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Synlett 2008(3): 443-447  
DOI: 10.1055/s-2008-1032070
LETTER
© Georg Thieme Verlag Stuttgart · New York

Preparation of α-Bromoacrylates: One-Pot Procedure for the Synthesis of Conjugated Acetylenic Carboxylates from Aldehydes with Ph3P/Br3CCO2Et

Joong-Gon Kima, Dong Ho Kangb, Doo Ok Jang*b,c
a Biotechnology Division, Hanwha Chemical R&D Center, Daejeon 305345, Korea
b Department of Chemistry, Yonsei University, Wonju 220710, Korea
c Center for Bioactive Molecular Hybrids, Yonsei University, Seoul 120749, Korea
Fax: +82(33)7602182; e-Mail: dojang@yonsei.ac.kr;
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Publication History

Received 17 November 2007
Publication Date:
23 January 2008 (online)

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Abstract

We have established the optimal conditions for the Wittig reaction for synthesizing α-bromoacrylates with a high selectivity, and developed a simple and efficient one-pot procedure for preparing various conjugated acetylenic carboxylates in moderate to high yields.

Key words

α-bromoacrylate - conjugated acetylenic carboxylate - aldehyde - Wittig reaction

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Typical Procedure: To a mixture of Ph3P (1.31 g, 5 mmol) and Br3CCO2Et (0.81 g, 2.5 mmol) in THF (6 mL) under argon was added a solution of p-nitrobenzaldehyde (0.19 g, 1.25 mmol). After heating at reflux for 3 h, the reaction mixture was cooled to r.t. A mixture of NaNH2 (0.78 g, 1.88 mmol) and t-BuOK (0.21 g, 1.88 mmol) in THF (3 mL) was added to the reaction mixture. After stirring at r.t. for 2 h, the mixture was diluted with Et2O, washed with brine, and dried over anhyd MgSO4. After evaporation of the solvent, the residue was separated by column chromatography on silica gel (hexane-EtOAc, 9:1) affording the product in 82% yield; mp 122-123 °C (lit. [3d] 120-121 °C). 1H NMR (300 MHz, CDCl3): δ = 8.31 (d, J = 9.0 Hz, 2 H), 7.78 (d, J = 9.0 Hz, 2 H), 4.37 (q, J = 7.0 Hz, 2 H), 1.38 (t, J = 7.0 Hz, 3 H).