Synthetic Photochemistry. XLII. Total Synthesis of Cycloaraneosene, a Fundamental Hydrocarbon of 5–8–5-Membered Tricydic Diterpenoid fromSordaria araneosa
Digging up skeletons: We report the identification and the functional characterization of two terpene cyclases (DtcycA and DtcycB) that were mined from the genome of Streptomyces sp. SANK 60404. DtcycA and DtcycB are novel bacterialditerpenecyclases for the synthesis of the cembraneskeleton.
Total Synthesis of Cycloaraneosene, a Fundamental Hydrocarbon of “epi”-Fusicoccane Diterpenoids, and the Structure Revision of Its Congener, Hydroxycycloaraneosene
作者:Nobuo Kato、Shinya Tanaka、Hitoshi Takeshita
DOI:10.1246/cl.1986.1989
日期:1986.11.5
The 5-8-5-membered tricyclic diterpene, cycloaraneosene, has been totally synthesized via the stereoselective condensation of two units of optically active iridoids, Cope rearrangement and chemical reduction of the tetrasubstituted C=C bond. The NMR spectrum of synthetic 9α-hydroxycycloaraneosene was not identical with the congener product, and the natural alcohol is likely to be 8β-hydroxyl derivative.
Structure Elucidation of “Hydroxycycloaraneosene” by Unambiguous Total Synthesis. An Eight-Membered Ring Formation via a Lewis Acid-Catalyzed Ene-Reaction
was further converted to cycloaraneosene and its congener, “hydroxycycloaraneosene”. Total synthesis of the latter established its structure to be 8β-hydroxy derivative, not as the originally-proposed 9α-.
The Total Synthesis of 8β-Hydroxycycloaraneosene by Means of an Eight-Membered Ring-Formation via a Lewis Acid-Catalyzed Ene Reaction. Confirmation of Its Natural Occurrence
An improved eight-membered ring closure by means of a Lewis-acid-catalyzed ene reaction was applied to the synthesis of cycloaraneosene and its congener, “hydroxycycloaraneosene.” Comparisons of the NMR spectral data of the synthetic and natural compounds established that the natural product possesses an 8β-hydroxy structure, not the originally proposed 9α-hydroxy one.