Nitrite → 4,5,6,7-Tetrahydrobenzo[d]thiazol-6-amine

Participants

Reaction Conditions

Reaction Steps

To a solution of 12.8 g (38.9 mmol) 4,5,6,7-tetrahydro-benzothiazole-2,6-diamine dihydrobromide in 220 mL concentrated aqueous hydrochloric acid at −30° C. is drop wise added 66.3 mL of an aqueous 1N solution nitrite over the course of 30 minutes. After further stirring for 1 hour at the same temperature 5.44 ml (52.5 mmol) of a 50% aqueous solution hypophosphoric acid is added. The reaction mixture is stored at 4° C. overnight. After having cooled down the solution again to −30° C. the mixture is slowly basified with 40% aqueous sodium hydroxide solution while temperature is kept at −30° C. The resulting mixture is warmed up to room temperature and extracted with Chloroform/Ethanol 5:1 (3×250 mL). The solution is dried over anhydrous sodium sulfate and concentrated in vacuum. The product obtained is chromatographically purified over silica gel, eluting with dichloromethane/methanol

Provenance & Evidence