Neohopanes

NEW NEOHOPANE TRITERPENOIDAL SAPONIN GLYCOSIDES FROM GLIMUS LOTOIDS VAR. DECTAMNOIDS... 

Key Word index—G//n f lotoids var. dectaminoids, Molluginaceae neohopane, triterpenoidal... 

Methyl shifts in hopane subsequently lead to neohopane (C-28 methyl from C-18 to C-17), femane (C-27-methyl from C-14 to C-13 C-26 methyl from C-8 to C-14), adianane (C-25 methyl from C-10 to C-9) and, finally, filieane (C-24 methyl from C-4 to C-5). In another pathway, the eyelopentane ring of hopane expands to a eyelohexane substmeture involving a shift of earbon atom C-17 from C-21 to C-22, thus generating gammaeerane. 

Stereoisomers of hopane as the parent hydroearbon of about 100 naturally abundant hopane triterpenes are isolated in small amounts from oil slate and petroleum of various provenanee. Hydroxylated hopanes sueh as (-l-)-6a,22-hopanediol are found to oeeur in some liehens and, assoeiated with (-l-)-22(29)-hopen-6a,2ip-diol, in the roots of Iris missouriensis (Liliaeeae). Neohopanes exemplified by (-l-)-12-neo-hopen-3p-ol from Rhododendron linearifolium (Erieaeeae) rarely oeeur as natural produets. 

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