tert-butyl 4-((5-bromo-1-isopropyl-1H-pyrazol-4-yl)methyl)-4-isocyanatopiperidine-1-carboxylate → Tert-butyl tetrahydrospiro[piperidine-4,5'-pyrazolo[3,4-c]pyridine]-1-carboxylate

Participants

Reaction Steps

To a mixture of tert-butyl 4-((5-bromo-1-isopropyl-1H-pyrazol-4-yl)methyl)-4-isocyanatopiperidine-1-carboxylate (1.4 g, 3.3 mmol) in 2-methyl tetrahydrofuran (10 mL) was added t-butyl lithium (1.7 M in hexane, 4.3 mL, 7.2 mmol) at −78° C., under argon. After the addition was complete the mixture was allowed to warm to room temperature and was stirred for 18 hours. The mixture was quenched with water (10 mL) and then diluted with ethyl acetate (20 mL). The layers were separated and the organic layer was washed with brine (10 mL), dried over sodium sulfate, filtered and the solvent removed in vacuo. The crude product was purified by flash column chromatography to give tert-butyl tetrahydrospiro[piperidine-4,5′-pyrazolo[3,4-c]pyridine]-1-carboxylate (0.77 g, 67%). +ESI (M+H) 374.1; 1H NMR (300 MHz, CDCl3, δ): 7.34 (s, 1H), 6.35 (s, 1H), 5.45 (m, 1H), 3.57 (m, 2H), 3.42 (m, 2H), 2.79 (s, 2H), 1.70 (m, 4H), 1.45 (m, 15H).

Provenance & Evidence