tert-butyl 1'-(8-(benzyloxycarbonyl)-8-azabicyclo[3.2.1]octan-3-yl)-1H-spiro[isoquinoline-4,4'-piperidine]-2(3H)-carboxylate → (R)-tetrahydrofuran-3-yl 3-(2-(dimethylcarbamoyl)-2,3-dihydro-1H-spiro[isoquinoline-4,4'-piperidine]-1'-yl)-8-azabicyclo[3.2.1]octane-8-carboxylate

Participants

Reaction Steps

tert-Butyl 1′-(8-(benzyloxycarbonyl)-8-azabicyclo[3.2.1]octan-3-yl)-1H -spiro[isoquinoline-4,4′-piperidine]-2(3H)-carboxylate 4b (2.700 g, 4.638 mmol) was dissolved in methanol (30 mL) and treated with 10% wet Pd/C (2.7 g) and NH4COOH (5.844 g, 92.756 mmol). The mixture was allowed to stir vigorously overnight under an empty balloon (for venting). LC/MS analysis shows complete conversion to the desired product. The reaction mixture was filtered through a pad of Celite under a nitrogen atmosphere, and the filter cake was rinsed with methanol (4×30 mL). The filtrate was concentrated to provide the crude product, which was taken up in a mixture of EtOAc (100 mL) and NaHCO3 sat (100 mL). Some product stays undissolved in both layers. The biphasic mixture was filtered, and the precipitate was washed with H2O (20 mL) and vacuum dried overnight to provide 1.01 g pure tert-butyl 1′-(8-azabicyclo[3.2.1]octan-3-yl)-1H-spiro[isoquinoline-4,4′-piperidine]-2(3H)-carboxylate 4c. The filtrate layers were separated, and the aqueous layer was extracted with Et2O (100 mL) and CH2Cl2 (2×100 mL). The combined organic layers were dried on Na2SO4 and concentrated to provide additional product 4c (600 mg). LC/MS m/z [M+H]+ 412.4, retention time 2.16 min (10-99% CH3CN—H2O gradient, with 0.05% TFA, 5 min).

Provenance & Evidence