3-(5-Fluoropyrimidin-4-yl)-2-[(1R)-1-(4-methoxyphenyl)ethyl]-3-methyl-6-(1-tetrahydropyran-2-ylpyrazol-4-yl)isoindolin-1-one → 3-(5-Fluoropyrimidin-4-yl)-3-methyl-6-(1H-pyrazol-4-yl)isoindolin-1-one

Dissolve 3-(5-fluoropyrimidin-4-yl)-2-[(1R)-1-(4-methoxyphenyl)ethyl]-3-methyl-6-(1-tetrahydropyran-2-ylpyrazol-4-yl)isoindolin-1-one (65 g, 123 mmol) in trifluoroacetic acid (600 mL) and heat to 75-80° C. for 16 hours. Evaporate under reduced pressure and dilute with ethyl acetate (500 mL) and water (500 mL). Adjust the pH of the aqueous layer to 8-9 with aqueous 6 N NaOH, extract the aqueous layer with ethyl acetate (3×500 mL), combine the organic layers, wash with saturated aqueous sodium chloride, dry with sodium sulfate, filter, and evaporate under reduced pressure. Chromatograph the crude product on silica gel with 50-100% ethyl acetate/petroleum ether. Combine the product fractions and evaporate under reduced pressure to give a yellow foam (33 g, 87% crude). Repeat the reaction conditions with 3-(5-fluoropyrimidin-4-yl)-2-[(1R)-1-(4-methoxyphenyl)ethyl]-3-methyl-6-(1-tetrahydropyran-2-ylpyrazol-4-yl)isoindolin-1-one and combine the products (10 g, 18.9 mmol). Dissolve the combined products in methanol and stir with SiliaBond® Thiol (Silia MetS® Thiol) at 15-20° C. for 20 hours, filter, and evaporate under reduced pressure to give the title compound with 77% ee (38 g, 87%).