Stereochemistry in trivalent nitrogen compounds. 42. N-(Arylthio)benzimidazoles. Torsional barriers and 1,3 rearrangement

The chemistry of sulfenamides

“…40 The reaction of nitrobenzenesulfenyl chlorides with imidazoles alone or in the presence of 1 equiv of triethylamine yields exclusively disulfides (eq 4).41 However, benzimidazoles react in the usual manner with 2,4-dinitrobenzenesulfenyl chloride in the presence of triethylamine to produce sulfenamides (eq 5). 16,17 R and/or R1 = N02 RJ = H, Et, i-Pr. CH3 R5 = H, N02, CH3…”

Chlorotropy of 1-Chlorobenzimidazole

“…This mechanism would be a stepwise process, in contrast to the concerted mechanism proposed in Scheme . Other examples of intermolecular mechanisms for tautomeric equilibria, other than prototropy, have been reported: thiatropy in 1-(arylthio)benzimidazoles, acylotropy in 3,5-dimethyl- N -phenyl-1 H -pyrazole-1-carboxamide, and methyltropy in 2-methylmercaptobenzothiazole. All of these examples occurred by different intermolecular mechanisms …”

Selective synthesis of novel biimidazole derivatives, bis-biimidazole and tri-biimidazole

“…Biim, 15 2-(chloromethyl)benzimidazole 17 Imidazole (0.20 g, 3.00 mmol) and NaH (0.14 g, 6.00 mmol) in dry THF (10 ml) were stirred at room temperature for 3 h and then warmed to boiling. The BPB (0.51 g, 2.00 mmol) in THF (10 ml) was added dropwise over 12 h. The resulting mixture was concentrated under reduced pressure.…”