benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-5-(trimethylsilyl)pent-4-ynoate

benzyl (S)-2-[(tert-butoxycarbonyl)amino]pent-4-ynoate

3,5-bis{[(S)-2,2-dimethyl-3-tert-buthoxycarbonyl-1,3-oxazolidin-4-yl]ethynyl}-4-iodopyridine

benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-5-{bis[2''(S)-(2''',2'''-dimethyl-3'''-(tert-butoxycarbonyl)-4'''-oxazolidin)ethyn-1''-yl]pyridin-3',5'-yl}pent-4-ynoate

4-[4'-(S)-'enzyloxycarbonyl-4'-(tert-butoxycarbonyl)aminobutyl]-1-[5''(S)-benzyloxycarbonyl-5''(tert-butoxycarbonyl)aminopentyl]-3,5-bis[3'''-(S)-(tert-butoxycarbonyl)amino-3'''-carboxypropyl]pyridinium