3-ethyl-1,13-dioxo-3a,4,4a,11,13,13a-hexahydro-1H,3H-furo[3',4':6,7]indolizino[1,2-b]quinoline-3-carboxylic acid amide

4'-ethyl-1',4',7',8'-tetrahydro-4'-hydroxy-3'H,10'H-spiro[1,3-dioxolane-2,6'-pyrano[3,4-f]indolizine]-3',10'-dione

[1-(2-methoxycarbonyl-2,3-dihydro-1H-pyrrolo[3,4-b]quinolin-3-ylmethyl)-2-oxo-butyl]-malonic acid dimethyl ester

(8-ethoxycarbonyl-9-oxo-9,11-dihydro-indolizino[1,2-b]quinolin-7-yl)-malonic acid di-tert-butyl ester

4-ethyl-6-formyl-1,5b,6,11,11a,12-hexahydro-4H-pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14-dione