Macrocyclic Diterpenoids and their Cyclization Products

Incensole (113) and isoincensole oxide (114) have been synthesized from muku-lol by methods which allow the determination of their stereochemistry. The X-ray analysis of a thunbergadienediol (115), obtained from Greek tobacco, has been described.  

A large number of cembrane diterpenoids have been obtained from marine organisms, particularly soft corals. 2-Hydroxynephthenol (116) was isolated from Litophyton viridis. A dehydro-derivative (117) of epoxynephthenol was 

The oxidation of various cembrane diterpenoids by chromium trioxide has been noted. The full paper on the X-ray analysis of ovatodiolide and ovatodiolic acid has appeared. Detailed n.m.r. studies have led to the structures (124)—(127) 

Odoracin (141) is an insecticidal constituent of Daphne odora which contains an unusual deca-2,4-dienoate ortho-ester function. Gnidilatidin (142) and gnidi- 

Kogiso, K. Wada, and K. Munakata, Agric. and Biot. Chem. (Japan), 1976, 40, 2119. 

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Synthetic endeavours have continued in the diterpenoid series. The cyclization of geranylgeranic acid chloride to derivatives of cembrene, and their conversion into cembrene itself, have been described. Some further extensions of the route to macrocyclic diterpenoids based on the intramolecular cyclization of epoxysulphides and the subsequent modification of the macrocylic product have been described. ... 

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