From A. obscurinervium bark extract there was isolated (+)-aspidocarpine (la), (+)-aspidolimine (lb), a new alkaloid of the methoxyindole type, and four new alkaloids (dihydroobscurinervine, Ila; obscurinervine, lib; dihydroobscurinervidine, lie; and obscurinervidine, lid) representative of a new class of heptacyclic indole alkaloids. The structures were assigned on the basis of analysis, infrared, ultraviolet, n.m.r., and mass spectra of the parent alkaloids and of a variety of chemical transformation products. Dihydroobscurinervidinol (IIIu) and dihydroobscurinervinol (IIIt) were synthesized from depropionylaspidoalbine (IVb) by addition of iodopropanol and iodobutanol, respectively, followed by cyclization of the more polar isomer of each addition pair through its monobrosylate, and lithium aluminum hydride reduction of the ether linkage. Neblinine, an alkaloid isolated from A. neblinae Monachino, could be shown to be 15-demethoxyobscurinervidine (lie). Dihydroneblininane (IIIz) and its C-22 epimer were synthesized from deacetylaspidocarpine (Ic) and the configuration of the natural isomer at position 22 established by n.m.r. measurements. The configuration at position 4 in the original series of alkaloids II-IIg was assigned by three independent and mutually consistent n.m.r. comparisons. © 1964, American Chemical Society. All rights reserved.