New synthetic reactions catalyzed by cobalt complexes*
Hideki Yorimitsu and Koichiro Oshima
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku, 615-8510 Kyoto, Japan
Abstract: Without suffering from β-elimination, cobalt complexes allow cross-coupling reactions of alkyl halides with Grignard reagents. A combination of a cobalt complex and trimethylsilylmethyl Grignard reagent effects Mizoroki-Heck-type reaction of alkyl halide with styrene, which conventional palladium catalysts have never made possible. Cobalt exhibits intriguing catalytic activities on hydrophosphination and allylzincation of alkynes. Silylmethylcobalt reagent is a powerful tool for the synthesis of highly silylated ethenes.
Keywords: cobalt; synthesis; Grignard reagents; cross-coupling reactions; Mizoroki-Heck reactions.
*Pure Appl. Chem. 78, 197-523. An issue of reviews and research papers based on lectures presented at the 13th IUPAC International Symposium on Organometallic Chemistry Directed Towards Organic Synthesis (OMCOS-13), Geneva, Switzerland, 17-21 July 2005.