A Mild and Efficient Synthesis of Symmetrical Diaryl Carbodiimides

Abstract

Carbodiimides are useful intermediates in organic synthesis both in the preparation of a variety of urea derivatives and also as dehydrating agents to cause acylation in peptide synthesis. Previous synthetically useful preparations of carbodiimides include the elimination of hydrogen sulphide from thioureas by use of butyllithium² or 2-chloro-1-methylpyridinium cation³; dehydration of ureas with the reagent triphenylphosphine/carbon tetrachloride⁴; and pyrolysis of 2,4,6-tri-phenylpyridine imidoyl-N-imines^.5