Imidazo pyridines bromination

Imidazo[l,2-n]pyridine, 2-(2-furyl)-bromination, 5, 611 Imidazo[l,2-n]pyridine, 3-hydroxy-synthesis, 5, 631... 

Imidazo[4,5-6]pyridine, 3-(2,3-0-isopropylidene-5-p-toluenesulfonyl-jS-D-ribofuranosyl)-intramolecular alkylation, 5, 616 Imidazo[4,5-6]pyridine, 1-methyl-bromination, 5, 617 nitration, 5, 617... 

A kinetic study of the bromination of imidazo[l,2-u]pyridine showed reaction to take place on the neutral species, at the 3-position, and 2000 times faster than at the 5-position in imidazole (74AJC2349), the formation of a stable 6ir-pyridinoid ring in the transition state for the former accounting for this reactivity difference. 

Nitration or bromination of 1- or 3-methylimidazo[4,5-fc]pyridines (102) occurs at C-6 giving (101) (68KGS953, 71KGS279), but nitration of imidazo[4,5-fe]pyridine 4-oxide (104) takes place at C-7 to give (105) (66UC403), indicating the effect of the iV-oxide on the... 

Among other condensed thiazole ring systems, imidazo[2,l-6]thiazoles (tetramisole is a member of this class), thiazolo-pyrimidines, and thiazolo-pyridines continue to attract the most interest. Attention is concentrated on synthesis and biological activity. Unexpectedly, dihydrothiazolo[3,2-a]pyridinium bromide is readily brominated when the pyridine ring has a 3-nitro-substituent but not when it has a 3-amino-substituent. 

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