8-ethyl-8-methoxy-2,3,5,8-tetrahydro-1H-6-oxa-3a-aza-cyclopenta[b]naphthalene-4,7-dione

2-(6-hydroxy-5-oxo-1,2,3,5-tetrahydro-indolizin-7-yl)-2-methoxybutyric acid methyl ester

8-ethyl-1-hydroxy-8-methoxy-2,3,5,8-tetrahydro-1H-6-oxa-3a-aza-cyclopenta[b]naphthalene-4,7-dione

2-methoxy-2-(5-oxo-6-trifluoromethanesulfonyloxy-1,2,3,5-tetrahydro-indolizin-7-yl)-butyric acid methyl ester

8-ethyl-8-methoxy-2,3,5,8-tetrahydro-1H-6-oxa-3a-aza-cyclopenta[b]naphthalene-1,4,7-trione