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Synlett 2005(19): 2953-2957  
DOI: 10.1055/s-2005-918947
LETTER
© Georg Thieme Verlag Stuttgart · New York

The Reaction of Alkylenecyclopropanes and Diethyl Phosphite: A Novel ­Method for the Preparation of Diethyl 3,4-Dihydro-2-naphthylphosphonates and 3-Butenyl Ethyl Phosphates

Xian Huang*a,b, Lei Yua
a Department of Chemistry, Zhejiang University (Xixi Campus), Hangzhou 310028, P. R. of China
b State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. of China
Fax: +86(571)88807077; e-Mail: huangx@mail.hz.zj.cn;
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Publication History

Received 8 July 2005
Publication Date:
12 October 2005 (online)

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Abstract

AIBN-mediated addition of alkylidenecyclopropanes to diethyl phosphite produces diethyl-3,4-dihydro-2-naphthylphosphonates in moderate yields. When the reaction was carried out without AIBN in the presence of 5% water, 3-butenyl ethyl phosphites were obtained.

Key words

phosphates - phosphorus - radicals - radical reactions - methylenecyclopropanes

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Diethyl 3,4-Dihydro-2-naphthylphosphonates 3; Typical Procedure. A soln of AIBN (0.049 g, 0.3 mmol) in diethyl phosphate (2 mL) was added very slowly (1 h) into(diphenylmethylene)cyclopropane (1a, 0.062 g, 0.3 mmol) at 130 °C under a nitrogen atmosphere. After the addition of AIBN, the mixture was heated for an extra 30 min at the same temperature. The excess diethyl phosphite was evaporated under vacuum and recovered, the residue was subjected to preparative TLC (petroleum ether-EtOAc, 3:1) to afford 3a (0.075g, 73%). Other diethyl 3,4-dihydro-2-naphthylphosphonates were prepared in a similar way.
Oil. IR (KBr): 2892, 1239, 1053, 1027, 820 cm-1. 1H NMR (400 MHz, CDCl3): δ = 7.35-7.41 (m, 3 H), 7.24-7.26 (m, 2 H), 7.19-7.20 (m, 2 H), 7.04-7.06 (m, 1 H), 6.67 (d, J = 7.6 Hz, 1 H), 3.721-3.862 (m, 4 H), 2.90 (t, J = 8.0 Hz, 2 H), 2.69-2.75 (m, 2 H), 1.13 (t, J = 7.2 Hz, 6 H). 13C NMR (100 MHz, CDCl3): δ = 16.1 (d, 3 J P-C = 6.7 Hz), 25.1 (d, 3 J P-C = 10.1 Hz), 27.8 (d, 2 J P-C = 6.9 Hz), 61.3 (d, 2 J P-C = 6.6 Hz), 124.5 (d, 1 J P-C = 184.3 Hz), 126.4, 127.2, 127.5, 127.7, 127.8, 128.1, 128.9, 129.6, 129.7, 135.5 (d, 3 J P-C = 19.1 Hz), 137.0, 138.8 (d, 2 J P-C = 7.9 Hz), 149.9 (d, 3 J P-C = 10.0 Hz). MS (70 eV, EI): m/z (%) = 342 (M+, 16.8), 341 (M+ - 1, 100.0).

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3-Butenyl Ethyl Phosphite 4a. Under a nitrogen atmosphere (diphenylmethylene)cyclopropane (1a, 0.062 g, 0.3 mmol) in diethyl phosphite (2 mL) and H2O (0.1 mL) was heated at 150 °C. The reaction was monitored by TLC (petroleum ether-EtOAc, 2:1). After 1 h, excess diethyl phosphite was evaporated under vacuum and recovered, the residue was subjected to preparative TLC (petroleum ether-EtOAc, 3:1) to afford 4a (0.060 g, 63%). Other 3-butenyl ethyl phosphites were prepared in a similar way.
Oil. IR (KBr): 2982, 1258, 1034, 976, 766, 701 cm-1. 1H NMR (400 MHz, CDCl3): δ = 6.81 (d, J = 695.6 Hz, 1 H), 7.16-7.40 (m, 10 H), 6.09 (t, J = 7.2 Hz, 1 H), 4.09-4.15 (m, 4 H), 2.50-2.55 (m, 2 H), 1.33 (t, J = 6.8 Hz, 3 H). 13C NMR (100 MHz, CDCl3): δ = 16.2 (d, 3 J P-C = 6.3 Hz), 30.9 (d, 3 J P-C = 6.4 Hz), 61.8 (d, 2 J P-C = 6.2 Hz), 65.1 (d, 2 J P-C = 5.8 Hz), 123.5, 127.2, 127.3, 128.1, 128.3, 129.7, 139.5, 142.0, 144.7. MS (70 eV, EI): m/z (%) = 316 (M+, 2.0), 207 (100.0), 206 (79.3).