2-Aminothiophenol → Benzo(d)thiazol-2-amine

Participants

Reaction Steps

NaOH (6.35 ml; 20 N) was added at RT to a solution of 2-aminobenzenethiol (0.0637 mol) in dimethylsulfoxide (115 ml). The mixture was stirred at RT for 30 minutes. (±)-β-[4[[bis(methylthio)methylene]amino]phenyl]-N,N,α-trimethyl-1H-imidazol-1-ethanamine (0.0637 mol), prepared according to intermediate (19a), was added. The mixture was stirred at 110° C. overnight, then poured out on ice, extracted with EtOAc and washed with HCl (3 N). The aqueous layer was basified with a concentrated NH4OH solution and extracted with EtOAc. The organic layer was separated, dried, filtered and the solvent was evaporated. The residue was separated by column chromatography over silica gel (eluent: CH2Cl2/CH3OH/NH4OH 97/3/0.1 and 90/10/0.1). Two pure fractions (F1 and F2) were collected and their solvents were evaporate F1 was crystallized from 2-propanone. The precipitate was filtered off and dried. The residue was taken up in K2CO3 (10%), filtered and the solvent was evaporated, yielding 1.12 g (5%) (±)-(A)-N-[4-[2-dimethylamino)-1-(1H-imidazol-1-yl)propyl]phenyl]-2-benzothiazolamine (comp. 1). F2 was crystallized from 2-propanone. The precipitate was filtered off and dried. The residue was recrystallized from 2-propanone. The precipitate was filtered off and dried, yielding 0.9 g (4%) of (±)-(B)-N-[4-[2-dimethylamino)-1H-imidazol-1-yl)propyl]phenyl]-2-benzothiazolamine (comp. 2).

Provenance & Evidence