Isopropanol → HCID 57440226, compound

Participants

Reaction Conditions

Reaction Steps

A 2000 ml reactor equipped with mechanical stirrer, thermometer and condenser are loaded with 100 g of (S)-2-acetylamino-4,5,6,7-tetrahydro-benzothiazole-6-carboxylic acid [(I), R=—NH—CO—CH3] of 97% enantiomeric purity, suspended in 700 ml of isopropanol; 84.16 g of triethylamine are added. The mixture is refluxed (about 80° C.) and a solution consisting of 120.42 g of diphenylphosphoryl azide (DPPA) is dropped therein in 2 hours. After 2 hours, the reaction mixture is cooled to 20-30° C. and added with 500 ml of water and 1.6 g of sodium hydroxide. Isopropanol is distilled off under vacuum, then 400 ml of ethyl acetate are added. The mixture is refluxed for 15 minutes, then the hot suspension is filtered through Celite. The solution is cooled to 20-30° C. and added with of 1800 ml of water. The phases are separated and the organic phase concentrated to dryness. The residue is taken up with 200 ml of acetonitrile. The suspension is heated at 50° C. for 1 hour, then cooled to 20° C. and filtered to obtain 75 g of isopropyl (S)-(2-acetylamino-4,5,6,7-tetrahydro-benzothiazol-6-yl)-carbamate, with 97% enantiomeric purity.

Provenance & Evidence