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Synlett 2008(1): 119-125  
DOI: 10.1055/s-2007-992383
LETTER
© Georg Thieme Verlag Stuttgart · New York

Palladium-Catalyzed Cross-Coupling Reaction of 3-Iodoselenophenes with Boronic Acids

Daniela A. Barancelli, Diego Alves, Patrícia Prediger, Eluza C. Stangherlin, Cristina W. Nogueira, Gilson Zeni*
Laboratório de Síntese, Reatividade, Avaliação Farmacológica e Toxicológica de Organocalcogênios, CCNE, UFSM, Santa Maria, Rio Grande do Sul, CEP 97105-900, Brazil
Fax: +55(55)32208978; e-Mail: gzeni@quimica.ufsm.br;
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Publication History

Received 17 July 2007
Publication Date:
21 November 2007 (online)

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Abstract

The Suzuki cross-coupling of 3-iodoselenophenes with boronic acids in the presence of catalytic amount of palladium salt is described. This cross-coupling reaction proceeded cleanly under mild conditions and was performed with aryl boronic acids bearing electron-withdrawing, electron-donating, and neutral substituents, furnishing the correspondents products in moderate to good yields.

Key words

palladium - Suzuki cross-coupling - selenophene - boronic acid

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General Procedure for the Cross-Coupling Reaction
To a solution of appropriate 3-iodoselenophene (0.25 mmol) in DME (2.5 mL) was added Pd(OAc)2 (0.003g, 5 mol%) and boronic acid (0.35 mmol) under argon. The resulting solution was stirred for 30 min at r.t. After this time, a solution of K3PO4 (1.2 mmol, 0.254 g) in H2O (0.6 mL) was added. The mixture was then heated at reflux during 1-15 h, cooled to r.t., diluted with CH2Cl2 (20 mL), and washed with brine (2 × 20 mL). The organic phase was separated, dried over MgSO4, and concentrated under vacuum. The residue was purified by flash chromatography on silica gel using hexane as eluent. Selected Spectral and Analytical Data for 2,5-(Diphenyl)-3-( p -tolyl)selenophene (3a)
Yield 0.088 g (95%). 1H NMR (400 MHz, CDCl3): δ = 7.59-7.57 (m, 3 H), 7.39-7.35 (m, 2 H), 7.30-7.19 (m, 8 H), 7.10-7.08 (m, 2 H), 2.33 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 148.25, 140.84, 136.57, 136.32, 136.17, 134.71, 129.58, 129.25, 129.21, 129.05, 129.01, 128.92, 128.38, 127.64, 127.19, 126.02, 21.19 ppm. MS: m/z (%) = 373 (100), 281 (65), 296 (45), 220 (42), 128 (72), 91 (65). HRMS: m/z calcd for C23H18Se: 374.0574; found: 374.0580.