Distinct
approaches to synthesize bis-azine biaryls are in demand
as these compounds have multiple applications in the chemical sciences
and are challenging targets for metal-catalyzed cross-coupling reactions.
Most approaches focus on developing new reagents as the formal nucleophilic
coupling partner that can function in metal-catalyzed processes. We
present an alternative approach using pyridine and diazine phosphines
as nucleophilic partners and chloroazines where the heterobiaryl bond
is formed via a tandem SNAr-phosphorus
ligand-coupling sequence. The heteroaryl phosphines are prepared from
chloroazines and are bench-stable solids. A range of bis-azine biaryls
can be formed from abundant chloroazines using this strategy that
would be challenging using traditional approaches. A one-pot cross-electrophile
coupling of two chloroazines is feasible, and we also compared the
phosphorus-mediated strategy with metal-catalyzed coupling reactions
to show advantages and compatibility
