O-(Benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate → HCID 178526864, compound

Participants

Reaction Steps

4-Morpholin-4-ylmethyl-benzene-1,2-diamine (1 mol. eq.) and 4-nitro-1H-pyrazole-3-carboxylic acid (1 mol. eq.) were dissolved in dimethylformamide (DMF) (10 vol.). O-(Benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate (TBTU) (1.2 mol. eq.) was added and the mixture was stirred at ambient temperature for 24 hours. The mixture was concentrated in vacuo until no further solvent was seen to distil. The residue was then dissolved in glacial acetic acid (10 vol.) and heated at 65° C. for ˜12 hours. The mixture was concentrated in vacuo and then dissolved in water (6 vol.) at 75° C. The black solution was cooled to 0-5° C. over 2 hours during which time a solid was formed. The solid was removed by filtration and the aqueous filtrate was diluted with ethyl acetate (4 vol.) and tetrahydrofuran (2 vol.). Solid NaHCO3 was added slowly to the stirred mixture until no further effervescence was observed and a pH of 6.8 was reached. The mixture was then stirred until a precipitation was observed. After standing the mixture at 0-5° C. for 2 hours, the solid was collected by filtration and washed with water (2 vol.) and ethyl acetate (2 vol.) and dried to give 5-morpholin-4-ylmethyl-2-(4-nitro-1H-pyrazol-3-yl)1H-benzimidazole as a brown solid (40%). (LC/MS (basic method): Rt 1.93, [M−H+]− 327).

Provenance & Evidence