Octahydro[1,4:5,8]dimethanoanthraquinone as a Cheap and Readily Avail­able Electron-Transfer Oxidant for Biaryl Synthesis from Organocuprates

The preparation of biaryls via oxidation of organocuprates with easily synthesized octahydro[1,4:5,8]dimethano­anthraquinone (DAQ) is described. The oxidative coupling of organocuprates using DAQ was successfully employed for the preparation of highly hindered biaryls and 9- and 10-membered macrocycles containing biaryl linkages. The oxidative reactivity of DAQ towards organocuprates is found to be similar to the commonly utilized quinones such as duroquinone (DQ) and tetra-tert-butylbiphenoquinone (BQ) and is in accord with their similar reduction potentials (measured by an electrochemical method). The structures of the quinones are also established with the aid of X-ray crystallography. The usage of DAQ for biaryl synthesis is advocated owing to the ready separation of reduced DAQ-H2 from biaryls as well as its ready-availability in multi-gram quantities.