulphonates of tertiary cyclopropanols are converted into 2-substituted allyl bromides in high yields under the action of magnesium bromide in diethyl ether. Magnesium chloride, aluminium chloride and titanium tetrachloride also induce effectively the transformation of cyclopropyl sulphonates into the corresponding allyl chlorides.

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Typical Procedure: A solution of 1-hexylcyclopropyl methanesulfonate 2a 7.65 g (35 mmol) in 10 mL Et2O was added slowly into MgBr2 (52 mmol) solution (prepared from 1.26 g magnesium turnings and 4.5 mL 1,2-dibromoethane in 30 mL Et2O) at r.t. When the reaction was completed (control by TLC), water was added to the mixture until precipitate was dissolved. Water layer was extracted with Et2O, washed with 5% NaCl solution and dried over Na2SO4. After evaporation of the solvent, the resulting crude product was purified by column chromatography, using petroleum ether eluent and silica gel (Merck 70-230), yielding 6.82 g (95%) of pure allyl halide 3.

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Entry 11: 1H NMR (200 MHz, CDCl3) δ = 0.60-0.74 (m, 1 H), 0.80-0.92 (m, 1 H), 1.06-1.22 (m, 2 H), 1.74 (d, J = 6.5 Hz, 3 H), 2.09 (dd, J 1 = 15 Hz, J 2 = 8 Hz, 1 H), 2.45 (s, 3 H), 2.49 (dd, J 1 = 15 Hz, J 2 = 6 Hz, 1 H), 4.28-4.50 (m, 1 H), 7.35 (d, J = 8 Hz, 2 H), 7.77 (d, J = 8 Hz, 2 H). Entry 19: 1H NMR (200 MHz, CDCl3) δ = 0.92 (t, J = 6 Hz, 1 H), 1.04-1.40 (m, 2 H), 1.58 (dd, J 1 = 12 Hz, J 2 = 8 Hz, 1 H), 1.66-2.06 (m, 3 H), 2.10-2.44 (m, 2 H), 3.02 (s, 3 H).

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Entry 11: 1H NMR (200 MHz, CDCl3): δ = 1.76 (d, J = 6.5 Hz, 3 H), 2.61-2.89 (m, 2 H), 4.01 (s, 2 H), 4.17-4.28 (m, 1 H), 5.08 (d, J = 1 Hz, 1 H), 5.32 (s, 1 H). n D 20 = 1.5235. Entry 19: 1H NMR (200 MHz, CDCl3): δ = 1.86-2.06 (m, 2 H), 2.28-2.50 (m, 4 H), 4.08 (s, 1.8 H), 4.88-4.95 (m, 0.1 H), 5.07 (s, 0.1 H), 5.30 (s, 0.1 H), 5.78 (s, 0.9 H).