Co-Catalyzed Dual C5/C8-H Bond Functionalization of Imidazo[1,2 -a ]pyrazines with Disulfides and Grignard Reagents.

An efficient difunctionalization at C5/C8 of imidazo[1,2 -a ]pyrazines has been developed using disulfides and Grignard reagents under cheap cobalt catalysis. This one-pot, two-step, three-component transformation is performed under mild conditions; various Grignard reagents (aryl and alkyl) and disulfides are tolerated. Mechanistic studies and control experiments demonstrate this reaction proceeded via an anionic intermediate.