(2R,5R,11bS,1'S)-2-(tert-butoxycarbonyl)amino-5-(1'-methoxycarbonyl-2'-phenylethyl)carbamoyl-3-oxo-2,3,5,6,11,11b-hexahydro-1H-indolizino[8,7-b]indole

(R)-2-[((2R,5R,11bS)-2-Benzyloxycarbonylamino-3-oxo-2,3,5,6,11,11b-hexahydro-1H-indolizino[8,7-b]indole-5-carbonyl)-amino]-3-phenyl-propionic acid methyl ester

(2R,5R,11bS)-2-(benzyloxycarbonyl)amino-5-carboxy-3-oxo-2,3,5,6,11,11b-hexahydro-1H-indolizino[8,7-b]indole

(2R,,5R,11bS)-2-(tert-butoxycarbonyl)amino-5-carboxy-3-oxo-2,3,5,6,11,11b-hexahydro-1H-indolizino[8,7-b]indole

(2R,5R,11bS)-2-(benzyloxycarbonyl)amino-5-methoxycarbonyl-3-oxo-2,3,5,6,11,11b-hexahydro-1H-indolizino[8,7-b]indole