Studies toward the total synthesis of diterpenes in the labdane series. III. Synthesis of two epimeric 6, 7, 8-trihydroxylabdadienes

• Published in: Tetrahedron Vol. 50; no. 7; pp. 2055 - 2070
• Main Authors: Herlem, Denyse, Khuong-Huu, Françoise, Kende, Andrew S.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 14.02.1994; Elsevier
• Subjects: Alicyclic compounds, terpenoids, prostaglandins, steroids; Chemistry; Exact sciences and technology; Organic chemistry; Preparations and properties; Terpenoids; Acetal; Epimer; Saturated compound; Bicyclic compound; Conjugated dienic compound; Diterpene; Aldehyde
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/S0040-4020(01)85068-7

The syntheses of 6β,7β, 8α, and 6β, 7β, 8β-trihydroxy labdadienes, 2a and 2b respectively, were performed starting from the decalin 3, in order to determine the exact structure of compounds, isolated from plant sources, for which configuration at C-8 was not clearly demonstrated. As a result, the structure 2a was established with certainty for crotomachlin, a diterpine from Croton macrostachys. The syntheses of the racemic 6β, 7β, 8α- and 6β, 7β, 8β-trihydroxy-labdadienes, 2a and 2b respectively, were achieved starting from decalin 3via the enone 10. Diene 2a was found to be identical to crotomachlin, a diterpene from Croton macrostachys. in which the configuration at C(8) has not been established with certainty.