From Thioureas, Isothioureas and Selenoureas

The synthesis of carbodiimides by desulfurization of 1,3-disnbstitnted thioureas is the most general method of synthesis because dialkyl-, alkylaryl- anddiarylcarbodiimides with the same or different substituents are obtained. The desnlfurization of N,N -disubstituted thioureas 1 with yellow mercuric oxide is the classical method of synthesis of carbodiimides 2 used by Weith in 1873.  

several N-(tosylmethyl)carbodiimides 4 are prepared similarly from the corresponding thionrea 3.  

In addition to dialkyl-, alkylaryl- and diarylcarbodiimides, heterocyclic carbodiimides, such as l,4-dioxan-2-ylcarbodiimides 6 are obtained by desulfurization of the corresponding thiourea 5.  

This method is also used in the synthesis of and labeled EDC, which is obtained in 57 % yield. Symmetrical and unsymmetrical glycosyl carbodiimides are also obtained in good yields in the desulfurization of the corresponding thioureas with HgO. Bis-Boc-carbodiimide is obtained similarly as an intermediate in the reaction of N,N -di (t-butoxycarbonyl)thiourea with primary amines in the presence of EtsN in DMF.  

A spin labeled carbodiimide derivative 8 is synthesized from the thiourea 7 and HgO.  

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