Abstract
16-Dehydrogitoxigenin 3-acetates (VIII and IX) were newly synthesized, their optical rotation, absorption spectra, coloration reaction, and isomerization phenomena were compared with those of gitoxigenone (III and IV), and these acetates were found to have characteristics in common originating in the carbonyl at 16-position and unsaturated lactone ring at 17-position. These two isomeric acetates (VIII and IX) were reduced with sodium borohydride to form 16- and 17-epimers (VII, X, XI, and XII) of gitoxigen 3-acetate by which the mode of isomerization of the 16-dehydro compound from (VIII) to (IX) was clarified. This has given experimental basis for Cardwell's theory that Jacobs' α-oxoisodigitoxigenone is 17β-3, 16-dehydrogitoxigenin (III) and that β-oxoisodigitoxigenone is 17α-3, 16-dehydrogitoxigenin (IV).
[Correction] Journal of the Pharmaceutical Society of Nippon Vol.82 No.8 (1962) pp.e2b-e3
