cyclo-L-Ala-L-Glu(OBzl) → 3-((2S,5S)-5-Methyl-3,6-dioxopiperazin-2-yl)propanoic acid

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Reaction Steps

Cyclo-L-Ala-L-Glu(OBzl) (14.5 g, 0.05 mol) was dissolved in 200 ml of trifluorethanol and then 1.5 g of palladium black was added. Hydrogen was bubbled through the suspension and the mixture was stirred for 48 hours. The completion of the reaction was monitored by TLC. After the reaction was complete, the catalyst was filtered off and the solvent was evaporated in vacuum. The residual peptide was dissolved in 200 ml of distilled water and the impurities were extracted with 3×100 ml of EtOAc. The water phase was combined and evaporated in vacuum. The precipitate was washed with ether and hexane and then dried in air. The yield was 10.2 g (94%). Rf=0.2(CHCl3 EtOAc:MeOH:AcOH=6:3:1:0.1); Rf=0.5(CHCl3:EtOAc:MeOH: 32% Ac OH=6:3:1:0.1); HPLC data: retention time 6.7 min.

Provenance & Evidence