A novel method for the synthesis of pyrimido[1,2-a]benzimidazoles

5-Amino-3-(diethylamino)-5H-benzo[4,5]imidazo[1,2-b][1,2,4,6]thiatriazine 1,1-Dioxide

“…Treatment of 5 [4] with N,N-diethyl-N -chlorosulfonyl chloroformamidine 1a [2] in N,N -dimethylpropyleneurea (DMPU) in the presence of Hünig's base at room temperature afforded the 5-amino-benzo [4,5]imidazo [1,2-b] [1,2,4,6]thiatriazine derivative (6) as the major product. The crude product, obtained as a precipitate directly from the reaction mixture by simple addition of ethyl acetate and water, was a~7:1 mixture of 6 and an isomeric compound, presumably the 10-amino-benzo [4,5] In the syntheses outlined in Scheme 1, the 2-aminobenzimidazoles 2 acted as 1,3-bisnucleophiles in reactions with the 1,3-bis-electrophilic dichlorides 1 to produce six-membered ring products, the fused thiatriazines 3 (and 4), which are representatives of very rare ring systems.…”

“…During the course of an ongoing research program which produced a cornucopia of new and unusual heterocyclic ring systems from N,N-dialkyl-N -chlorosulfonyl chloroformamidines (1) [2], we established that the regioselective reaction of dichlorides 1 with 2-aminobenzimidazoles (2), in the presence of Hünig's base, afforded benzo [4,5]imidazo [1,2-b] [1,2,4,6]thiatriazine 1,1-dioxides (3) and, on occasion, minor proportions of the isomeric benzo [4,5]imidazo [2,1-c] [1,2,4,6]thiatriazine 2,2-dioxides (4) (Scheme 1) [3].…”

“…During the course of an ongoing research program which produced a cornucopia of new and unusual heterocyclic ring systems from N,N-dialkyl-N′-chlorosulfonyl chloroformamidines (1) [2], we established that the regioselective reaction of dichlorides 1 with 2-aminobenzimidazoles (2), in the presence of Hünig's base, afforded benzo [4,5]imidazo [1,2- In the syntheses outlined in Scheme 1, the 2-aminobenzimidazoles 2 acted as 1,3-bis-nucleophiles in reactions with the 1,3-bis-electrophilic dichlorides 1 to produce six-membered ring products, the fused thiatriazines 3 (and 4), which are representatives of very rare ring systems.…”

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In the quest for discovery of novel bioactive molecules, new heterocyclic ring systems provide templates for exploration of uncharted chemical space. Herein, we describe the synthesis of a new benzo [4,5] ,2,4,6]thiatriazine derivative from readily available 1,2-diaminobenzimidazole and N,N-diethyl-N -chlorosulfonyl chloroformamidine. The product structure, confirmed by X-ray crystallography, bears an exocyclic NH 2 group, which should enable synthesis of an extended range of derivatives of this unusual scaffold.Abstract: In the quest for discovery of novel bioactive molecules, new heterocyclic ring systems provide templates for exploration of uncharted chemical space.

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“…The product structure, confirmed by X-ray crystallography, bears an exocyclic NH 2 group, which should enable synthesis of an extended range of derivatives of this unusual scaffold.Abstract: In the quest for discovery of novel bioactive molecules, new heterocyclic ring systems provide templates for exploration of uncharted chemical space. Herein, we describe the synthesis of a new benzo [4,5]imidazo[1,2-b][1,2,4,6]thiatriazine derivative from readily available 1,2-diaminobenzimidazole and N,N-diethyl-N′-chlorosulfonyl chloroformamidine. The product structure, confirmed by X-ray crystallography, bears an exocyclic NH2 group, which should enable synthesis of an extended range of derivatives of this unusual scaffold.…”