An efficient method is described for the synthesis of 2-substituted quinolino[7’,8’:5,6]pyrano[2,3-d] pyri-midin-4(3H)-ones(6) via a tandem aza-Wittig annulation process. The iminophosphorane(3) reacted with aromatic isocyanates, followed by heterocyclization on the addition of secondary amines, phenols or alcohols to give the corresponding guanidine intermediates(5), which were cyclized in the presence of a catalytic amount of a base to tetra-cyclic compounds 6 in good yields. The corresponding carbodiimide(4) and guanidine-type intermediate compounds 5 need not be isolated. An efficient method is described for the synthesis of 2-substituted quinolino [7 ’, 8’: 5,6] pyrano [2,3- d] pyri-midin-4 (3H) Wittig annulation process. The iminophosphorane (3) reacted with aromatic isocyanates, followed by heterocyclization on the addition of secondary amines, phenols or alcohols to give the corresponding guanidine intermediates (5), which were cyclized in the presence of a catalytic amount of a base to tetra-cyclic compounds 6 in good yields. The corresponding carbodiimide (4) and guanidine-type intermediate compounds 5 need not be isolated.