(CH3)2CuLi/Cu(OTf)2 Mediated N- or O-Cyclization of Urea-Tethered Cyclobuta[ b]indolines.

A (CH3)2CuLi/Cu(OTf)2 mediated N- or O-cyclization of urea-tethered cyclobuta[ b]indolines has been reported in this paper, giving a new synthetic protocol for the construction of pyrimido[1,6- a]indolone and cyclic imidate derivatives in moderate to good yields with a broad substrate scope under mild conditions. A plausible reaction mechanism has been also proposed on the basis of previous reports and the control experiments.