4922-04-7Relevant articles and documents
Synthesis of Trinuclear Benzimidazole-Fused Hybrid Scaffolds by Transition Metal-Free Tandem C(sp2)?N Bond Formation under Microwave Irradiation
Dao, Pham Duy Quang,Cho, Chan Sik
, p. 4088 - 4098 (2021/06/16)
2-(2-Bromoaryl)- and 2-(2-bromovinyl)benzimidazoles have been coupled and cyclized with 2-methoxy- and 2-aryloxybenzimidazoles as building blocks in the presence of a base under microwave irradiation to give a class of trinuclear N-fused hybrid scaffolds, benzo[4,5]imidazo[1,2-a]benzo[4,5]imidazo[1,2-c]quinazolines and -pyrimidines, respectively, in good yields. 2-(2-Bromoaryl)- and 2-(2-bromovinyl)imidazoles also reacted with 2-methoxybenzimidazoles in the presence of base under microwave irradiation to give a class of trinuclear N-fused hybrid scaffolds, benzo[4,5]imidazo[1,2-a]imidazo[1,2-c]quinazolines and -pyrimidines, respectively, in similar yields. This process seems to proceed via an initial C(sp2)-N coupling by an addition-elimination nucleophilic aromatic substitution (SNAr) and subsequent cyclization accompanied by extrusion of alcohols.
Exchange, Elimination, and Ring Opening Reactions of 2,3-Dihydrobenzimidazothiadiazoles and 3H-Benzimidazodithiazoles
Martin, Dieter,Tittelbach, Franz
, p. 1007 - 1014 (2007/10/02)
The reactions of benzimidazothiadiazol-3(2H)-ones (1) with isocyanates, isothiocyanates, carbon disulphide, aryl cyanates, acetylenedicarboxylates, and enamines, with exchange of the isocyanate component of (1), to give the corresponding condensed benzimidazole derivatives (1)-(6) are described.Under more severe conditions the 1-benzothiazol-2-yl-1,3-dihydrobenzimidazole-2-thiones (7) were obtained from aromatic isothiocyanates.Thermolysis of the thiadiazoles (1) led to the triazine derivative (12) with elimination of isocyanate and sulphur, and in the presence of phenols to the 2-aryloxybenzimidazoles (13).With amines and CH-acidic compounds, the S,N bond in compound (1) was cleaved to give benzimidazol-2-ylsulphenamides (14), and the ω-substituted methylthiobenzimidazoles (17) and (18).With cyanide ion, insertion into the S,N bond of compound (1) to furnish the thiadiazine (22) took place.The dithiazoles (2) were fragmented by amines to give 1,3-dihydrobenzimidazole-2-thione and guanidine with loss of sulphur; reaction with cyanide ion then gave the dibenzimidazothiadiazine (25).