A process for preparing a pharmaceutical calcipotriol treatment of psoriasis

The present invention discloses a method for preparing a medicament treating psoriasis calcipotriol, comprising the steps of: (1) (5E, 7E, 22E, 24S) -24- cyclopropyl-1,3-bis [[( 1,1-dimethyl) tert-butyl-silyl] oxy] - 9,10-secocholesta-5,7,10 opening (19), 22-tetraene-ene-24-ol in a suitable solvent and anthracene, in configuration conversion takes place under UV irradiation, to yield intermediate compound: (2) an intermediate compound in the presence of a deprotecting agent, deprotected to give calcipotriol. The method is simple, high yield, suitable for industrial production.