Hypervalent iodine(III) promoted synthesis of isothiocyanates in water

Abstract

General. Amines, CS2, DIB, Et3N, Pyridine, KOH, and NaOH were purchased from Aldrich and used without further purification. The solvents were purchased and dried according to standard procedure prior to use. 1 1 H NMR (400 MHz) spectra were recorded with a Varian 400 spectrometer. Infrared (IR) spectra recorded on a Perkin Elmer Spectrum one FT-IR spectrometer.General Procedure for Aryl/Alkyl isothiocyanate: In a 10 mL round bottom flask containing a magnetic stir bar, Amine (1.0 equivalent), NaOH (1.5 equivalent) and TPGS-750-M/H2O (1wt%, 0.4 mL, 1.0 M) were sequentially added. The reaction mixture was stirred at room temperature for 2h. After starting material was completely consumed, as monitored by TLC, DIB (1.5 equivalent) and NaOH (1.5 equivalents) were sequentially added and stirring continued for 60 minutes. Then ethyl acetate (2 x 1mL) was added to the reaction mixture, which was stirred for 5 minutes. The organic layer was transferred using a Pasteur pipet and evaporated under reduced pressure to give the crude product. The residue was purified by column chromatography over silica gel by using 100% hexane as eluent to obtain isothiocyanate derivative .

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.…”