Activated nitriles in heterocyclic synthesis : synthesis of new [1]benzoopyrano[3,'4':5,6]pyrano[2,3-d]pyrimidine and [1]benzopyrano[3',4':5,6]pyrano[3,2-e][1,2,4]triazolo[1,5-c]-pyrimidine derivatives with promising antibacterial activity - Abd El-Wahab, Ashraf H. F. (Array, 2002)