Synthesis of fused 3-trifluoromethyl-1,2,4-triazoles via base-promoted [3 + 2] cycloaddition of nitrile imines and 1H-benzo[d]imidazole-2-thiols

Abstract

Here we report a strategy for the facile assembly of fused 3-trifluoromethyl-1,2,4-triazoles in moderate to excellent yields through triethylamine-promoted intermolecular [3+2] cycloaddition pathway, employing nitrile imines and 1H-benzo[d]imidazole-2-thiol as the...

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

“…Enol ethers, 1,4-naphthoquinones, o-trimethylsilylphenyl triflate and chalcones have all been reacted with fluorinated nitrile imines to give a series of fluoroalkylated pyrazoles by Jasiński's team [67][68][69][70][71][72] (Scheme 11a). Moreover, the trifluoromethylated 1,2,4-triazoles were synthesized with excellent regioselectivities in [3 + 2] cycloaddition reactions of trifluoromethylated hydrazonoyl chlorides with imidates, amidine and 1H-benzo[d]imidazole-2-thiols, all of which were individually reported by Wang, Deng and Cai, respectively [77][78][79] (Scheme 12a). Meanwhile, the Jasiński Scheme 11: Substrate scope for [3 + 2] cycloadditions with trifluoroacetonitrile imines reported by Jasiński's team and other groups.…”

(3+2)-Cycloadditions of Levoglucosenone (LGO) with Fluorinated Nitrile Imines Derived from Trifluoroacetonitrile: An Experimental and Computational Study

“…In addition, diverse thioketones (aromatic, ferrocenyl, and cycloaliphatic) react as typical 'superdipolarophiles' [2] with nitryl imines 1, yielding highly substituted analogues of heterocycles 5 in a regioselective manner [15,16] Electron deficient fluorinated thioamides and fluorinated nitroalkenes also react regioselectively, with 1 yielding highly fluorinated 2-trifluoromethyl-1,3-dihydro-1,3,4-thiadiazole and 3-trifluoromethyl-5-fluoropyrazole derivatives, respectively [17,18]. In a very recent publication, the synthesis of fused 3-trifluoromethyl-1,2,4-triazoles by means of a multi-step reaction of nitrile imines 1 with enolizable 2,3-dihydro-benzoimidazole-2-thiones was reported [19].…”

“…-7.20 (m, 2CHarom); 7.30-7.34 (m, 2CHarom);13 C NMR: δ 51.6, 63.2, 71.1, 100.4, 68.5, 114.4, 121.9, 129.2, 120.8 (q, 1 JC,F = 268.1 Hz, CF3); 134.8 (q, 2 JC,F = 37.3 Hz, C-CF3); 142.9, 194.6 (C=O) 19. F NMR (CDCl3): δ -64.0; IR: ν 1744s (C=O), 1600s, 1494s, 1312s, 1297m, 1259s, 1185s, 1092vs, 976s, 913s, 799s, 752s, cm−1 ; EA for C14H11F3N2O3 (326.28): calcd.…”