tert-Butyl carbazate → N'-(2,6-dimethyl-pyridine-4-carbonyl)-hydrazinecarboxylic acid tert-butyl ester

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Reaction Steps

To a solution of 2,6-dimethyl-isonicotinic acid (1.59 g, 10.5 mmol), hydrazinecarboxylic acid tert-butyl ester (1.42 g, 10.7 mmol) and DIPEA (6.06 g, 31.5 mmol) in DMF (33 mL), TBTU (4.05 g, 12.6 mmol) is added. The suspension is stirred at rt for 2 h before it is diluted with EA:diethyl ether 1:1 and washed with 1 N aq. NaOH solution. The washing is extracted three times with DCM, acidified and extracted again with DCM. The combined org. extracts are dried over MgSO4, filtered and concentrated to give crude N′-(2,6-dimethyl-pyridine-4-carbonyl)-hydrazinecarboxylic acid tert-butyl ester (2.79 g) as a brown oil. This material is dissolved 5 M HCl in dioxane (14 mL) and the resulting solution is stirred at rt for 3 h. The solvent is removed in vacuo and the residue is purified by MPLC on RP-C18 silica gel to give 2,6-dimethyl-isonicotinic acid hydrazide hydrochloride (1.71 g) as a beige solid; LC-MS: tR=0.15 min, [M+1]+=166.10.

Provenance & Evidence