Transition-metal-free synthesis of bipyridines from pyridyl pyrimidylsulfones

Abstract

We report a transition-metal-free cross-coupling of readily accessible pyridyl pyrimidylsulfones with azaaryl Grignard reagents that provides direct access to diverse bis-azaaryl products, including 2,2′-, 2,3′-, and 2,4′-bipyridines, under mild conditions, while also accommodating related azaaryl–heteroaryl products. The reaction proceeds through S_NAr activation of the pyrimidylsulfone to generate magnesium pyridyl sulfinates in situ, followed by desulfinative C–C bond formation. The synthetic utility of the method is demonstrated by regiodivergent access to bipyridines and the preparation of caerulomycin F.