p-Toluenesulfonic acid monohydrate → Travoprost Impurity 26

Participants

Reaction Steps

p-Toluenesulfonic acid monohydrate (0.20 g, 1.1 mmol) was add to a stirred solution of (8aR,9R,10R,11 aS,Z)-10-((tetrahydro-2H-pyran-2-yl)oxy)-9-((3R,E)-3-((tetrahydro-2H-pyran-2-yl)oxy)-4-(3-(trifluoromethyl)phenoxy)but-1-en-1-yl)-4,5,8,8a,9,10,11,11a-octahydrocyclopenta[b]oxecin-2(3H)-one (14.0 g, 23.0 mmol) in methanol (150 mL). The mixture was stirred for 2 hr at room temperature (TLC monitoring). Then, the reaction mixture was quenched with saturated sodium bicarbonate aqueous solution (200 mL), and the methanol was removed under reduced pressure. The residue was extracted with ethyl acetate (200 mL). The organic layer was separated. The aqueous layer was extracted with ethyl acetate (200 mL). The combined organic layers were dried over magnesium sulfate, filtered and concentrated under reduced pressure to give 15.0 g of the crude product. The crude product was subjected to further purification by flash column chromatography to obtain 8.2 g of the title compound as a solid. DSC analysis showed that the solid contained two crystalline forms (mp 92˜97° C. and mp 113˜118° C.) The solid was recrystallized from a mixture of hexane and ethyl acetate to give 7.3 g of title compound as a single crystalline form (mp 113˜118° C.). The x-ray powder diffraction pattern of crystalline title compound (mp 115˜120° C.) has characteristic peaks expressed in degrees 2θ at approximately 10.7, 12.1, 13.4, 14.5, 14.8, 16.0, 16.6, 17.7, 18.4, 18.5, 19.4, 20.5, 21.0, 22.0, 22.4, 23.3, 24.6, 24.7, 25.1, 28.9, 29.9, 37.9, 44.1.

Provenance & Evidence