(3S,3'S,8a'R)-5'-oxo-1-tosyl-2',3',6',7',8',8a'-hexahydro-5'H-spiro[indoline-3,1'-indolizine]-3'-carboxylic acid

(6S,12bR)-4-oxo-1,2,3,4,6,7,12,12b-octahydropyrido[2,1-a]β-carboline-6-carbaldehyde

(6S,12bR)-12-(tert-butoxycarbonyl)-1,2,3,4,6,7,12,12b-octahydro-4-oxoindolo[2,3-a]quinolizine-6-carboxylic acid

(12bR)-tert-butyl-1,2,3,4,6,7-hexahydro-4-oxoindolo[2,3-a]quinolizine-12(12bH)-carboxylate