Intramolecular H-bonding interaction in angular 3-π-EWG substituted imidazo[1,2-a]pyridines contributes to conformational preference

Table 1 H-5 chemical shift of some imidazo[1,2-a]pyridines substituted with angular EWG at position 3

Name	δ H-5^aExp	δ H-5^a	Reference
imidazo[1,2-a]pyridine	8.05	8.05	[8]
3-nitroso-2-phenyl imidazo[1,2-a]pyridine	9.89	9.97-10	[10]
3-formyl-2-phenyl imidazo[1,2-a]pyridine	9.68	9.66	[11]
3-formyl imidazo[1,2-a]pyridine		9.52	[12]
3-benzoyl imidazo[1,2-a]pyridine	9.75	9.75	[13]
3-acetyl-2-methyl imidazo[1,2-a]pyridine	9.58	9.81	[14]
3-(2-chloroacetyl) imidazo[1,2-a]pyridine	9.48	9.48	[13]
3-nitro imidazo[1,2-a]pyridine	9.38	9.40	[5]
3-nitro-2-(4-nitrophenyl) imidazo[1,2-a]pyridine	9.50^b	9.95^c	[15]

^a HNMR taken in CDCl₃ unless otherwise stated. ^b Solvent DMSO-d6. ^c Solvent TFAA.

ISSN: 2661-801X