Unveiled reactivity of masked diformylmethane with enamines forming resonance-assisted hydrogen bonding leads to di-meta-substituted pyridines.

ABSTRACT

Pyridine, an essential structure in drug development, shows a wide array of bioactivities according to its substitution patterns. Among the bioactive pyridines, meta-substituted pyridines suffer from limited synthetic approaches despite their significance. In this study, we present a condensation-based synthetic method enabling the facile incorporation of biologically relevant functional groups at the meta position of pyridine. This methodology unveiled the concealed reactivity of 3-formyl(aza)indoles as diformylmethane analogs for synthesizing dissymmetric di-meta-substituted pyridines without ortho and para substitutions. Furthermore, we uncovered resonance-assisted hydrogen bonding (RAHB) as the requirement for the in situ generation of enamines, the key intermediates of this transformation. Successful development of the designed methodology linked to wide applications-core remodeling of natural products, drug-natural product conjugation, late-stage functionalization of drug molecules, and synthesis of the regioisomeric CZC24832. Furthermore, we discovered anti-inflammatory agents through the functional evaluation of synthesized bi-heteroaryl analogs, signifying the utility of this methodology.