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Synlett 2003(13): 2062-2064  
DOI: 10.1055/s-2003-41489
LETTER
© Georg Thieme Verlag Stuttgart · New York

Stereoselective Michael-Aldol Tandem Reaction of Diorganyl Diselenides or Diorganyl Disulfides with Conjugate Alkynones Mediated by Samarium Diiodide

Xingliang Zhenga, Xiaoliang Xua, Yongmin Zhang*a,b
Department of Chemistry, Zhejiang University (Campus Xixi), Hangzhou, 310028, P. R. China
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, P. R. China
Fax: +86(571)88807077; e-Mail: yminzhang@mail.hz.zj.cn;
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Publication History

Received 28 April 2003
Publication Date:
08 October 2003 (online)

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Abstract

Stereoselective Michael addition and Michael-aldol tandem­ reaction of diorganyl diselenides and diorganyl disulfides with conjugate alkynones mediated by samarium diiodide were studied. The reaction temperature was a dominating factor for the stereoselectivity. β-Organylselenoalkenones or β-organylthio­alkenones and γ-organylselenoallylic alcohols or γ-organylthio­allylic alcohols were prepared in good yields.

Key words

stereoselectivity - Michael-aldol tandem reaction - diorgany­l diselenides - diorganyl disulfide - conjugate alkynones

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The Michael-aldol tandem reaction products (Z)-2 and (E)-3 were obtained in good yields. All of the products obtained in this study were new and were fully characterized by 1H NMR, 13C NMR, MS, IR, EA spectroscopic methods.
The Representative Procedure of Michael-Aldol Tandem Reaction (Examples: Preparations of 2b and 3b): The reaction was carried out by adding dibutyl disulfides (0.5 mmol) to SmI2 (1.1 mmol) in THF and the mixture was stirred continuously for 2 h at 60 °C. The tolylphenylacetylenic ketone (1 mmol) and isobutyraldehyde (1 mmol) were added in one portion and were reacted at r.t. or -28 °C. After the reaction was complete checked by TLC. Then 0.1 M HCl was added. The reaction mixture was extracted with Et2O (3 × 20 mL), and the mixed organic layer was washed with sat. Na2S2O3 solution (10 mL) and H2O (10 mL). The combined extracts were dried over anhyd Na2SO4. After the solvent was removed by evaporation under reduced pressure, the crude product was purified by preparative TLC on silica gel (eluent: cyclohexane/EtOAc = 8:1). Compound 2b: light yellow oil. IR (KBr): 3450, 3057, 2958, 2929, 2871, 1655, 1604, 1569, 1487, 1465, 1444, 1408, 1380, 1312, 1179, 746, 648, 600 cm-1. 1H NMR (400 MHz, CDCl3): δ = 7.44-7.46 (d, 2 H, J = 8.0 Hz), 7.22-7.28 (d, 2 H, J = 8.0 Hz), 6.93-7.07 (m, 5 H), 4.97 (s, 1 H), 4.22 (s, 1 H), 2.32 (s, 3 H), 2.23-2.28 (t, 2 H), 1.81-1.83 (m, 1 H), 1.39-1.60 (m, 2H), 1.21-1.28 (m, 2 H), 0.97-1.08 (d, 6 H), 0.72-0.80 (t, 3 H). 13C NMR (100 MHz, CDCl3): δ = 200.48, 146.31, 143.19, 140.63, 137.78, 134.85, 130.23, 129.67, 128.63, 128.43, 127.96, 79.88, 33.91, 32.38, 31.85, 21.51, 19.58, 19.09, 13.38. MS: m/z (%) = 382 (0.70) [M+], 381 (2.22) [M+ - 1], 367 (8.44), 366 (26.86), 365 (100.00) [M+ - 17], 339 (20.65), 325 (1.68), 311 (5.45), 293 (4.55), 247 (15.08), 129 (12.58), 119 (86.85), 91 (48.55), 77 (5.78). Anal. Calcd for C24H30O2S: C, 75.35; H, 7.90. Found C, 75.48; H, 7.85%. Compound 3b: light yellow oil. IR (KBr): 3416, 3056, 2957, 2926, 2870, 1658, 1604, 1572, 1487, 1465, 1443, 1408, 1382, 1312, 1294, 1263, 1187, 1074, 1030, 836, 746, 591 cm-1. 1H NMR (400 MHz, CDCl3): δ = 8.04-8.06 (d, 2 H, J = 8.0 Hz), 7.28-7.50 (m, 7 H, J = 8.0 Hz), 4.96 (s, 1 H), 3.98 (s, 1 H), 2.45 (s, 3 H), 2.08-2.12 (t, 2 H), 1.55-1.64 (m, 1 H), 1.28-1.44 (m, 2 H), 1.17-1.19 (m, 2 H), 0.83-1.01 (d, 6 H), 0.64-0.67 (t, 3 H). 13C NMR (100 MHz, CDCl3): δ = 198.03, 143.95, 141.56, 140.16, 136.48, 135.46, 130.26, 129.72, 129.32, 129.11, 128.33, 79.36, 33.25, 31.91, 31.62, 21.97, 19.75, 19.01, 13.32. MS: m/z (%) = 381 (1.66) [M+ - 1], 367 (0.95), 366 (2.31), 365 (8.53) [M+ - 17], 339 (11.49), 295 (2.92), 293 (2.24), 205 (16.32), 119 (100.00), 77 (9.35). Anal. Calcd for C24H30O2S: C, 75.35; H, 7.90. Found C, 75.52; H, 7.73%.