Pd-Catalyzed Decarboxylation and Dual C(sp3)???H Functionalization Protocols for the Synthesis of 2,4-Diarylpyridines

摘要

The Pd-catalyzed decarboxylation and dual C(sp3)-H bond functionalization approaches have been described for the preparation of symmetrical and unsymmetrical 2,4-diarylpyridines. The developed transformations were realized using nonactivated aromatic ketones and amino acids as C-N sources. The efficacy of the catalyst and reagent combination drives the transformation toward the formation of desired products with high yields and selectivity. The described reaction conditions have seduced the self-reaction of phenylalanine via [2 + 2 + 2] cycloaddition and minimized the formation of 3,5-phenylpyridine as a side product, whereas using glycine as a C-N source, the corresponding 2,6-diarylpyridines were formed as minor products.