Revision of Structures of Nellionol and Dehydronellionol

Article abstract of DOI:10.1246/bcsj.56.2013

The structures of nellionol and dehydronellionol were revised respectively to 6α,11,12,16-tetrahydroxyabieta-8,11,13-trien-7-one (12) and 6,11,12,16-tetrahydroxyabieta-5,8,11,13-tetraen-7-one (13) by the following syntheses.A mixture of (15R)- and (15S)-12-methoxyabieta-8,11,13-trien-16-ol, prepared from 13-acetyl-12-methoxypodocarpa-8,11,13-triene, was converted into 11,12,16-triacetoxyabieta-8,11,13-trien-7-one (22) via 16-acetoxy-12-benzoyloxyabieta-8,11,13-trien-11-ol.Treatment of 22 with isopropenyl acetate, followed by oxidation with m-chloroperbenzoic acid and subsequent acetylation, afforded 6α,11,12,16-tetraacetoxyabieta-8,11,13-trien-7-one, which was hydrolysed with dilute hydrochloric acid to 12.The ketone 22 was also converted into 13 via 11,12,16-triacetoxyabieta-8,11,13-trien-6-one.The spectral data of 12 and 13 were in good agreement with those of natural nellionol and dehydronellionol.