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Synlett 2006(15): 2492-2494  
DOI: 10.1055/s-2006-950406
LETTER
© Georg Thieme Verlag Stuttgart · New York

Sm/I2-Mediated Selective Cleavage of the S-S or C-S Bonds of Sodium (Z)-Allyl Thiosulfates in Aqueous Media: Selective Formation of Di(Z-allyl) Disulfides or (2E)-Methyl Cinnamic Esters

Yunkui Liua, Hui Zhenga, Danqian Xua, Zhenyuan Xu*a, Yongmin Zhang*b,c
a State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang University of Technology, Hangzhou, 310014, P. R. of China
b Department of Chemistry, Zhejiang University, Xi-xi Campus, Hangzhou, 310028, P. R. of China
c State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, P. R. of China
Fax: +86(571)88320609; e-Mail: chrc@zjut.edu.cn;
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Publication History

Received 31 May 2006
Publication Date:
08 September 2006 (online)

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Abstract

Selective cleavage of the S-S or C-S bonds in sodium (Z)-allyl thiosulfates in the presence of a Sm/I2-system was achieved to form the corresponding di(Z-allyl) disulfides or (2E)-methyl cinnamic esters in moderate to good yields in aqueous ­media.

Key words

selective cleavage - sodium (Z)-allyl thiosulfates - di(Z-allyl) disulfides - (2E)-methyl cinnamic esters - samarium metal

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One-Pot Synthesis of Di( Z -allyl) Disulfides or (2 E )-Methyl Cinnamic Esters; General Procedure: In a 25-mL flask were added Na2SSO3·5H2O (0.25 g, 1.0 mmol), Baylis-Hillman acetate 1 (1.0 mmol), and anhyd MeOH (15 mL). The mixture was stirred at r.t. for 4-8 h until the sodium (Z)-allyl thiosulfates were formed.7 MeOH was removed and THF (20 mL) was added under an inert atmosphere. Then Sm (0.15 g, 1 mmol) and a trace amount of I2 were added to the resulting mixture followed by the addition of a sat. aq solution of NH4Cl (4 mL) dropwise. The mixture was stirred at r.t. for the time given in Table [1] . Upon completion, the reaction mixture was quenched with dil. HCl (5%, 15 mL), extracted with Et2O (2 × 30 mL), washed with brine (15 mL), and dried over MgSO4. After evaporation of the solvent, the residue was purified by chromatography [cyclohexane-EtOAc (9:1) (R = alkyl groups) or cyclohexane-EtOAc (6:1) (R = aryl groups)].

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According to NOESY experiments, there is no NOE correlation between the signal of the internal olefin proton and the allylic methylene protons.

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Compound 3a: IR (film): 1719, 1642 cm-1. 1H NMR (CDCl3, 400 MHz): δ = 1.10 (t, 6 H, J = 7.2 Hz), 2.30-2.37 (m, 4 H), 3.69 (s, 4 H), 3.77 (s, 6 H), 6.93 (t, 2 H, J = 7.2 Hz). 13C NMR (CDCl3, 100 MHz): δ = 13.34, 22.47, 35.00, 51.85, 127.44, 147.90, 166.97. MS (70 eV): m/z (%) = 318 (M+). Anal. Calcd for C14H22O4S2: C, 52.80; H, 6.96. Found: C, 53.23; H, 6.90.
Compound 3b: IR (film): 1721, 1642 cm-1. 1H NMR (CDCl3, 400 MHz): δ = 0.88 (t, 6 H, J = 7.2 Hz), 1.25-1.47 (m, 20 H), 2.32 (q, 4 H, J = 7.2 Hz), 3.70 (s, 4 H), 3.77 (s, 6 H), 6.95 (t, 2 H, J = 7.2 Hz). 13C NMR (CDCl3, 100 MHz): δ = 22.59, 28.84, 29.09, 29.19, 29.24, 29.32, 31.71, 35.29, 51.89, 127.92, 146.78, 166.99. MS (70 eV): m/z (%) = 458 (M+). Anal. Calcd for C24H42O4S2: C, 62.84; H, 9.23. Found: C, 62.51; H, 9.28.
Compound 3c: IR (film): 1716, 1643 cm-1. 1H NMR (CDCl3, 400 MHz): δ = 2.62 (q, 4 H, J = 8.0 Hz), 2.78 (t, 4 H, J = 8.0 Hz), 3.62 (s, 4 H), 3.72 (s, 6 H), 6.98 (t, 2 H, J = 8.0 Hz), 7.19-7.32 (m, 10 H). 13C NMR (CDCl3, 100 MHz): δ = 31.32, 35.23, 35.38, 52.29, 126.49, 128.66, 128.77, 128.86, 141.01, 145.43, 167.13. MS (70 eV): m/z (%) = 470 (M+). Anal. Calcd for C26H30O4S2: C, 66.35; H, 6.42. Found: C, 66.72; H, 6.48.