A Novel One-pot Synthesis of Isothiocyanates and Cyanamides from Dithiocarbamate Salts Using Environmentally Benign Reagent Tetrapropylammonium Tribromide

Abstract

A highly efficient and simple protocol for the synthesis of isothiocyanates and cyanamides from their respective amines in the presence of a mild, efficient, and non-toxic reagent tetrapropylammonium tribromide is described. High environmental acceptability of the reagents, cost effectiveness and high yields are the important attributes of this methodology.

Dithiocarbamate-mediated thioamidation of arylglyoxylic acids by decarboxylative–decarbonylative C–C bond formation reactions

“…To understand the mechanism, we have performed a set of control experiments. Initially we considered elemental sulfur which might be generated by the decomposition of dithiocarbamate in the presence of an oxidizing agent 24 as the key sulfurizing agent in the thioamidation reaction and the reaction proceeds through Takemoto's type mechanism 19 a (Scheme 3a) via imine formation between the secondary amine and phenylglyoxylic acid followed by nucleophilic attack by the elemental sulfur-based nucleophile. However, the reaction between piperidine and phenylglyoxylic acid in the presence of 4 equivalents of elemental sulfur produced the desired thioamide product ( 3a ) only in a trace amount along with the formation of benzil under identical reaction conditions (Scheme 4a).…”

Recent advancement in the synthesis of isothiocyanates

“…Numerous methods using CS 2 have been reported to overcome these limitations. 55–75 Several methods have been explored to broaden the substrate scope of electron-deficient anilines and aminopyridines. 55,57–61,67,71,72,74,75 Moreover, employing a strong base, 69 ball milling, 56 a photoredox catalyst, 72 an electrolytic reaction, 73 or an appropriate desulfurization reagent 60,61,68,71 enables the one-step synthesis of isothiocyanates.…”

“…55–75 Several methods have been explored to broaden the substrate scope of electron-deficient anilines and aminopyridines. 55,57–61,67,71,72,74,75 Moreover, employing a strong base, 69 ball milling, 56 a photoredox catalyst, 72 an electrolytic reaction, 73 or an appropriate desulfurization reagent 60,61,68,71 enables the one-step synthesis of isothiocyanates. Table 1 provides a comprehensive review of the progress in dithiocarbamate salt protocols over the past decade.…”

Recent Advancement in Synthesis of Isothiocyanates

“…Several methods have been explored to broaden the substrate scope of electron-deficient anilines and aminopyridines. [55,[57][58][59][60][61]67,71,72,74,75] Moreover, employing a strong base [69] , ball milling [56] , a photoredox catalyst [72] , an electrolytic reaction [73] , or an appropriate desulfurylating reagent [60,61,68,71] enables the one-step synthesis of isothiocyanates.…”