Pyrimido[4,5-c]pyridazines. 3. Preferential formation of 8-amino-1H-pyrimido[4,5-c]-1,2-diazepin-6(7H)-ones by cyclizations with .alpha.,.gamma.-dioxo esters
Pyrimido[4,5-c]pyridazines. 3. Preferential formation of 8-amino-1H-pyrimido[4,5-c]-1,2-diazepin-6(7H)-ones by cyclizations with .alpha.,.gamma.-dioxo esters