Synthesis of bioactive heterocycles: Sigmatropic rearrangements of 1,3-dimethyl-6-[methyl(4-aryloxybut-2-ynyl)amino]pyrimidine-2,4(1H,3H)-diones

Article abstract of DOI:10.1055/s-2001-16097

A number of 1,3-dimethyl-6-[methyl (4-aryloxybut-2-ynyl)amino]pyrimidine-2,4(1H,3H)-diones 4a-i were synthesised in 69 to 80% yields by the reaction of 6-chloro-1,3-dimethyluracil (6-chloro-1,3-dimethylpyrimidine-2,4(1H, 3H)-diones) and 1-aryloxy-4-N-methylaminobut-2-yne in refluxing ethanol for 12 hours. The tertiary amines 4a-i were then heated in refluxing 1,2-dichlorobenzene for 17 hours to give 5-[(E)-aryloxymethylidene]-1,3,8-trimethyl-5,6,7,8-tetrahydropyrido[2,3-d] pyrimidine-2,4(1H,3H)- diones 5a-i in 55 to 75% yields.