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Reaction of 2-aminopyridine with allyl bromide, methallyl chloride, 2-bromoallyl bromide, and propargyl bromide in acetone furnished 2-amino-1-allyl-, methallyl-, (2-bromoallyl)-, and propargylpyridinium halides. 2-Amino-1-allyl(methallyl)pyridinium halides reacted with bromine and iodine to form 2-halomethyl-2,3-dihydro-1H-imidazo[1,2-a]pyridinium systems. 2-Amino-1-(2-bromoallyl)pyridinium bromide underwent heterocyclization under the action of bromine, and did not react with iodine. 2-Amino-1-propargylpyridinium bromide reacted with bromine and iodine to form 2-halomemylene-2,3-dihydro-1H-imidazo[1,2-a]pyridinium systems.

2-Iodomethyl-2,3-dihydro[1,3]oxazolo[3,2-a]pyridinium triiodide was synthesized by the reaction of 1-allylpyridin-2(1H)-one with hydrogen iodide in the presence of hydrogen peroxide or with iodine in acetone. The title compound reacted with palladium(II) iodide in DMSO to give crystalline bis(2-iodomethyl-2,3-dihydro[1,3]oxazolo[3,2-a]pyridinium) di-μ2-iodido-tetraiodidodipalladate(II) whose structure was proved by X-ray analysis. The reaction of 2-iodomethyl-2,3-dihydro[1,3]oxazolo[3,2-a]pyridinium triiodide with sodium iodide in acetone afforded 2-iodomethyl-2,3-dihydro[1,3]oxazolo[3,2-a]pyridinium iodide which decomposed into initial 1-allylpyridin-2(1H)-one and iodine on heating in methanol.

The reaction of malononitrile with acetylacetone in alkaline medium afforded a mixture of 2-amino-4,6-dimethylbenzene-1,3-dicarbonitrile and 4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile, whereas only the latter was formed in alcoholic medium in the absence of a catalyst. The alkylation of 4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile with allyl bromide gave a mixture of N- and O-allyl derivatives.

Alkylation of pyridin-2(1H)-one and 5-nitropyridin-2(1H)-one with 4-bromobut-1-ene afforded a mixture of N- and O-butenyl derivatives. 1-(But-3-en-1yl)pyridin-2(1H)-one and 1-(but-3-en-1-yl)-5-nitropyridin- 2(1H)-one reacted with bromine and iodine to give 2-(halomethyl)-3,4-dihydro-2H-pyrido[2,1-b][1,3]-oxazinium halides.

Alkylation of 5-nitro-2-pyridone by alkenyl halides in acetone in the presence of K2СО3 proceeds with generation of a mixture of N- and О-derivatives with N-isomer prevailing. 1-Allyl- and 1-methylallyl-5-nitro-2-pyridone react with halogens with the formation of 2-halomethyl-6-nitro-2,3-dihydrooxazolo[3,2-a]-pyridinium halides. 1-Prenyl-5-nitro-2-pyridone reacts with bromine with the formation of 3-bromine-2,2-dimethyl-7-nitro-3,4-dihydro-2Н-pyrido[2,1-b][1,3]oxazinium bromide, and with iodine giving 2,2-dimethyl-7-nitro-3,4-dihydro-2Н-pyrido[2,1-b][1,3]oxazinium triiodide.