DMSO as a Dual Carbon Synthon and Water as Oxygen Donor for the Construction of 1,3,5-Oxadiazines from Amidines.

A selective and efficient synthesis of diaryl 1,3,5-oxadiazines was established for the first time from simple and readily available amidines in wet DMSO. DMSO was employed as a dual carbon synthon and water offered the oxygen atom to construct the oxadiazine ring. The reaction involved two new C-N and two new C-O bond formations.