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Synlett 2006(20): 3492-3494  
DOI: 10.1055/s-2006-958432
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Stereoselective Synthesis of (E)-α-Stannylvinyl Sulfones via Palladium-­Catalyzed Hydrostannylation of Acetylenic Sulfones

Mingzhong Cai*, Guiqin Chen, Wenyan Hao, Dong Wang
Department of Chemistry, Jiangxi Normal University, Nanchang 330022, P. R. of China
Fax: +86(791)8517500; e-Mail: mzcai@jxnu.edu.cn;
Further Information

Publication History

Received 5 August 2006
Publication Date:
08 December 2006 (online)

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Abstract

Palladium-catalyzed hydrostannylation of acetylenic sulfones with Bu3SnH in benzene at room temperature afforded stereoselectively (E)-α-stannylvinyl sulfones in good to high yields.

Key words

hydrostannylation - acetylenic sulfone - palladium - (E)-α-stannylvinyl sulfone - stereoselective synthesis

14

Typical Procedure for Hydrostannylation Reaction.
A 25-mL, two-necked round-bottomed flask equipped with a magnetic stir bar and argon was charged sequentially with 1-butyl-2-(phenylsulfonyl)ethyne (1a, 1 mmol), benzene (4 mL), Pd(PPh3)4 (0.01 mmol) and Bu3SnH (1.05 mmol). The mixture was stirred at r.t. for 4 h. After removal of the solvent under reduced pressure, the residue was diluted with light PE (20 mL) and filtered to remove the palladium catalyst. The resulting solution was concentrated under vacuum and the residue was purified by flash chromatography on silica gel eluting with light PE.
Selected spectral and analytical data for 2a: yield 0.462 g (90%). 1H NMR (400 MHz, CDCl3): δ = 7.86-7.84 (m, 2 H), 7.56-7.48 (m, 3 H), 6.28 (t, J = 7.2 Hz, 1 H), 2.40-2.36 (m, 2 H), 1.56-1.48 (m, 6 H), 1.38-1.29 (m, 6 H), 1.22-1.15 (m, 4 H), 1.11-1.06 (m, 6 H), 0.90 (t, J = 7.2 Hz, 9 H), 0.80 (t, J = 7.2 Hz, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 157.4, 149.0, 143.5, 132.5, 128.8, 127.1, 31.0, 30.6, 28.8, 27.3, 22.3, 13.8, 13.7, 11.4 ppm.

19

Typical Procedure for Stille Coupling Reaction.
(E)-1-(Tributylstannyl)-1-(phenylsulfonyl)-1-hexene (2a, 1 mmol) and allyl bromide 3a (1.1 mmol) were dissolved in DMF (10 mL) under Ar at r.t. The compounds Pd(PPh3)4 (0.05 mmol) and CuI (0.75 mmol) were then added. The mixture was stirred at r.t. and monitored by TLC for the disappearance of the starting organostannane. Then it was diluted with Et2O (40 mL) and the organic layer was washed with aq NH4Cl (10 mL) and H2O (20 mL), and dried over MgSO4. The solvent was removed under reduced pressure and the residue purified by column chromatography on silica gel eluting with a mixture of Et2O and light PE (1:6).
Selected spectral and analytical data for 4a: yield 0.219 g (83%). 1H NMR (400 MHz, CDCl3): δ = 7.90-7.87 (m, 2 H), 7.61-7.51 (m, 3 H), 6.03 (t, J = 7.6 Hz, 1 H), 5.73-5.63 (m, 1 H), 5.11-5.04 (m, 2 H), 3.08-3.06 (m, 2 H), 2.68-2.60 (m, 2 H), 1.37-1.25 (m, 4 H), 0.88 (t, J = 7.2 Hz, 3 H) ppm. 13C NMR (100 MHZ, CDCl3): δ = 144.5, 141.5, 138.9, 134.3, 133.2, 129.1, 127.4, 118.0, 36.8, 31.3, 28.4, 22.3, 13.9 ppm.