Tin-free radical carbon-carbon bond forming reactions = 유기주석화합물을 사용하지 않는 라디칼 탄소-탄소 결합반응

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The organotin-mediated radical reactions have greatly advanced in synthetic organic chemistry, but have many limitations for industrial application due to inherent toxicity. To overcome these problems, we focused on the development of tin-free radical carbon-carbon bond forming reactions. Decarboxylative acylation of new thiohydroxamte esters, which is less reactive and more stable than Barton’s ester, was developed. This active esters were easily prepared from the coupling of various carboxylic acids with N-methylhydroxydithiocarbamate. Primary, secondary and tertiary moieties worked well, yielding corresponding oxime ethers derivatives in high yields under thermal or photochemical condition. Synthetically useful tin-free radical acylation, vinylation, allylation and cyanation reactions using alkyl allyl sulfones as radical precursors were investigated. Alkyl allyl sulfones were highly efficient and reliable radical precursors for the generation of primary alkyl radicals under tin-free conditions and could be successfully applied for carbon-carbon bond formations. The radical alkylation of carboxylic amides was studied with ketene O,N-acetal (56) as radical alkylating reagent and was achieved by the addition of an alkyl radical to a ketene O,N-acetal and the subsequent cleavage of N-O bond. Alkyl halides activated with an α-electron-withdrawing group and simple alkyl halides underwent cleanly alkylations under tin-free or tin-catalyzed conditions. In addition, radical-mediated γ-alkylation of α,β-unsaturated carboxylic amides under tin-free conditions was also achieved by the selective γ-addition of alkyl iodides and bromides bearing a-electron-withdrawing group to diene O,N-acetals (75a-d). This approach could be further extended to the g-functionalizations using hetero groups such as phenylsulfanyl and phenylsulfonyl. $Et_3B$-initiated radical alkylations of carbonyl compounds using O-acetyl (89) and O-tert-butyldiphenylsilylhydroxyenamines (93) as radical a...
Advisors
Kim, Sung-Gakresearcher김성각researcher
Description
한국과학기술원 : 화학과,
Publisher
한국과학기술원
Issue Date
2005
Identifier
244517/325007  / 020015240
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 화학과, 2005.2, [ iii, 206 p. ]

Keywords

Tin-free; radical reactions; 탄소-탄소결합반응; 라디칼 반응; carbon-carbon bond formation

URI
http://hdl.handle.net/10203/31644
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=244517&flag=dissertation
Appears in Collection
CH-Theses_Ph.D.(박사논문)
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