1. N. D. Heindel and M. C. Chun, Chem. Commun., 664 (1971).
2. It was possible to carry out the reaction in diphenyl ether if the temperature was not allowed to rise above ca 190°; otherwise, an intractable tar resulted.
3. Pyrimidines. XIX. Pyrimido[4,5-e]dihydro-1,3-oxazines and related compounds