p-Toluenesulfonic acid monohydrate → Bimatoprost

Participants

Reaction Steps

p-Toluenesulfonic acid monohydrate (0.03 g, 0.17 mmol) was added to a stirred solution of (5Z)-N-ethyl-7-((1R,2R,3R,5S)-5-hydroxy-2-((S,E)-5-phenyl-3-(tetrahydro-2H-pyran-2-yloxy)pent-1-enyl)-3-(tetrahydro-2H-pyran-2-yloxy)cyclopentyl)hept-5-enamide (2.0 g, 3.4 mmol) in methanol (20 mL). The mixture was stirred for 2 hours at room temperature. Then, the reaction mixture was washed with saturated aqueous solution of sodium bicarbonate (50 mL). The layers were separated and the aqueous layer was extracted with ethyl acetate (20 mL). The organic layers were dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was crystallized from hexane and ethyl acetate to give Bimatoprost in a white crystalline form (77.5% yield). UPLC (ACQUITY UPLC BEH C18) analysis of the crude product showed that no 5,6-trans isomer, 15β-isomer or any other isomers were found.

Provenance & Evidence