Simple Mixed Tricyclohexylphosphane–Triarylphosphite Complexes as Extremely High-Activity Catalysts for the Suzuki Coupling of Aryl Chlorides

✍ Scribed by Robin B. Bedford; Catherine S. J. Cazin; Samantha L. Hazelwood (néeWelch)

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 70 KB
• Volume: 114
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/1521-3757(20021104)114:21<4294::aid-ange4294>3.0.co;2-g

✦ Synopsis

The coupling of aryl halides with aryl boronic acids, the Suzuki reaction (Scheme 1), is one of the most powerful and versatile methods for the synthesis of biaryls. There has recently been considerable interest in the development of new catalysts that can couple aryl chlorides because of the lower cost and greater availability of these substrates compared with their bromide or iodide counterparts. Unfortunately the comparatively high CÀCl bond strength makes aryl chlorides difficult to activate. Consequently most catalysts that are able to catalyze aryl chloride coupling reactions still need to be used in relatively high loadings. Therefore the advantages associated with the use of aryl chlorides may be negated by the high cost of the catalyst systems.

We recently reported that complex 1, based on the comparatively inexpensive ligands N,N-dimethylbenzylamine and tricyclohexylphosphane, shows very high activities in Suzuki coupling reactions of aryl chlorides at low catalyst loadings. [2c] Previously we had shown that the orthopalladated NMe