Cobalt induced Csingle bondH bond activation and C8-arylation of caffeine with aryl bromides

The 8-caffeinyl cobalt(І) complex (C8-caffeinyl)Co(PMe3)4 (1) was obtained by reaction of caffeine with cobalt(I) complex CoMe(PMe3)4 via Csingle bondH bond activation with the escape of methane. The reaction of 1 with arylbromide afforded cobalt(II) complex (C8-caffeinyl)Co(PMe3)3Br (2) and the C,C-coupling products 8-aryl caffeine (3 and 4), 8-phenyl caffeine and 8-(2′-pyridinayl)caffeine. The crystal structures of complexes 1 and 2 were determined by X-ray diffraction.