One-pot four-component synthesis of 2-aryl-3,3-dihaloacrylonitriles using potassium hexacyanoferrate(II) as environmentally benign cyanide source

Abstract

Foi descrita uma rota eficiente para reações em uma etapa com quatro componentes incluindo cloretos de aroila, hexacianoferrato(II) de potássio, trifenilfosfina e tetrahaletos de carbono para sintetizar 2-aril-3,3-dicloroacrilonitrilas e 2-aril-3,3-dibromoacrilonitrilas. Este protocolo tem como vantagens o uso de uma fonte não-tóxica de cianeto, alto rendimento e procedimento experimental simples.An efficient route to one-pot four-component reactions of aroyl chlorides, potassium hexacyanoferrate(II), triphenylphosphine and carbon tetrahalides to synthesize 2-aryl-3,3-dichloroacrylonitriles and 2-aryl-3,3-dibromoacrylonitriles was described. This protocol has advantages of use of non-toxic cyanide source, high yield and simple work-up procedure.Keywords: cyanation, four-component synthesis, potassium hexacyanoferrate(II), cyanide source, triphenylphosphine, 2-aryl-3,3-dichloroacrylonitriles, 2-aryl-3,3-dibromoacrylonitriles Introduction 3,3-Dichloroacrylonitriles and 3,3-dibromoacrylonitriles are well-known as the most important synthetic intermediates.1 Although 2-aryl-3,3-dichloroacrylonitriles and 2-aryl-3,3-dibromoacrylonitriles could be prepared directly from phosphorus ylides with aroyl cyanides, 2 the commercially available aroyl cyanides are limited and comparatively expensive. Especially, synthesis of aroyl cyanides had to utilize strong toxic reagents as original cyanide sources, such as HgCN, 3 NaCN, 4 CuCN,5 KCN, 6 and TMSCN, 7 which render the cyanation of aroyl chlorides unsafe and environmentally unfriendly. In addition, the corresponding phosphorus ylides, which are unstable to oxygen and moisture, also required to synthesize by reactions of triphenylphosphine with carbon tetrahalides prior to use. Therefore, there is a need to explore environmentally benign cyanating agents and simple procedure for the synthesis of 2-aryl-3,3-dichloroacrylonitriles and 2-aryl-3,3-dibromoacrylonitriles.Potassium hexacyanoferrate(II), K 4 [Fe(CN) 6 ], is non-toxic and is even used in the food industry for metal precipitation. In addition, it has been described as an antiagglutinating auxiliary for Herein, we wish to report an efficient one-pot fourcomponent synthesis of 2-aryl-3,3-dichloroacrylonitriles and 2-aryl-3,3-dibromoacrylonitriles using potassium hexacyanoferrate(II) as an environmentally benign cyanide source. Results and DiscussionInitially, the reaction of benzoyl chloride, potassium hexacyanoferrate(II), triphenylphosphine and carbon tetrachloride was selected as a model reaction to examine the feasibility of one-pot four-component synthesis of 2-phenyl-3,3-dichloroacrylonitrile under different conditions (Scheme 1). It was found that the optimal mole ratio of benzoyl chloride to potassium hexacyanoferrate(II) and triphenylphosphine was 1:0.2:2 for the reaction, and the excess carbon tetrachloride were required because it acted both as a reactant and a solvent in this reaction. The 0.2 equivalent of potassium hexacyanoferrate(II) used in the reaction indicated that a small excess of CN -was utilized ...

Cyanoaroylation of Imines Bearing a Thiazole Ring using Potassium Hexacyanoferrate(II) as an Eco-Friendly Cyanide Source

“…42 Our current research interests have focused on the cyanation of unsaturated compounds including C=O, C=N and/or C=C functions by nucleophilic addition reactions using K 4 [Fe(CN) 6 ] as an eco-friendly cyanide source. [43][44][45][46][47] As an extension of this research we now report the cyanoaroylation of N-arylidenethiazol-2-amines via a one-pot three-component procedure using K 4 [Fe(CN) 6 ] as a nucleophilic reagent.…”

Eco-Friendly Mono-1,4-Hydrocyanation of Diarenyl Ketones Using Potassium Hexacyanoferrate(II) as a Cyanide Source

“…Recently, K 4 [Fe(CN) 6 ] has been used as a cyanide source for some substitution reactions to synthesise benzonitriles, [11][12][13] aroyl cyanides, 14 benzyl cyanides, 15 and arylsulfonyl cyanides. 16 Our current research focused on the cyanation of unsaturated compounds including C=O, [17][18][19][20] C=N [21][22][23][24][25][26] and/or C=C [27][28][29] by nucleophilic addition reactions using K 4 [Fe(CN) 6 ] as an eco-friendly cyanide source. As an extension of this work, we here report an efficient method for the selective (conjugate) mono-1,4-hydrocyanation of unsaturated compounds bearing one C=O and two C=C bonds, a series of diarenyl ketones, using K 4 [Fe(CN) 6 ] as a selective 1,4-nucleophilic addition reagent and an eco-friendly cyanide source.…”

Conversion of N-Benzyloxycarbonylamino- and N-Tosylamino-Benzyl Phenylsulfones by Green Strecker Reactions to α-Aminobenzyl Nitriles Using Potassium Hexacyanoferrate(II)

“…Recently, K 4 [Fe(CN) 6 ] has been used as a cyanide source for some substitution reactions to synthesise benzonitriles, [11][12][13][14] aroyl cyanides, 15 arylsulfonyl cyanide, 16 benzyl cyanides, 17 and cinnamonitriles. 18 Our research work has focused on the cyanation of unsaturated compounds including C=O, [19][20][21][22] C=N [23][24][25][26] or C=C [27][28] bonds by nucleophilic addition reactions using K 4 [Fe(CN) 6 ] as an eco-friendly cyanide source. Here we report the cyanation of aldimines, generated in situ from N-benzyloxycarbonylamino-and N-tosylamino-benzyl phenylsulfones, to the corresponding N-benzyloxycarbonyl and N-tosyl α-aminobenzyl nitriles by Strecker reactions using potassium hexacyanoferrate(II) as an eco-friendly cyanide source, benzoyl chloride as a promoter, and potassium hydroxide as a base.…”