2- Methylimidazo pyridine, reaction with

In reaction [46] with equimolar amount or twice the amount of N-bromosuccinimide (NBS) 2-(l-adamantyl)-7- methylimidazo[l,2-a]pyridine (52), obtained from 2-amino-4-methylpyridine and bromomethyl 1-adamantyl ketone, is converted into 2-(l-adamantyl)-3-bromo-7-methylimidazo[l,2-a]pyridine (55). In reaction with three times the amount of N-bromosuccinimide in the presence of trace quantities of water 2-(l-adamantyl)-3-bromo-7-formylimidazo-[l,2-fl]pyridine (54 ) is formed. They suppose that compound 54 is the product from hydrolysis of 2-(l-adamantyl)-3-bromo-7-dibromomethylimidazo[l,2-a]pyridine (b) formed dming the reaction [46]. 

Several 3-aryl-2-methylimidazo[4,5-b]pyridines (36 X = H, R = H, 4-F, 4-Et X = Cl, R = H, 4-F, 3-CF3, 2,4-Me2, 2,4-Ch, 2-Me-6-Et, 3-CF3-4-C1) with pesticidal activity have been prepared in moderate yields by the reaction of /V-(2-chloro-3-pyridyl)acetamides (37) with aromatic amines in the presence of P2O5 and Et3N-HCl at 150 C.140 With X = H the cyclized products were isolated directly, whereas with X = Cl treatment of the intermediate amidines (38) with K2CO3 in DMF was required to arrive at the final cyclized product. 

Halogenation of the imidazo[4,5-6]pyridine 4-oxides has provided some interesting results. Treatment of compound (123 R = H) with phosphorus oxychloride gave, with loss of the /v-oxide group, a mixture of the 5-chloro (124) and 7-chloro (125) isomers in comparable amounts in an overall 74% yield (Equation 3) <82JHC513>. The reaction of 3-methylimidazo[4,5-6]pyridine 4-oxide (123 R = CH3) with phosphorus oxychloride also gave a mixture of products but the yields were different, i.e. 5-chloro (124) (20%) and 7-chloro (125) (41%). However, with l-methylimidazo[4,5-6]pyridine 4-oxide (126), the chlorine atom was introduced exclusively into the more sterically hindered 7 position to give the 7-isomer (127). None of the 5-isomer was detected in this reaction (Equation (4)). 

Reaction of l-methylimidazo[4,5-c]pyridine-2(3Jf )-thlone (177) with nitric acid, or that of l-methylimidazo[4,5-c]pyridine and its 2-methyl derivative with a mixture of nitrous... 

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