Methyl iodide → (+/-)-Methyl N,N'-dibenzyloxycarbonylpiperazine-2-carboxylate

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Reaction Steps

To a flask containing N,N'-dibenzyloxycarbonylpiperazine-2-carboxylic acid (Step 1, 12.83 g, 32.20 mmol) dissolved in dry DMF (50 mL) is added methyl iodide (5.6 mL, 90.00 mmol) and potassium carbonate (4.60 g, 32.20 mmol). The mixture is stirred for 4 hours at ambient temperature under an inert atmosphere. The reaction is concentrated in vacuo, diluted with ethyl acetate (150 mL), washed with water (3×50 mL) and saline, dried over MgSO4, concentrated in vacuo, and chromatographed on silica gel (70-230 mesh), eluting with hexane/ethyl acetate (50/50). The appropriate fractions are combined (Rf =0.55, TLC, hexane/ethyl acetate, 50/50) and concentrated in vacuo to give the title compound, NMR (CDCl3) 7.31, 5.15, 5.12, 4.70, 4.1-2.9.

Provenance & Evidence