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Synthesis 2008(11): 1717-1724  
DOI: 10.1055/s-2008-1067020
PAPER
© Georg Thieme Verlag Stuttgart · New York

Microwave-Irradiated Transition-Metal Catalysis: Rapid and Efficient Dehydrative Carbon-Carbon Coupling of Alcohols with Active Methylenes

Srinivasarao Arulananda Babua,b, Makoto Yasudaa,b, Yasunori Tsukaharab, Tomohisa Yamauchib, Yuji Wadab,c, Akio Baba*a,b
a Department of Applied Chemistry, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
Fax: +81(6)68797387; e-Mail: baba@chem.eng.osaka-u.ac.jp;
b Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
c Department of Applied Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1-S1-43 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
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Publication History

Received 28 January 2008
Publication Date:
11 April 2008 (online)

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Abstract

A rapid and highly productive synthetic microwave-irradiation­ protocol for transition-metal-catalyzed carbon-carbon coupling of a wide range of benzylic/allylic alcohols with β-diones, β-keto esters, and dialkyl malonates is reported. In a representative screening of transition-metal catalysts, salts of Zn, Cu, Fe, Sc, Ru, Pt, Ta, and Mo were found to furnish the coupling products. In light of the results obtained, among all of these catalysts copper(II) triflate was found to be relatively more effective compared to other catalysts even in the case of a less reactive benzyl alcohol or diester. Interestingly, these MW-irradiated reactions are performed in a more or less MW-transparent medium, such as toluene, having a very low tanδ, or under neat conditions.

Key words

alcohols - alkylations - catalysis - C-C coupling - dicarbonyl compounds - microwave irradiation - transition metals