1,3,3-trimethylpiperazine-2,5-dione

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Piperidine (867 mL) was added to N-[(α,α-dimethyl-(9H-fluoren-9-ylmethoxy)carbamino] acetylsarcosine ethyl ester (743 mg) in N,N-dimethylformamide (20 mL), followed by stirring at room temperature for 1 hour. N,N-Dimethylformamide (60 mL) was added thereto. The resultant mixture was stirred at 80° C. for 14 hours, and cooled in air. The reaction solvent was evaporated under reduced pressure, and the residue was dissolved in ethyl acetate, and then to the resultant solution, hexane was added. The precipitated crystals were recovered by filtration, to thereby give the title compound (162 mg, 59%). cooled in air The reaction solvent was evaporated under reduced pressure the residue was dissolved in ethyl acetate to the resultant solution, hexane was added The precipitated crystals were recovered by filtration