Regioselective Synthesis of 6H-Pyrano[3,2-e]Pyrimidine-2,4-Dione

Abstract: 7-Aryloxymethyl-1,3-dimethyl-6H-pyrano[3,2-e]pyrymidine-2,4-diones (4a-f) were synthesized in 88-92% yields (isolated) by the regioselectively thermal [3s, 3s] sigmatropic rearrangement of 1,3-dimethyl-5-(1-aryloxybut-2-ynyloxy)pyrimidine-2,4-diones, (3a-f) in refluxing chlorobenzene (purified) for 2-4 h.