A Green Synthesis of 7‐amino‐5‐(4‐aroyl)‐1, 3‐dimethyl‐2, 4‐dioxo‐1, 2, 3, 4, 5, 8‐hexahydropyrido[2, 3‐d]pyrimidine‐6‐carbonitrile Derivatives by a One‐pot Three‐component Reaction. (22nd June 2017)