A simple and highly efficient metal-free method has been developed for hydroxyfluoroalkylation of indoles and imidazo­[1,2-a]­pyridines via TEMPO-mediated C­(sp3)–H and C­(sp2)–H bond cross-dehydrogenative coupling of fluorinated alcohols and indoles. The protocol showed broad substrate scope, afforded good yields of hydroxyfluoroalkylated products, and was amenable for scale-up. Mechanistic investigation indicated involvement of the radical pathway.

Rhodium(III)-catalyzed dehydrogenative annulation of 2-aryl-imidazo[1,2-a]pyridines with maleimides is described. The reaction afforded 1H-benzo[e]pyrido[1',2':1,2]imidazo[4,5-g]isoindole-1,3(2H)-diones in high yields with wide range of functional group tolerance. The reaction proceeds through Rh(III)-catalyzed CÀ H bond activation, followed by maleimide insertion and intramolecular cyclization. Photophysical properties of 1H-benzo[e]pyrido[1',2':1,2]imidazo[4,5-g]isoindole-1,3(2H)-diones were studied with UVvisible and fluorescence spectroscopy and validated by quantum chemical calculations. All the annulated products showed large Stokes shift values with emission in the range of 530-618 nm, and moderate to high quantum yields.

A simple and straightforward approach has been realized for the direct regioselective benzoylation of imidazoheterocycles by oxidative decarboxylation of arylglyoxylic acids in the presence of K2S2O8 as oxidant. Various functional...

Synthesis of 2-amidobenzoic acids has been achieved through TBHP-mediated oxidative ring opening of 2-arylindoles. The synthesized compounds have been evaluated for their antimicrobial activity.

Phenyliodine(III) diacetate -mediated 1,2-ipso-migration of an imidazo[1,2-a]pyridine ring via the formation of an aziridine intermediate in Mannich bases derived from imidazo[1,2-a]pyridines, 2-pyridylamines or arylamines, and formaldehyde is reported. The imidazo[1,2-a]pyridines bearing different substituents showed excellent migratory aptitude and resulted in corresponding N-acetoxymethyl-, N-alkoxymethyl-, and N-hydroxymethyl-N-arylimidazo[1,2-a]pyridine-3-amine derivatives in moderate to excellent (42 examples; 35−93%) yields. Radical trapping experiments confirmed the involvement of a non-radical intermediate. The developed protocol is amenable for a scale-up reaction, and synthetic utility of N-acetoxymethyl products was demonstrated by transforming them to corresponding N-(pyridin-2-yl)imidazo[1,2-a]pyridin-3-amines.