Carbamate → 3-[5-fluoro-1-(2-fluoro-phenyl)-1H-indazol-3-yloxymethyl]-piperidine-1-carboxylic acid tert-butyl ester

Participants

Reaction Steps

3-[5-fluoro-1-(2-fluoro-phenyl)-1H-indazol-3-yloxymethyl]-piperidine-1-carboxylic acid tert-butyl ester was prepared according to the procedure for Intermediate 57 from Intermediate 23 (0.500 g, 2.03 mmol) and (R)-3-methanesulfonyloxymethyl-piperidine-1-carboxylic acid tert-butyl ester (0.655 g, 2.23 mmol). A room temperature stirred solution of carbamate in EtOAc (5.43 ml) was treated with 5.30 ml of a 4.0 M HCl solution in dioxane. The reaction was allowed to stir overnight at room temperature and was concentrated under reduced pressure, triturated with EtOAc and again concentrated under reduced pressure. This process was repeated three times. Recrystallization of the foam was attempted from hexanes/EtOAc and acetone/hexanes without success. The free base was formed by adding Dowex 550A (OH) Anion Exchange Resin to a stirred solution of the salt in MeOH (10 ml). The mixture was stirred for 30 minutes, filtered and the beads washed three times with 20 of methanol. The organic phase was concentrated under reduced pressure to yield 0.3628 g of the free base as a yellow oil. To a stirred solution of the oil in EtOAc (10 ml) was added maleic acid (0.111 g, 1.0 equivalents). A solid precipitated out and the mixture was concentrated under reduced pressure. The solid was triturated with hexanes/Et2O, filtered and washed with Et2O. The white solid was dried in the oven under reduced pressure at 80° C. overnight to yield 0.390 g (69.6%) of the title maleate salt.

Provenance & Evidence