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Synlett 1998; 1998(1): 76-78
DOI: 10.1055/s-1998-1576
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Synthesis of a Bicyclic Cation Related to Sterol Biosynthesis and Its Chemical Destiny, Part I

Mugio Nishizawa* , Hiroko Takao, Yoshihiro Iwamoto, Hidetoshi Yamada, Hiroshi Imagawa
  • *Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8055, Japan; E-mail: mugi@mb.infoeddy.ne.jp
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Publication History

Publication Date:
31 December 2000 (online)

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Synthesis of bicyclic tert-alcohol 1 has been accomplished by means of Hg(OTf)2-induced cyclization of tert-butyl bishomofarnesate as the key step. Bicyclic cation 2, related to the sterol biosynthesis, is generated by the reaction of 1 with BF3. The chemical destiny of the cation 2 was traced and it confirmed the structure of three kinds of cyclization products to be 3, 4, and 5. These tricyclic compounds are formed via trans-anti-trans 6/6/5 fused cation 6. The tricyclic product 3 is the stereoisomer with Corey's enzymatic cyclization product of a 2,3-oxidosqualene type epoxide. Selective formation of the trans-anti-trans 6/6/5 fused cation 6 as the intermediate that corresponds to the biosynthetic intermediate of a dammarane-type triterpenoid is noteworthy.

sterol biosynthesis - 6/6/5 fused tricyclic products - mercuric triflate - biomimetic olefin cyclization - migration of methyl group - stepwise mechanism

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