Sodium Hydroxide → Benzyl 4-[2-(tert-butoxycarbonyl)hydrazinyl]piperidine-1-carboxylate

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Reaction Steps

To a solution of benzyl 4-oxopiperidine-1-carboxylate (4.08 g, 17.5 mmol) in 50 mL of methanol was added tert-butylcarbazate (2.31 g, 17.5 mmol). The mixture was stirred at room temperature for 3 h and then was concentrated in vacuo to afford a white foam. This residue was taken up in 50 mL of 50% glacial acetic acid. To the resulting suspension was added sodium cyanoborohydride (1.1 g, 17.5 mmol) portionwise with vigorous stirring at room temperature. After the addition was complete the mixture was stirred for 3 h at room temperature. The mixture was neutralized with 1N NaOH/solid NaOH and then extracted twice with methylene chloride. The combined organics were washed with sat'd aq sodium bicarbonate and brine, dried (Na2SO4), filtered through a pad of silica gel and concentrated in vacuo to afford Example 12A, benzyl 4-(2-(tert-butoxycarbonyl)hydrazinyl)piperidine-1-carboxylate, as a solid (6.0 g) which was pure enough to be used without purification. LRMS (ESI): 350.1 (M+H)+.

Provenance & Evidence