326 nm, in chloroform. The substance is sensitive to ultraviolet light at wavelengths shorter than 320 nm. Synthesis Its synthesis starts by reacting 1-aminomorpholine with formaldehyde and hydrogen cyanide to give 2. Nitrosation gives the N-nitroso analog (3) which cyclizes to the sydnone (4) on treatment with anhydrous acid. Formation of the ethyl urethane is then made possible by reacting linsidomine with ethyl chloroformate. History The substance was first synthesised at Takeda in 1970. Its antihypertensive and vasodilating properties were discovered the same year. References Vasodilators 4-Morpholinyl compunds Carbamates Oxadiazoles