Triphenylphosphine → (R)-tert-Butyl 3-(4-amino-3-iodo-1H-pyrazolo[3,4-d]pyrimidin-1-yl)piperidine-1-carboxylate

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Reaction Steps

To a stirred mixture of 3-iodo-1H-pyrazolo[3,4-d]pyrimidin-4-amine (5.9 g, 22.6 mmol, 1.00 equiv), (S)-tert-butyl 3-hydroxypiperidine-1-carboxylate (10 g, 50 mmol, 2.2 equiv) and triphenylphosphine (11.8 g, 45 mmol, 2.0 equiv) in tetrahydrofuran (300 mL) at 10° C. was added a solution of diisopropyl azodicarboxylate in tetrahydrofuran (30 mL) dropwise in 30 min. The resulting mixture was stirred at room temperature for 12 h and then concentrated under vacuum. The residue was purified on a silica gel column eluted with dichloromethane/methanol (100/1) to give 3 g (33%) of (R)-tert-butyl 3-(4-amino-3-iodo-1H-pyrazolo[3,4-d]pyrimidin-1-yl)piperidine-1-carboxylate as a yellow solid.

Provenance & Evidence