(A) free radical-mediated acylation and carboxylation approach = 자유라디칼을 이용한 아실화 및 카르복실화 반응 접근

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Free radical-mediated acylation reactions were studied with n-iodo thioesters and selenoesters. The treatment of n-iodo thio-and seleno-esters with bis(tributyltin) under irradiation at 300 nm afforded cyclic ketone products in good yields. The reaction mechanism involved intramolecular addition of an alkyl radical to carbonyl group and subsequent $\beta$ -elimination of PHS or PHSe radical which reacts with bis(tributyltin) to propagate a chain. Both thio- and seleno-esters were utilized as carbonyl equivalent radical acceptors in radical cyclizations, where selenoesters are more efficient than thioesters due to the better leaving ability of PHSe group. Free radical-mediated carboxylations were achieved with carbonyl derivatives and 1,2-diketone derivatives. According to MOPAC calculations, S-phenyl chlorothioformate has the lowest LUMO eneergy among carbonyl derivatives tested in this study. The intermolecular addition of primary, secondary and sterically hindered tertially alkyl radicals to S-phenyl chlorothioformate under irradiation at 300 nm gave the corresponding thioesters in reasonably good yields. Under the similar conditions, the reaction of methyl oxalyl chloride among 1,2-diketone derivatices with alkyl iodides and bis(tributyltin) under irradiation at 350 nm afforded the corresponding acid chlorides as major products along with small amount of methyl esters. The radical rearrangement of mixed anhydrides was studied. Anhydride groups could participate in the radical rearrgement reaction as radical aceptors by introducing electron-withdrawing substituents into anhydride carbonyl groups, where the substituents lowered LUMO energy of the anhydride carbonyl carbon. 1,2-, 1,4- and 1,5-rearrangements were achieved with mixed ahnydrides in good yields. The reactions proceeded via addition-elimination mechanism as shown in well-recognized ketone-carbonyl rearragement. Phosphate and phosphinyl groups as substituents gave rearranged products in moderate yi...
Advisors
Kim, Sung-Gakresearcher김성각researcher
Description
한국과학기술원 : 화학과,
Publisher
한국과학기술원
Issue Date
1999
Identifier
151506/325007 / 000955336
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 화학과, 1999.2, [ iii, 130 p. ]

Keywords

Selenoesters; Thioesters; Radical; Carboxylation; Acylation; Anhydride; 무수물; 셀레노에스테르; 티오에스테르; 라디칼; 카르복실화; 아실화

URI
http://hdl.handle.net/10203/31498
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=151506&flag=dissertation
Appears in Collection
CH-Theses_Ph.D.(박사논문)
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