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Total synthesis of the phytopathogen (+)-fomannosin

Peng, Xiaowen
http://rave.ohiolink.edu/etdc/view?acc_num=osu1155158634

Abstract Details

2006, Doctor of Philosophy, Ohio State University, Chemistry.
Fomannosin (1) is a sesquiterpene metabolite isolated in 1967 from the medium of the still culture of the wood-rotting fungus, Fomes annosus (Kr.) Karst. It was found to be toxic toward 2-year-old pinus tadae seedlings, Chlorella pyrenoidose, and certain bacteria. Fomannosin features a unique highly strained methylenecyclobutene unit and a reactive doubly unsaturated lactone. It is very sensitive toward both acid and base, posing a considerable challenge to synthetic chemists. The enantioselective total synthesis of (+)-fomannosin was completed in 35 steps starting from known tosylate 13. A zirconocene-mediated ring contraction reaction of vinylated furanosides 20 or 21 was utilized to construct the highly substituted cyclobutane 27. The cyclopentene ring was assembled through a ring-closing metathesis reaction. The lactone ring was then installed by a Knoevenagel condensation of thioester 54. Introduction of the cyclopentanone functionality was accomplished through a dihydroxylation, oxidation and SmI2-mediated á-deoxygenation reaction sequence to provide lactones 61 and 62. After the PMB protecting group was removed by trifluoroacetic acid under anhydrous conditions, the first dehydration was effected through the formation of a cyclic sulfite. The second dehydration was achieved through the elimination of trifluoromethanesulfonic acid. Deprotection of the TBS ether led to the isolation of (+)-fomannosin.
Leo Paquette (Advisor)
Chemistry, Organic

Recommended Citations

Citations

  • Peng, X. (2006). Total synthesis of the phytopathogen (+)-fomannosin [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1155158634

    APA Style (7th edition)

  • Peng, Xiaowen. Total synthesis of the phytopathogen (+)-fomannosin. 2006. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1155158634.

    MLA Style (8th edition)

  • Peng, Xiaowen. "Total synthesis of the phytopathogen (+)-fomannosin." Doctoral dissertation, Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1155158634

    Chicago Manual of Style (17th edition)

osu1155158634
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© 2006, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.