A New Synthesis of Diaryl Carbodiimides¹

Abstract

Carbodiimides are of considerable importance in synthesis both in the preparation of a variety of urea derivatives and heterocycles, and also as dehydrating agents to cause acylation, particularly in peptide synthesis.² Previous preparations³ of carbodiimides include the elimination of hydrogen sulphide from thioureas, dehydration of ureas, pyrolysis of S-alkylisothioureas, and the catalytic conversion of isocyanates. The thermolysis of tetrazoles,⁴ oxathiadiazoles,⁵ and oxathiadiazole S-oxides⁶ also yields carbodiimides.