Synthesis 2011(19): 3138-3142  
DOI: 10.1055/s-0030-1260169
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

N-Heterocyclic Carbene/Pd(II)/1-Methylimidazole Complex Catalyzed Suzuki-Miyaura Coupling Reaction of Aryl Chlorides in Water

Xia-Xia Zhou, Li-Xiong Shao*
College of Chemistry and Materials Engineering, Wenzhou University, Chashan University Town, Wenzhou, Zhejiang Province 325035, P. R. of China
Fax: +86(577)88373111; e-Mail: Shaolix@wzu.edu.cn;
Further Information

Publication History

Received 21 May 2011
Publication Date:
10 August 2011 (online)

Abstract

A well-defined N-heterocyclic carbene (NHC)/palladium chloride/imidazole complex exhibited high catalytic activity in the Suzuki-Miyaura coupling reactions of aryl or heteroaryl chlorides performed in water. Under optimal conditions, all reactions gave the desired coupling products in good to high yields.

9

Although NaOH is a suitable base for the coupling of chlorobenzene (2a) with 4-methoxyphenylboronic acid (3a), the generality using NaOH as the base is not as good as that using t-BuOK, which is consistent with our previously reported results (ref. 8). See the Supporting Information for the details.

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Further studies showed that t-BuOH derived from the reaction of t-BuOK with H2O may be important in the reactions using t-BuOK as the base. Using KOH as the base, the yield can also be increased to 93% in the presence of 1.0 equivalent t-BuOH (Scheme 1).

Scheme 1