Sodium hydride → 4-Cyclopropylmethyl-3-oxopiperazine-1-carboxylic acid tert-butyl ester

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Reaction Steps

Sodium hydride (60% dispersion in oil) (0.40 g, 10.0 mmol) was added portionwise over 10 min to a solution of 3-oxopiperazine-1-carboxylic acid tert-butyl ester (1.00 g, 5.0 mmol) in N,N-dimethylacetamide (10 ml). The mixture was stirred for 30 min before addition of bromomethylcyclopropane (1.45 ml, 15.0 mmol) and then stirred for a further 18 h. The mixture was diluted with water (100 ml) and extracted with EtOAc (2×100 ml). The combined organic extracts were washed with brine (50 ml), dried over MgSO4 and evaporated to give 4-cyclopropylmethyl-3-oxopiperazine-1-carboxylic acid tert-butyl ester (1.27 g, 100%) as a yellow oil. This oil was dissolved in dichloromethane and hydrogen chloride bubbled through the reaction (2×10 min). The solvent was evaporated to give 1-cyclopropylmethylpiperazin-2-one.HCl (0.95 g, 100%) as a white solid.

Provenance & Evidence