8-Hydroxy-a-humulene

Fig. 8.13 Pathways employed for the pioduetion of noot-katone, 8-hydroxy-a-humulene, 8-hydroxyeadinene, and artemisinic aeid in microbial hosts. Further downstream metabolites like zerumbone, gossypol, and artemisinin are also shown. In studies using E. coli, an engineered mevalonate (MVA) pathway as well as the endogenous methyleiythritol phosphate (MEP) pathway and fame-syl diphosphate FTP) synthase support FPP production. When using S. cerevisiae as host, either the native (for...

A more complex example is the production of 8-hydroxy-a-humulene. This is the direct precursor of zerumbone, which is contained in Zingiber zerumbet ( shampoo ginger ). 8-Hydroxy-a-... 

Thus, reaction of humulene (1) with A -bromosuccinimide in aqueous acetone, or with hypobromous acid, gave a 1 1 mixture of 9-bromo-l,4,4-trimethyl-8-methylenecycloundeca-l,5-diene (2) and 5-bromo-8-hydroxy-4,8,ll,ll-tetramethyltricyclo[7.2.0.0 ]undecane (3), each isolated in 25% yield. In this tricyclic compound six neighboring asymmetric centers were formed in one step with a very high degree of stereoselectivity. ... 

In a similar manner, humulene 1,2-epoxide was efficiently transformed to 5-hydroxy-4,8,ll,ll-tetramethyltricyclo[6.3.0.0 ]undec-9-ene (13) using trimethylsilyl triflate.A small amount of tricyclohumulenol (14) was also obtained which was easily removed by column chromatography on silica gel. 

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