4-(2-Azidoethoxy)-3-oxo-butanoic Acid 2-Cyanoethyl Ester is an intermediate in the synthesis of 3-O-Desethyl-5-O-desmethyl Amlodipine (D291305). 3-O-Desethyl-5-O-desmethyl Amlodipine is an impurity of Amlodipine (A633495), which is a dihydropyridine calcium channel blocker.