Iridium(III)-Catalyzed Sequential C(2)-Arylation and Intramolecular C-O Bond Formation from Azulenecarboxylic Acids and Diaryliodonium Salts Access to Azulenofuranones.

Described herein is the iridium-catalyzed sequential C(2)-arylation reaction and intramolecular C-O bond formation from azulenecarboxylic acids and diaryliodonium salts, leading to the formation of 3-arylazulenofuranones. The sequential reaction proceeded smoothly through generation of 2-arylazulene-1-carboxylic acids derived from the iridium-catalyzed regioselective C(2)-arylation reaction without the decarboxylation reaction.

Selective C-C bond formation from rhodium-catalyzed C-H activation reaction of 2-arylpyridines with 3-aryl-2H-azirines.

A novel method for the synthesis of acylmethyl-substituted 2-arylpyridine derivatives using 3-aryl-2H-azirines was developed by exploring a prototype reaction using DFT-calculations and carrying out targeted experiments guided by the calculated mechanism. 2H-Azirine was initially hypothesized to ring-open at the metal center to furnish familiar metal nitrene complexes that may undergo C-N coupling. Computational studies quickly revealed and prototype experimental work confirmed that neither the formation of the expected metal nitrene complexes nor the C-N coupling were viable. Instead, azirine ring-opening followed by C-C coupling was found to be much more favorable to give imines that readily underwent hydrolysis in aqueous conditions to form acylmethyl-substituted products. This new method was highly versatile and selective toward a wide range of substrates with high functional group tolerance. The utility of the new method is demonstrated by a convenient one-pot synthesis of biologically relevant heterocycles such as pyridoisoindole and pyridoisoqunolinone.