Trifluoroacetic acid → Cyclo(-Gly-Phe)

Participants

Reaction Steps

To a solution of Boc-glycylphenylalanine ethyl ester (5.96 g) in dichloromethane (20 ml) was added trifluoroacetic acid (20 mL) at room temperature. After stirring 1.5 h, the resulting solution was concentrated in vacuo. The residue was dissolved in water, into which sodium bicarbonate was added until the pH was 9. After the solution was stirred for several hours, the resulting white crystals were collected and dried in vacuo to afford (S)-3-benzyl-2,5-dioxopiperazine (2.29 g, 70% in 2 steps) as a white powder.

Provenance & Evidence