Process for preparing R-(+)-3-morpholino-4-(3- tert-butylamino-2-hydroxypropoxy)-1,2,5-thiadiazole

The present invention provides a process for preparing optically active timolol. The process comprises the following steps. Firstly, reacting 3-hydroxy-4-morpholino-1,2,5-thiadiazole with an optically active epichlorohydrin in the presence of a solvent system, which has a first volume and a catalyst optionally in the presence of a suitable base to obtain an optically active intermediate product. Secondly, treating the optically active intermediate product with a solution, which has a second volume and comprises tert-butylamine to obtain an optically active timolol. The solvent system used in the first step can be an amide solvent, sulfoxide solvent, cyclic hydrocarbon solvent, ketone solvent, or a heterocyclic solvent. The catalyst used in the first step can be an alkali metal hydroxide, alkali metal carbonate, alkali metal hydrogen carbonate, piperidine, pyridine, triethylamine, potassium hydroxide, sodium hydroxide, potassium carbonate, and other heterocyclic bases.