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Synlett 2005(19): 2981-2983  
DOI: 10.1055/s-2005-921888
LETTER
© Georg Thieme Verlag Stuttgart · New York

Radical Addition Reactions of Diphenylphosphine Sulfide

Andrew F. Parsons*a, David J. Sharpea, Philip Taylorb
a Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
Fax: +44(1904)432516; e-Mail: afp2@york.ac.uk;
b ICI Paints plc, Wexham Road, Slough, SL2 5DS, UK
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Publication History

Received 21 September 2005
Publication Date:
04 November 2005 (online)

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Abstract

Radical additions of diphenylphosphine sulfide [Ph2P(S)H] to various C=C bonds offers a general, mild and ­efficient approach to alkyl(diphenyl)phosphine sulfides.

Key words

radical reaction - phosphorus hydride - C=C bonds

3

Pantazis, D.; McGrady, J. E. unpublished results.

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Performed in a CEM Focused Microwave Synthesis System.

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All new compounds gave consistent spectral and HRMS data.

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Typical Procedure. To diphenylphosphine sulfide (0.327 g, 3 equiv, 1.5 mmol) in a N2 flushed flask was added non-degassed dioxane (2 mL), followed by methyl methacrylate (0.053 mL, 0.5 mmol). Then, Et3B (1 M solution in hexane, 0.15 mL, 0.3 equiv, 0.15 mmol) was added and the reaction was left to stir for 4 h. After this time a further portion of Et3B (1 M solution in hexane, 0.15 mL, 0.3 equiv, 0.15 mmol) was added, and the mixture was left to stir for 16 h. The reaction mixture was then concentrated in vacuo to afford the crude product. Following column chromatography (4:1, PE-EtOAc), methyl 3-(diphenylphosphorothioyl)-2-methylpropanoate (9) was isolated as a colourless oil (0.147 g, 92%); R f = 0.2 (4:1, PE-EtOAc). IR (thin film): νmax = 3054 (m), 2975 (m), 2949 (m), 1731 (s, C=O), 1436 (s, P-Ph), 1309 (m), 1274 (m), 1211 (s), 1158 (s), 1102 (s), 1027 (m), 998 (m) cm-1.
1H NMR (400 MHz, CDCl3): δ = 7.91-7.80 (4 H, m, 4 × CH Ar), 7.54-7.41 (6 H, m, 6 × CH Ar), 3.46 (3 H, s, O-CH 3), 3.21-3.08 [2 H, m, P(S)CH 2-CH], 2.52-2.41 [1 H, m, P(S)CH2-CH], 1.18 (3 H, d, J = 7 Hz, CH2-CH-CH 3).
13C NMR (100.6 MHz, CDCl3): δ = 175.8 (d, 3 J C-P = 9.5 Hz, O=C-O-CH3), 133.1 (d, 1 J C-P = 80.5 Hz, C q Ar), 132.3 (d, 1 J C-P = 80.5 Hz, C q Ar), 131.6 (d, 4 J C-P = 3.0 Hz, CH Ar), 131.5 (d, 4 J C-P = 3.0 Hz, CH, Ar), 131.3 (d, 2 J C-P = 10.5 Hz, 2 × CH Ar), 131.0 (d, 2 J C-P 10.0 Hz, 2 × CH Ar), 128.7 (d, 3 J C-P 12.0 Hz, 2 × CH Ar), 128.5 (d, 3 J C-P = 12.0 Hz, 2 × CH Ar), 51.9 (O-CH3), 35.5 [d, 1 J C-P = 57 Hz, P(S)CH2], 34.3 [d, 2 J C-P = 1 Hz, P(S)CH2-CH], 19.4 (d, 3 J C-P = 8.5 Hz, CH2-CH-CH3). 31P NMR (161.9 MHz, CDCl3): δ = 41.3 [Ph2 P(S)]. MS (CI, NH3): m/z (%) = 319 (100), 218 (17). HRMS: m/z calcd for C17H19O2PS: [M + H+] 319.0922 (0.2 ppm); found: [M + H+] 319.0921.

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Deprotonation of Ph2P(S)H and addition to electron-poor alkenes has been reported previously (see ref. 4).