Hopane epoxide

Confirmation of the C-2ipH configuration in the hopane series has resulted from the X-ray analyses of adiantol (133) and zeorin (134).This has led to a reinterpretation of a previously reported correlation of zeorin and leucotylin (135). Full papers on the rearrangement of some tetrasubstituted epoxides in this series have appeared. 

Berti et al. found that the tetrasubstituted epoxide derivative (110 equation 44) of the triterpene hopane gave an efficient rearrangement to the ketone (111). 

The pentacyclic triterpene skeleton hopane is generated by 2,7-, 6,11-, 10,15-, 14,19-, and 18,22-cyclization of the carbenium ion in a fivefold chair conformation (as drawn) arising from regioselective protonation of the 2,3-double bond of squalene (but not of the 2,3-epoxide). This explains why hopanes are usually not hydroxylated in the 3-position. 

Homosecodaphniphyllic acid, methyl ester, K26 Homoterpenyl methyl ketone, Tl Homothujadicarboxylic acid, T7 Hopane, T4S Hopeaphenol, YIS Hopenone I, T4S Humulene dioxide, T30 Humulene epoxides, T30 Humulenols, T30 Hunteracine, K14 Hunterbumine, K8 Huratoxin, T39 Hydrastines, K3 Hydratropic acid, A41 3j8-hydroxyallocholanic acid, T49 Hydroxycitric acid, A30... 

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