p. 1345 - 1348
(2007/10/03)1-tert-butoxycarbonyl-2(S)-n-butyl-4-(2,3-dimethylbenzoyl)piperazine
4-Benzyl-1-tert-butoxycarbonyl-2(S)-n-butylpiperazine
1-Benzyl-3(S)-n-butylpiperazine-2,5-dione
(S)-1-Benzyl-3-butyl-piperazine
1-tert-butoxycarbonyl-2(S)-n-butylpiperazine