Synthesis of 2-amino-6,7,8,9-tetrahydro-6-phenethyl-3H-pyrimido[4,5-e][1,4]diazepin-4(5H)-one: a model for a potential pyrimido[4,5-e][1,4]diazepine-based folate anti-tumor agent

Reductive cyclization of 2-{N-[(2-amino-4,6-dichloropyrimidin-5-yl)methyl]-N-phenethylamino}acetonitrile (5) with Raney nickel and hydrogen gave the chloropyrimido[4,5-e][1,4]diazepine 3 which could not be converted to 2 via an attempted nucleophilic aromatic substitution with hydroxide. The title compound (2) was prepared, however, by the reductive cyclization of 2-{N-[(2-amino-4-chloro-6-methoxypyrimidin-5-yl)methyl]-N-phenethylamino}acetonitrile (13) followed by treatment with trimethyliodosilane.