ROTUNDIFOLINE, AN OXOINDOLE ALKALOID

In the title compound, methyl 2-{6'-ethyl-2',3',5',6', 7', 8'-hexahydr o-4-hydroxy-2-oxo-spiro[1H-indole-3 (2H), 1'(8a'H)-indolizin]-7'-yl}-3 -methoxyacrylate, C22H28N2O5, the indole molecule is not planar, The p lanarity of the atom group C13-N1-C2-O1 of the indole moiety and the s hort N1-C2 bond of 1.363 (11) Angstrom are due to delocalization of th e benzoid electrons, which extend over the atoms N1, C2 and O1. The fi ve-membered ring of the indolizine moiety is puckered and the six-memb ered ring fused to it has a normal chair conformation. The methoxycarb onyl and the methoxy groups have a trans configuration about the C16=C 17 bond in the acrylate moiety. The structure is stabilized by intramo lecular hydrogen bonding of the type O-H ... N and intermolecular hydr ogen bonding of the type N-H ... O.