Ionic liquid catalyzed Ritter reaction/Pd-catalyzed directed Ortho-arylation; facile access to diverse libraries of biaryl-amides from Aryl-nitriles
Diverse libraries of biaryl-amides bearing N-t-butyl and N-adamantyl groups were synthesized in two steps by the Ritter reaction of aryl-nitriles, using tBuOH and AdaOH as carbocation precursors, and employing [BMIM(SO3H)][OTf] (neat or with [BMIM][PF6] as co-solvent) or tetramethyl guanidinium-ILs [TMG][X] (X = CF3COO, EtOSO3) as dual catalyst/solvent, followed by a Pd-catalyzed directed regioselective ortho[sbnd]C[sbnd]H arylation of the Ritter amides with Ar-X (X = I, Cl). The feasibility to perform the two-steps in sequence is also demonstrated, and potential for recycling/reuse of the ILs is also shown. Preference for [Pd] coordination to the amide carbonyl versus amide nitrogen is borne out by DFT computations.
Digital Object Identifier (DOI)
Sutar, S. M., Savanur, H. M., Kalkhambkar, R. G., Borosky, G. L., Aridoss, G., Laali, K. K. (2020) Ionic Liquid Catalyzed Ritter Reaction/Pd-catalyzed Directed Ortho-arylation; Facile Access to Diverse Libraries of Biaryl-Amides from Aryl-N. Nitriles. (2020) Tetrahedron Letters, 61(50), 152553