Chemical interactions between 2-mercaptobenzazoles and ?-acceptors

Novel Reaction Products from Thiobarbituric Acid of Biological Interest

“…Hydrogen proton transfer from the cation radical to DDQ anion radical generates 23 and 24. The presence of semiquinone 24 induces the dehydrogenation of 25, which is followed by dimerization to give the intermediate 27 after split off sulphur [37,48,51] (identified experimentally). The latter abstracts a molecule of hydrogen from 1 and eliminates another from H 2 O to give 5-chloro-6-hydroxy-4-oxo-1,4-dihydrobenzo [4,5]furo [2,3-…”

“…Continuation of our studies on the reactions of 2-dicyanomethyleneindane-1,3-dione (15) with compounds containing active methylene groups such as N-arylisoindolines [45], arylaminomethylbenzimidazole-2-thiols [46], thioxopyrimidine derivatives [40], benzimidazolylacetonitrile [47], and 2-mercaptobenzazoles [48] prompted us to investigate the behavior of 2-dicyanomethyleneindane-1,3-dione (15) and its facile isomer 2,3-dicyano-1,4-naphthoquinone [49,50] The 1 H-NMR spectrum of 19 displayed two broad singlets at 11.80 and 12.15 ppm due to pyrimidine-NH's, in addition to the aromatic protons. In its 13 C-NMR spectrum, C-6 and C-5 resonate at δ 166.44 and 105.00 respectively; further peaks at δ 143.20, 149.90 (Ar-C-OH), 167.34 (C = O) and 182.50 (C = S) were also observed.…”

Current methods for the synthesis of 2-substituted azoles

“…246 Mourad et al have investigated the reaction of a variety of 2-amino-1,3-azoles with activated quinones, giving products such as 274 in good yields (Scheme 124). 247,248 Imidazo[1,2-b]thiazolines 249 undergo nucleophilic displacement with allylic and benzylic Grignard reagents (Scheme 125); alkyl Grignard and alkyl or aryl lithium reagents result in nucleophilic attack on sulfur and loss of ethylene to furnish 2-thioalkyl-1H-imidazoles. The authors note the relief of ring strain via loss of ethylene to be a driving force in the latter cases.…”

1,4‐Dioxo‐1,4‐dihydronaphthalene‐2,3‐dicarbonitrile and 1,1,2,2‐Tetracyanoethene in Heterocyclization

“…Mixing of 2‐mercaptobenzimidazole ( 15 ) with twofold molar amount of DCNQ 1 leads to a CT complex, which is in equilibrium with the two components, and thereafter the reaction products 16 and DCNQ‐H 2 ( 17 , Scheme ) were obtained . However, reaction of 15 with TCNE 2 afforded 1‐amino[1,3]thiazepino[3,2‐ a ]benzimidazole‐2,3,4‐tricarbonitrile ( 18 ), and 2‐(benzimidazol‐2‐yl)‐2‐(benzimidazol‐2‐ylthio)cyanoacetamide ( 19 ) and dibenzimidazol‐2‐yl sulfide ( 20 ) were isolated (Scheme ) .…”