Synthetic studies toward total synthesis of Nopsan-4-ol and Delnudine = 놉산-4-올과 델누딘의 전합성에 관한 연구

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Development of new synthetic methodologies and their applications to the total synthesis of natural products were studied. In the course of synthesis of tricyclo-[4.3.2.$0^{1,5}$] undecane structure, unusual 6-exo radical cyclization was observed. Most of 2,2-disubstituted cyclopentene derivatives cyclized to produce tricyclo-[4.3.2.$0^{1,5}$] undecane through radical reaction sequence, which involved cyclopropyl methyl radical mediated rearrangement. However, in the case of 146a, unusual 6-exo-radical cyclization proceeded due to stereochemistry of secondary hydroxyl group. Tricyclic 151, prepared from β-keto ester 136, was used as a key intermediate for the total synthesis of Nopsan-4-ol. 151 was converted to Nopsan-4-ol by introduction of methyl group via 1,4-addition at C-6, methylation at C-4 position, and stereoselective reduction of olefin. Synthetic method used in the construction of tricyclo-[4.3.2.$0^{1,5}$] undecane was also applied to the total synthesis of Delnudine. BC-ring of Delnudine was prepared through that radical cyclization and rearrangement. After manipulation of functional groups of B-ring, A-ring of Delnudine was prepared through a regioselective alkylidene carbene C-H insertion derived from alkylation of trimethylsilyl-diazomethyl lithium followed by Peterson olefination and α -elimination, and then ozonolysis followed by aldol condensation of resulting cyclopentene. Some manipulations of A-ring were studied to introduce a functional group on unactivated C-18 position. A noteworthy aspect of this synthesis is a one-pot construction of tricyclic ring system.
Advisors
Lee, Hee-Yoonresearcher이희윤researcher
Description
한국과학기술원 : 화학과,
Publisher
한국과학기술원
Issue Date
2004
Identifier
237516/325007  / 000975273
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 화학과, 2004.2, [ iii, 145 p. ]

Keywords

RADICAL; TOTAL SYNTHESIS; DELNUDINE; NOPSAN-4-OL; CYCLIZATION REACTION; 고리화반응; 라디칼; 전합성; 델누딘; 놉산-4-올

URI
http://hdl.handle.net/10203/31623
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=237516&flag=dissertation
Appears in Collection
CH-Theses_Ph.D.(박사논문)
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