A Mild Method for the Synthesis of Carbamate-Protected Guanidines Using the Burgess Reagent

Abstract

A simple method for the synthesis of carbamate-protected guanidines from primary amines is described. A variety of thioureas derived from primary amines and isothiocyanates react with the Burgess reagent to give the corresponding guanidines via either a stepwise or one-pot procedure. By tuning the carbamoyl units of isothiocyanates and the Burgess reagent, differentially N,N'-diprotected guanidines can be obtained. Selective deprotection of the products affords N-monoprotected guanidines.

Crystal structure of 3-(2-bromophenyl)-1,1-dimethylthiourea, C9H11BrN2S

“…Therefore, the synthesis of such compounds is of general interest. The most common procedures for the synthesis of substituted thioureas involve reactions of amines with carbon disul de in the presence of sodium or potassium hydroxide [6][7][8], of aliphatic amines with isocyanides in the presence of elemental sulfur [9] and of primary amines with isothiocyanates [10]. Thioureas can be used as precursors for the production of heterocycles, e.g.…”

Crystal structure of 3-(4-chlorophenyl)-1,1-dimethylthiourea, C9H11ClN2S

“…Thioureas can be synthesized using various procedures and have been used as intermediates in organic syntheses [5][6][7][8][9][10][11].…”

1-(2-Bromo-4-methylphenyl)-3,3-dimethylthiourea

“…Thioureas show various biological activities (Yao et al, 2012;Kocyigit-Kaymakcioglu et al, 2013;Korkmaz et al, 2015;Yang et al, 2015;Tahir et al, 2015;Shakeel et al, 2016) and therefore their syntheses are always of interest (Kong et al, 2015;Nguyen et al, 2014;Maki et al, 2014;Chau et al 2014;Maddani & Prabhu, 2010). The X-ray crystal structures of some 1-(2-bromophenyl)-3,3-dimethylthiourea derivatives have been published recently (El-Hiti et al, 2014, 2017: as part of our ongoing studies in this area, we now describe the synthesis and structure of the title compound.…”