Synthesis and Halocyclization of 5-Allyl-2-benzyl(allyl)sulfanyl-6-methylpyrimidin-4(3H)-ones

Alkylation of 5-allyl-6-methyl-2-thiouracil with benzyl chloride and allyl bromide afforded 2-benzyl(allyl)sulfanyl-5-allyl-6-methylpyrimidin-4(3H)-ones. 5-Allyl-2-(benzylsmfanyl)-6-methylpyrirmdin-4(3H)-one reacted with molecular bromine and iodine to give substituted furo[2,3-d]pyrimidines. Depending on the conditions, the reaction of 5-allyl-2-(allylsulfanyl)-6-methylpyrimidin-4(3H)-one with iodine led to the formation of 6-allyl-3-(iodomethyl)-5-methyl-7-oxo-2,3,7,8-tetrahydro[1,3]thiazolo[3,2-a]pyrimidinium iodide or 3,7-bis(iodomethyl)-5-methyl-2,3,6,7-tetrahydrofuro[2,3-d][1,3]thiazolo[3,2-a]pyrimidinium iodide.