Oleanene derivatives

The ring a lactam of-glycyrrhetic acid has been reported.The results of studies into the biosynthesis of oleanene derivatives in the leaves of Calendula officinalis have been published. 

The methyl resonances of several oleanene derivatives have been assigned using lanthanide shifts and homonuclear INDOR techniques to measure the nuclear Overhauser effects between methyl signals. The assignments of the resonances of a series of 18jSH- and 18aH-oleanenes have been published. The potential use of molecular rotation differences in the identification of triterpenoid structures has been discussed. ... 

Olean-12-enes are converted into the corresponding 12-chloro-derivatives, e.g. (121), on reaction with a gaseous mixture of nitrosyl chloride and chlorine in pyridine solution. This method has been used to separate natural mixtures of oleanenes and ursenes since the latter are inert under these conditions. The glycyrrhetic acid derivative (122) afforded the fluorinated product (123) on treatment with CF3OF at —70 °C. (123) decomposed readily in polar solvents to give a rearranged product which has been assigned the novel structure (124). 

C30H52, Mr 412.74, 18a-0. mp. 210°C, [aJo +40.3° (CHCI3), a pentacyclic triterpene hydrocarbon occurring in crude oil. O. represents the saturated skeleton of /3- amyrin. Numerous related triterpenes are derived from O. e.g., the hydrocarbons II,l3(l8)-olea-nadiene, (C30H48O, Mr 424.71, mp. 226-227°C), 12-oleanene (C30H50, Mr 410.73, mp. 162-164°C), and 18-oleanene (mp. 174-175 °C) from polypody species (Polypodium), as well as various polyols (see table) that are widely distributed as glycosides ( sap-onins). 

Boswellic acids are constituents of incense (olibanum) from Boswellia serrata and B. carterii (Burseraceae) a-boswellic acid incorporates the 12-oleanene core structure (section 6.3.3), while 12-ursene is the parent hydrocarbon of p-boswellic acid and ketoboswellic acid. Various derivatives of boswellic acids are reported to have antiinflammatory properties and therefore are suggested to be potential cortisone substitutes. 

Alam MS, Chopra N, Ali M, Niwa M (1996) Oleanene and stigmasterol derivatives from Ambroma augusta. Phytochemistry 41 1197-1200... 

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