Cuprates as Selective Metalating Reagents for Aromatic Halides

Regioselective reactions with almost no decrease in enantiomeric purity: the 5-exo (2) and 6-endo (3) cyclization products are formed from epoxide 1 on reaction with [Li3ZnMe3(SCN)2] and [Li3Cu(CN)Me3], respectively. No further reagents are needed. Halogen – metal exchange of 1 with the appropriate ate complex and subsequent intramolecular epoxide opening by the arylcuprate moiety results in the asymmetric synthesis of 2 and 3, potential precursors of the antibiotics CC-1065 and duocarmycin.