Reaction of diphenylcyclopropenethione with a variety of N-substituted pyridinium imines in refluxing benzene gives 2, 4, 5-trisubstituted-6 H-1, 3-oxazin-6-thiones in good to excellent yields. The structure of 2, 4, 5-triphenyl-6 H-1, 3-oxazin-6-thione prepared in this manner was proven by oxidation and by hydrolysis to the known 2, 4, 5-triphenyl-6 H-1, 3-oxazin-6- one. In the preparation of 4, 5-diphenyl-2-ethoxy-6 H-1, 3-oxazin-6-thione changing the ...
