An Improved Synthesis of Urea Derivatives from N-Acylbenzotriazole via Curtius Rearrangement

Vinod Tiwari uses a Curtius rearrangement for an improved synthesis of urea derivatives.

Several molecules incorporating the urea functionality have displayed a vital role in pharmaceutical, analytical, agricultural, polymer science and organic synthesis. This moiety is found in various pharmacologically active molecules, for example carmustine, sorafenib, and many more, thus there is an increasing demand for functionalized ureas to be tested for a variety of applications and biological uses. The search for a versatile protocol for the synthesis of urea derivatives under mild reaction conditions remains though a challenge for synthetic chemists.
Over the last three decades, the benzotriazole group has been considered as one of the most successful synthetic auxiliaries, with N-acylbenzotriazoles to be considered as an alternative to acid chlorides in N-, C-, O- and S-acylations for the synthesis of amides, esters, acid azides, peptides, oxazolines, diketones, and thiazolines. The group of Dr. Vinod Tiwari at Banaras Hindu University (India) previously devised a method for synthesizing carbamates, thiocarbamates, and symmetric ureas from N-acylbenzotriazoles via Curtius rearrangement, yet this method has limitations, particularly for the synthesis of unsymmetrical ureas.

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