p. 693 - 696
(2007/10/02)1-(((9H-fluoren-9-yl)methoxy)carbonyl)-4-(tert-butoxycarbonyl)piperazine-2-carboxylic acid
4-(tert-butoxycarbonyl)-1-(methylsulfonyl)piperazine-2-carboxylic acid
piperazine-1,3-dicarboxylic acid 1-(4-nitrobenzyl)ester
(R)-piperazine-1,2,4-tricarboxylic acid 1,4-di-tert-butyl ester
2-hydroxymethylpiperazine