Imidazo pyridine nitration

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... 

Imtdazo[4,5-c]pyridtne, 4,5,6,7-tetrahydro-synthesis, 5, 623, 640, 641 Imidazo[4,5-c]pyridine-6-carboxylic acid, 4,5,6,7-tetrahydro-synthesis, 5, 623, 641 Imidazopyridines as anthelmintic, 1, 202 synthesis, 5, 462 Imidazo[l,2-n]pyridines deuterium exchange, 5, 611 diazo coupling, 5, 614 Dimroth rearrangement, 5, 613 halogenation, 5, 611 hydrogenation, 5, 614 Mannich reaction, 5, 612 nitration, 5, 612 1-oxides... 

Imidazo[4,5-c]pyridin-4(5H)-ones chlorination, 5, 621 Imidazo[ 1,2-a]pyrimidine, 2-phenyl-nitration, 5, 627... 

While imidazo[4,5-c]pyridine and its 1- and 3-methyl derivatives are resistant to nitration, imidazo[4,5-c]pyridin-2-one and its 1-methyl, 3-methyl, and 1,3-dimethyl derivatives have been readily nitrated at the 4-position (i.e. (152)) <86KGS97>. If the 4- and 6-positions are substituted, as in compound (153), then nitration occurs at the 7-position (e.g. (154)) <87JMC1746>. 

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... 

Nitration of imidazo[4,5-c]pyridin-2(3//)-one and its methyl derivatives (143) to give the 4-nitro compound (144) has been reported (73KGS138, 78MI41005) but not confirmed (80JHC1757). 

An alternative approach to the rationalization of reactivity patterns, involving the three-dimensional visualization of molecular electrostatic potential surfaces, has had some success in explaining the results of the nitration of substituted imidazo[l,2-fl]pyridines <85EJM50l>. 

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