Reaction of Organic Halides with Chlorotris-(triphenylphosphine)cobalt(I)

Abstract

Reaction of various types of organic halides with a monovalent cobalt complex, chlorotris(triphenylphosphine)cobalt(I) is described. Reaction of benzylic monohalides, dihalides and trihalides with CoCl(Ph3P)3 gave a coupling product with formation of a carbon-carbon single bond, double bond and triple bond, respectively, under mild and non-basic conditions. Dehalogenation of non-benzylic vicinal dihalides with the reagent took place cleanly to give an olefin in high yield. Reductive coupling of allylic halides using the reagent afforded regioselectively a 1,5-diene with retention of the stereochemistry of the carboncarbon double bond of the allylic halides used. By using this reaction,(E,E,E,E)-squalene was stereospecifically synthesized from (E,E)-farnesyl bromide. Reaction of halohydrins with CoCl(Ph3P)3 gave exclusively a ketone in the presence of an amine or olefin through an alkylcobalt intermediate. A 1,2-hydrogen shift is involved in this reaction. © 1984, The Pharmaceutical Society of Japan. All rights reserved.