(A) convenient method for the preparation of cyclo-heptenones : its application to hydroazulene skeletons = 시클로 헵테논류의 간편한 제조방법 및 이를 이용한 히드로 아줄렌 골격의 합성 its application to hydroazulene skeletons

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Cyclohept-3-3nones were prepared in four to five steps starting from cyclopentanone sily enol ether in high overall yields(42-75\%). Silyl enol ethers of cyclopentanones were converted to dichlorobicyclo [3.2.0] heptanones(75-88\%) via [2+2] cycloaddition with dichloroketene generated from trichloroacetyl chloride. Dechlorination of the dichlorobicyclic ketones was performed by treatment with tributyltin hydride in the presence of AIBN to give bicyclic ketones(89-94\%). The ketones were either reduced with sodium borohydride or treated with methylmagnesium bromide to give bicyclic secondary or tertiary alcohols(95-98\%). The secondary alcohols were subjected to mesylation ($CH_3SO_2Cl$, $Et_3N$/DCM) and fragmentation (n-$Bu_4NF$/THF) condition to give cyclohpt-3-enones(59-64\%). On the other hand the tertiary bicyclic alcohols underwent fragmentation spontaneously during mesylation condition to give the corresponding cyclohept-3-enones almost quatitatively. All the cyclohept-3-enones were converted into the corresponding cyclohept-2-enones quatitatively by treatment with p-TsOH. Similary, thermal [2+2]cycloaddition of silyl enol ethers with dithisubstituted ketene gave the corresponding cycloadducts. However, when the cycloadducts were treated with $Bu_4NF$, $C_1$-$C_7$ bond cleavage occurred exclusively resulting diketones in almost quantitative yield. 6-Methylbicyclo [5.3.0] dec-10-en-2-one having trans configuration between $C_6$-methyl and $C_7$-proton was synthesized by applying the above methodology for cycloheptenone synthesis. The 5-methyl-1-(trimethyl siloxy) bicyclo [3.2.0]heptanone was treated with Grignard reagent of 2-(2-bromoethyl)-1,3-dioxane, and subsequent fragmentation produced the corresponding cyclohept-3-enone. Stereoselective hydrogenation of cycloheptenone was achieved in the presence of rodium on alumina affording a stereoisomer mixture of cis and trans(15:1). Acid catalyzed cyclization of cycloheptanone derivative was carried out by Hea...
Advisors
Pak, Chwang-SiekKim, Yong-Hae박창식김용해
Description
한국과학기술원 : 화학과,
Publisher
한국과학기술원
Issue Date
1991
Identifier
61617/325007 / 000835515
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 화학과, 1991.8, [ vii, 133 p. ]

URI
http://hdl.handle.net/10203/31354
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=61617&flag=dissertation
Appears in Collection
CH-Theses_Ph.D.(박사논문)
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