Facile conversion of primary thioamides into nitriles with butyltin oxides

Recent developments in dehydration of primary amides to nitriles

“…Nitriles are naturally found in various bacteria, fungi, plants and animals and are extensively applied as raw materials for the production of a variety of pharmaceuticals, agrochemicals, Various methods 13,14 have been developed for the syntheses of nitriles using different synthetic strategies including the addition reaction of multiple bonds (I), 15 oxidation of amines (II), 16 reduction of nitroalkanes (II), 17 reactions of alcohols (II), 18 dehydration or rearrangement of oximes (III) and amidoximes (IV), 19 dehydration of amides or water shuffling with amides (V), 20 dehydrosulfurization of thioamides (V), 21 substitution of aryl and alkyl-halides/azides (VI), 22 and reaction of aldehydes (VI) 23 (Scheme 1). The classical methods viz., nucleophilic substitution of alkyl halides, the Sandmeyer reaction of diazotized aniline, the Rosenmund-von Braun reaction of aryl halides, etc., have limited applications due to the usage of highly toxic cyanide sources.…”

Synthesis of Nitriles <i>via</i> the Iodine-Mediated Dehydrosulfurization of Thioamides

“…11) Furthermore, alternative methods for the synthesis of aryl nitriles that do not require cyanide sources have been reported, for example, the dehydration of amides 12,13) or aldoximes, 14) the oxidative coupling of alcohols with ammonia, 15) the conversion of carboxylic acids to nitriles, 16) and the dehydrosulfurization of thioamides. The last of these examples is a particularly efficient approach, and involves the treatment of thioamides with diverse desulfurizing agents such as the transition metal reagents MnO 2 , 17) AgOAc, 18,19) Hg(OAc) 2 , 18) and Cu(OAc) 2 , 18) heavier main group reagents such as nBu 2 SnO, 20,21) diphosphorus tetraiodide, 22) telluroxide, 23) and tellurinic acid anhydride, 24,25) a combination of Zn(OTf) 2 13) or In(OTf) 3 26) with N-methyl-N-(trimethylsilyl) trifluoroacetamide, a combination of sulfur with sodium nitrite, 27) and other reagents such as benzotriazol-1-yloxytris(pyrrolidinol) phosphonium hexafluorophosphate, 28) 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 29) and formamide chlorides. 30) Moreover, an efficient method for the conversion of thioamides to nitriles using the organobismuth reagent, triphenylbismuth dichloride, 31) or gold nanoparticles 32) has been recently reported by Doris and colleagues, respectively.…”

Triphenylbismuth Dichloride‐Mediated Conversion of Thioamides to Nitriles

“…In addition, nitriles can also be prepared by functional group inter‐conversion such as the dehydration of amides or aldoximes, oxidative coupling of alcohols with ammonia, conversion of carboxylic acid to nitriles and dehydrosulfurization of thioamides. In the latter transformation, harsh conditions, strong oxidants, toxic reagents, expensive noble metals, complex systems, or extended reaction times are often involved. With these features in mind, and as part of our longstanding interest in organobismuth chemistry and synthetic methods, we report herein the straightforward conversion of variously substituted aromatic and aliphatic thioamides 1 to the corresponding nitriles 2 using a pentavalent bismuth reagent (Ph 3 BiCl 2 ) in combination with a mild base (NEt 3 ) (Scheme ).…”