Regioselective synthesis of pyrrolo[2,3-d]pyrimidine derivatives by amine oxide rearrangement

Regioselective synthesis of biologically important pyrrolo[2,3-d]pyrimidine derivatives 4a-h in 75-82% yields are reported. The applied conditions of the less studied rearrangement are the oxidation of 6-N-(4-aryloxybut-2-yn-1-yl)-N-methyl(or ethyl)amino-1,3-dimethyluracils 3a-h with m-chloroperoxybenzoic acid at 0-5 ° C for one hour and then stirring at room temperature for 1012 hours. Compounds 3a-h are prepared by the reaction of 1,3-dimethyl-6-chlorouracil (1) with different (4-aryloxybut-2-yn-1-yl)N-methylamines or (4-aryloxybut-2-yn-1-yl)-N-ethylamines 2 in refluxing ethanol for 12-14 hours.