Lithium diphenylcopper

Regioselective ring opening of the epoxide in 200 occurs in the presence of bromine and triphenylphosphine to give the bromohydrin 201 (R = Br), which on treatment with azobisisobutyronitrile (AIBN) and tributyltin hydride gives the c o-6-hydroxy-2-azabicyclohexane 201 (R = H) <2001JOC1811>. The 5-substituted derivatives of alcohol 201 (R = Me or Ph) are obtained by treatment of 200 with lithium dimethylcopper or lithium diphenylcopper <20040L1669>. 

Steroid chemists will be interested in the application of lithium dimethylcopper for epoxide opening, to give trans-2-methylcyclohexanols lithium diphenylcopper similarly introduces a phenyl substituent. The reagent is said to be superior to either the Grignard reagent or alkyl-lithium for this purpose, and is selective for epoxides even in the presence of oxo-groups. 

---