Rhodium(III)-Catalyzed C—C and C—O Coupling of Quinoline N-Oxides with Alkynes: Combination of C—H Activation with O-Atom Transfer

摘要

[Cp*Rh~(III)]-catalyzed C-H activation of arenes assisted by an oxidizing NV-O or N—N directing group has allowed the construction of a number of hetercycles. In contrast, a polar N—O bond is well-known to undergo O-atom transfer (OAT) to alkynes. Despite the liability of N—O bonds in both C-H activation and OAT, these two important areas evolved separately. In this report, [Cp*Rh~(III)] catalysts integrate both areas in an efficient redox-neutral coupling of quinoline N-oxides with alkynes to afford α-(8-quinolyl)acetophenones. In this process the N—O bond acts as both a directing group for C—H activation and as an O-atom donor.