Jan. 1978 A Synthesis of 6,il-Dihydro-2-methyl-6#-pyrimido[2,l-fe]qumazolin-4-ones Ii. Friary- Research Division, Schering-Plough Corporation, Bloomfield, New Jersey 07003 Received November 14,1977 Reductive cyclization of 2-methylthio-l-(2-nitrobenzyl)-6-pyrimidones with stannous chloride and acetic acid in methanol gives 6,ll-dihydro-6//-pyrirnido[2,l-ò]quiruizolin -4-ones, and, with trialkylphosphites, 6,ll-dihydro-ll-alkylpyrimido[2,l-6 ]quinazolin-4-ones. ...