Regioselective synthesis of heterocyclic N-sulfonyl amidines from heteroaromatic thioamides and sulfonyl azides

Abstract

N-Sulfonyl amidines bearing 1,2,3-triazole, isoxazole, thiazole and pyridine substituents were successfully prepared for the first time by reactions of primary, secondary and tertiary heterocyclic thioamides with alkyl- and arylsulfonyl azides. For each type of thioamides a reliable procedure to prepare N-sulfonyl amidines in good yields was found. Reactions of 1-aryl-1,2,3-triazole-4-carbothioamides with azides were shown to be accompanied with a Dimroth rearrangement to form 1-unsubstituted 5-arylamino-1,2,3-triazole-4-N-sulfonylcarbimidamides. 2,5-Dithiocarbamoylpyridine reacts with sulfonyl azides to form a pyridine bearing two sulfonyl amidine groups.

Visible Light-Prompted Regioselective Synthesis of Novel 5-Aroyl/hetaroyl-2′,4-dimethyl-2,4′-bithiazoles as DNA- and BSA-Targeting Agents

“…The starting material 2-methylthiazole-4-carbothioamide 6 was prepared by following a reported multistep protocol 35 involving the transformation of an intermediate ethyl generated in situ by the reaction of unsymmetrical 1,3diketones 1 with the mild brominating agent NBS 2 under DCM stirring at room temperature for 30 min. To meet the objective, optimum reaction conditions were required, for which 1-phenylbutane-1,3-dione 1a was selected as the model substrate.…”

“…The starting material 2-methylthiazole-4-carbothioamide 6 was prepared by following a reported multistep protocol 35 involving the transformation of an intermediate ethyl 2methylthiazole-4-carboxylate 5 into thioamide by the reaction with ammonia and P 2 S 5 . The intermediate 5 in turn was achieved by condensing the ethyl bromo pyruvate 4 with methyl thiourea, Scheme 1.…”

“…1,3-Diketones and 2-methylthiazole-4-carbothioamide were prepared according to the literature procedure. NBS was purchased commercially.…”

An efficient metal-free and catalyst-free C–S/C–O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

“…Fascinated by the immense pharmacological profiles of pyrazole, thioamide and amide derivatives, it was envisaged to develop a practical approach towards the synthesis of pyrazolethioamide and pyrazole-amide conjugates. Elemental sulfur was explored as a sulfurating reagent for the generation of thioamides owing to its nontoxic, odorless nature and versatile reactivity profile [65][66][67][68][69][70][71][72][73][74][75][76]. To the best of our knowledge, the syntheses of pyrazole C-3/4/5-linked thioamide and amide conjugates have not been reported.…”