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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
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14b Mouriès, V.; Delouvrié, B.; Lacôte, E.; Fensterbank, L.; Malacria, M. Eur. J. Org. Chem. 2002, in press.
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16a The cis relative stereochemistry was assigned by analogy with our previous work, see ref.10 and: Devin P.
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16b Spectral data for 13. IR(neat): 3350, 3080, 2950, 1640, 1250 cm-1; 1H NMR (400 MHz, CDCl3) δ 4.40 (m, 1 H, CH-OH), 2.31 (m, 2 H, CH
2 cyclopentenol + CHCH3), 1.76 (d, J = 13.8 Hz, 1 H, CH
2Si), 1.64 (d, J = 13.8 Hz, 1 H, CH
2Si), 1.34 (m, 1 H, CH cyclopropane), 1.26 (m, 1 H, CH
2 cyclopentenol), 1.11 (d, J = 6.6 Hz, 3 H, CH
3
), 0.70 (m, 2 H, cyclopropane), 0.55 (m, 1 H, cyclopropane), 0.41 (m, 1 H, cyclopropane), 0.04 [9 H, Si(CH
3)3]; 13C NMR (100 MHz, CDCl3) δ 141.2 (C, C=C), 137.1 (C, C=C), 79.9 (CH, CH-OH), 41.9 (CH2, cyclopentenol), 38.6 (CH, cyclopentenol), 23.0 (CH3), 16.4 (CH2, CH2Si), 9.7 (CH, cyclopropane), 5.8 (CH2, cyclopropane), 5.2 (CH2, cyclopropane), -0.4 [3 CH3, Si(CH3)3]. Anal. Calcd. for C13H24OSi: C, 69.58; H, 10.78. Found: C, 69.55; H, 10.89.
17a We thank one of the referees for bringing to our attention that the rate constant of a 5-exo vinyl radical cyclization has been estimated to be: 3.2 ¥ 108 s-1 at 60 °C: Beckwith ALJ.
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17c Although the Beckwith system cannot directly be compared to the system studied herein (different substitution pattern), this data could suggest an intrinsic faster cyclization of the vinyl radical, thus contributing significantly to the observed effect.
18 An alkoxy group reduces the activation barrier for the ring opening of cyclopropylcarbinyl radicals, see: Martinez FN.
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