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Synlett 2002(6): 0923-0926
DOI: 10.1055/s-2002-31915
LETTER
© Georg Thieme Verlag Stuttgart · New York

New Elements in the Reactivity of α-Cyclopropyl Vinyl Radicals

Emily Mainetti, Louis Fensterbank*, Max Malacria*
UMR 7611, Université Pierre et Marie Curie, 4, Place Jussieu, b. 229, 75005 Paris, France
Fax: +33(1)44277360; e-Mail: fensterb@ccr.jussieu.fr; e-Mail: malacria@ccr.jussieu.fr;
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Publication History

Received 22 March 2002
Publication Date:
07 February 2007 (online)

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Abstract

The reactivity of the α-cyclopropyl vinyl radical has been examined through the use of propargylic bromomethyldime­thylsilyl ethers bearing a cyclopropyl group on the acetylenic moiety. With unsubstituted precursors, allenes can be obtained. With appropriate trapping possibilities (5-exo cyclization or hydrogen transfer), the cyclopropyl moiety on the vinyl radical is retained.

Key words

vinyl radicals - cyclizations - ring opening - hydrogen transfer - cyclopropanes

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13

Spectroscopic data for 10. IR(neat): 2960, 1960, 1750, 1450, 1370, 1270 cm-1; 1H NMR (200 MHz, CDCl3) δ 5.21 (m, 1 H, vinyl), 4.48 (t, J = 2.0 Hz, 2 H, CH 2 O), 3.75 (s, 3 H, CO2CH 3 ), 1.97 (quint, J = 7.4 Hz, 2 H, CH 2 CH3), 1.32 (mAB, 2 H, CH 2 Si), 0.97 (t, J = 7.4 Hz, 3 H, CH 3 ), 0.02 (s, 9 H, Si(CH 3 )3); 13C NMR (50 MHz, CDCl3) δ 201.8 (C, C=C=CH), 155.8 (C, C=O), 97.4 (C, C=C=CH), 94.8 (CH, C=C=CH), 70.1 (CH2, CH2O), 54.8 (CH3, CO2 CH3), 22.5 (CH2, CH2CH3), 18.2 (CH2, CH2Si), 13.6 (CH3), -1.3 (3 CH3, Si(CH3)3). Anal. Calcd. for C12H22O3Si: C, 59.46; H, 9.15. Found: C, 59.34; H, 9.35.