The Absolute Configuration of the Spermine Alkaloid Aphelandrine

Article abstract of DOI:10.1002/hlca.19860690508

The relative configuration of aphelandrine (1) was established by X-ray structure determination.The absolute configuration of the centers 11 and 18 was determined earlier by chiroptic measurements.Therefore, structure 1 with the configurations 11S, 17S, and 18S represents the absolute configuration of aphelandrine.In the presence of base, 1 was converted to (11S, 17R, 18R)-orantine (2).The 1H-NMR coupling constants between H-C(17) and H-C(18) (part of the dihydrofuran ring) are very much dependent on the substituent pattern of the amino N-atoms N(6) and N(10).