Quinazolines. XI. Synthesis of 2,4-diamino-5, 10-diliydrobenzo[g] quinazolines

An unequivocal synthesis of 2,4-diamino-5,10-dihydrobenzo[g]quinazolines is described, starting from methyl 2-tetralone-3-carboxylates. Condensation with guanidine yielded 2-amino-4-hydroxy derivatives, which were thiated with phosphorus pentasulfide and S-alkylated with dimethyl sulfate. The resultant 2-amino-4-methylthio compounds were converted into 2,4-diamino derivatives by amination at elevated temperature and pressure. Attempted synthesis from 3-cyano-1,4-dihydro-2-methoxynaphthalene and guanidine was unsuccessful.