Dicyclohexylcarbodiimide → (S)-1,3-Dibenzylpiperazine-2,5-dione

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Reaction Steps

The title compound was prepared according to the procedure described in Example 2, Step A, except using Boc-L-phenylalanine (12.8 g, 48.2 mmol), ethyl N-benzylglycinate (9.32 g, 48.2 mmol) and dicyclohexylcarbodiimide (96.5 mL 0.5M in dichloromethane, 48.2 mmol). The crude diketopiperazine was triturated with hexane to give the title compound as a white powder (12.5 g). NMR (300 MHz, CD3OD) δ 7.0-7.4 (10H, m), 4.61 (1H, d, J=16 Hz), 4.37 (1H, t, J=5 Hz), 4.24 (1H, d, J=16 Hz), 3.42 (1H, d, J=18 Hz), 3.28 (1H, dd, J=4, 16 Hz), 2.96 (1H, dd, J=6, 16 Hz), 2.55 (1H, d, J=18 Hz).

Provenance & Evidence