Total synthesis of optically active cotylenol, a fungal metabolite having a leaf growth activity. Intramolecular ene reaction for an eight-membered ring formation

✍ Scribed by Nobuo Kato; Hiroaki Okamoto; Hitoshi Takeshita

• Book ID: 104207312
• Publisher: Elsevier Science
• Year: 1996
• Tongue: French
• Weight: 880 KB
• Volume: 52
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(96)00059-2

✦ Synopsis

Starting from condensation of two iridoid synthons, (3S,8R)-benzyloxy-l-iriden-7-al and (3R)-7-chloro-l-iridene, cotylenol, one of the representative fusicoccane diterpenoids having 5-8-5-membered tricyclic carbon framework, is now synthesized for the first time via an eight-membered ring formation by an intramolecular ene reaction and subsequent introduction of an a-hydroxyl group.

I

Scheme 2. a) CrCI3-LAH/THF-DMF; b) TMSCI/pyridine; c) 9-BBN/THF; d) H202, NaOH; e)l Bu4NFfrHF; f) TBSCI, imidazole/DMF; 9) MsCVpyddine; h) Na, FeCI3/liq. NH3; j) PPTS/aq. THF. I Ene Cyclization to Construct the Tricyclic System and Conversion into Cotylenol. After