Dimethyl Sulfoxide → 4-Benzyl 1-(tert-butyl) (R)-2-formylpiperazine-1,4-dicarboxylate

Under nitrogen atmosphere, to a solution of oxalyl chloride (1.64 ml) in dichloromethane (34 ml) under −65° C., was added dropwise a solution of dimethyl sulfoxide (2.0 ml) in dichloromethane (15 ml) and stirred for 10 minutes at the same temperature. A solution of (2S)-2-(hydroxymethyl)piperazine-1,4-dicarboxylic acid 4-benzyl ester 1-tert-butyl ester (3.29 g) in dichloromethane (24 ml) was dropped into the above solution over 5 minutes under −65° C. The reaction mixture was stirred at the same temperature for 15 minutes, then stirred at −45° C. for 90 minutes. Triethylamine (7.85 ml) was added to the solution under −40° C., and the mixture was stirred at 0° C. for 20 minutes. The mixture was poured into saturated aqueous ammonium chloride (100 ml). The organic layer was washed with brine, dried over magnesium sulfate, and evaporated to give (2R)-2-formylpiperazine-1,4-dicarboxylic acid 4-benzyl ester 1-tert-butyl ester (3.33 g) as a colorless syrup.

1. stirringThe reaction mixture was stirred at the same temperature for 15 minutes
2. stirringstirred at −45° C. for 90 minutes
3. stirringthe mixture was stirred at 0° C. for 20 minutes
4. washThe organic layer was washed with brine
5. dry with materialdried over magnesium sulfate
6. customevaporated

ORD-Eintrag

ord-766c0620e8f846868cc5100564247243

Quelldatensatz

uspto-grants-2004_09

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06787543B2