Abstract
Single-crystal
X-ray diffraction studies and n.m.r. spectral measurements have now shown structure
of paraensidimerin A, a bisquinolinone
alkaloid from the heartwood of Euxylophora paraensis (Rutaceae),
to be (6aα,7β,15β,16aα)-(�-6,6,9,15,18-pentamethyl-6,6a,7,9,15,16,16a,18-octahydro-7,15-methano-8H,17H-quino[3',4'
:5',6'] pyrano[3',4':5,6] oxocino[3,2-c] quinoline-8,17-dione (8). Paraensidimerin C is a stereoisomer, (6aα,7β,15β,16aβ)-(�)-6,6,9,15,18-pentamethyl-9,15,16,16a,18-octahydro-7,15-methano-8H,17H-quino
[3',4':5',6'] pyrano
[3',4': 5,6] oxocino [3,2-quinoline-8,17-dione (9).
Possible biosynthetic routes to these and other dimeric quinolinone
alkaloids are suggested.