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异喹啉盐具有两个亲电位点, 用它与双亲核试剂发生去芳构化/环化反应, 是高效构建异喹啉桥环结构的有效策略. 然而, 这一策略主要集中在1,3-桥环结构的合成. 最近利用异喹啉盐与4-羟基香豆素反应, 首次实现了二氢异喹 啉-3-酮-1,4-桥环的合成. 但是, 当用环状1,3-二酮代替4-羟基香豆素反应时, 意外地得到了异喹啉-1,3,4(2H)-三酮. 利用高分辨质谱分析发现, 这一意外转化是由于环状1,3-二酮发生O-亲核取代后, 消除2-溴-1,3-环状二酮, 得到4-溴异喹啉-3(2H)-酮. 该中间体发生两次连续水解/空气氧化后, 得到了异喹啉-1,3,4(2H)-三酮. 基于此机理的认识, 向反应体系中添加催化量的三氟甲烷磺酸后, 成功抑制了环状1,3-二酮的O-亲核取代反应, 顺利得到了二氢异喹啉-3-酮的1,4-桥环结构(33个反应实例). 反应条件温和, 提供了一种构建异喹啉1,4-桥环骨架的高效合成方法. 相似文献
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发展了一种苯甲酰胺自由基自由基环化制备α-官能化叔烷基取代的异喹啉二酮的新反应。此环化反应以偶氮试剂为α-取代叔烷基自由基源物质,利用碘化亚铜/空气体系催化N-烷基-N-甲基丙烯酰基苯甲酰胺发生环化,经过串联自由基加成/环化/碳-碳键形成过程,一步构建了三重碳-碳键,以41%~71%的产率合成了一系列异喹啉二酮及其衍生物。特别值得提出得是,此研究发展了一种新型α-官能叔烷基自由基源物质,发现了一种同时引入两个α-官能叔烷基片段的串联新反应。反应底物适应范围广,反应高效,催化体系廉价实用,为具有潜在药用价值的含α-取代季碳中心的异喹啉二酮及衍生物的合成提供了一条廉价、简单、快捷的新途径。 相似文献
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In this paper, we report the synthesis of carbohydrate-derived 1,7-enynes and subsequent metathesis to yield polyhydroxylated 1-vinylcyclohexenes. For example, we converted D-glucose 2 to the (6,7)-dideoxy-D-gluco-hept-6-ene-pyranose 7, which led to the desired 1,7-enyne 16. The ring-closing metathesis of this 1,7-enyne 16 with the second generation Grubbs catalyst, under Mori's conditions, gave the corresponding polyhydroxylated 1-vinylcyclohexene 25 in 76% yield. The conversion of several aldohexoses into polyhydroxylated 1-vinylcyclohexenes was carried out with satisfying yields. We report also the synthesis of two carbohydrate-derived ethyl 8-yn-2-enoates from D-glucose derivatives. 相似文献
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Ojima I Vu AT Lee SY McCullagh JV Moralee AC Fujiwara M Hoang TH 《Journal of the American Chemical Society》2002,124(31):9164-9174
The reaction of a 1,6-enyne with a hydrosilane catalyzed by Rh(acac)(CO)(2), Rh(4)(CO)(12), or Rh(2)Co(2)(CO)(12) under ambient CO atmosphere or N(2) gives 2-methyl-1-silylmethylidene-2-cyclopentane or its heteroatom congener in excellent yield through silylcarbocycization (SiCaC) process. The same reaction, but in the presence of a phosphite such as P(OEt)(3) and P(OPh)(3) under 20 atm of CO, affords the corresponding 2-formylmethyl-1-silylmethylidene-2-cyclopentane or its heteroatom congener with excellent selectivity through carbonylative silylcarbocycization (CO-SiCaC) process. The SiCaC reaction has also been applied to a 1,6-enyne bearing a cyclohexenyl group as the alkene moiety and a 1,7-enyne system. The functionalized five- and six-membered ring systems obtained by these novel cyclization reactions serve as useful and versatile intermediates for the syntheses of natural and unnatural heterocyclic and carbocyclic compounds. Possible mechanisms for the SiCaC and CO-SiCaC reactions as well as unique features of these processes are discussed. 相似文献
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The synthesis of a series of stereochemically defined spirocyclic compounds and their use as novel P2-ligands for HIV-1 protease inhibitors are described. The bicyclic core of the ligands was synthesized by an efficient nBu 3SnH-promoted radical cyclization of a 1,6-enyne followed by oxidative cleavage. Structure-based design, synthesis of ligands, and biological evaluations of the resulting inhibitors are reported. 相似文献
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Arimitsu S Fernandez B Pozo CD Fustero S Hammond GB 《The Journal of organic chemistry》2008,73(7):2656-2661
A scalable synthesis of 2,2-difluorohomopropargyl esters was achieved using a magnesium-promoted Barbier reaction of substituted difluoropropargyl bromides with alkyl chloroformates. These 2,2-difluorohomopropargyl esters were effective precursors in the synthesis of homopropargylic amides-by aminolysis using AlMe3, as well as of ketones-through the reaction of the corresponding Weinreb amides with Grignard reagents. Ring closing metathesis using difluorinated 1,7-enyne carbonyl compounds furnished six-membered diene products, which were used as susbstrates in a Diels-Alder reaction to afford 4,4-difluoroisoquinolin-3-ones. The [2 + 2 + 2] cycloaddition of alkynes with fluorinated 1,7-diyne amides gave 4,4-difluoro-1,4-dihydro-3(2H)-isoquinolinone derivatives regioselectively. 相似文献
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Min-Ruei Tsai 《Tetrahedron》2004,60(47):10637-10644
An original alternative approach to isoquinolines based on the installation of a benzene nucleus on a performed heterocyclic ring. Synthesis of 3,4-dihydrobenzo[g]isoquinoline-1(2H)-ones and 3,4-dihydroisoquinoline-1(2H)-ones via intramolecular electrophilic cyclization of 3,4-disubstituted lactams is reported. 相似文献
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[reaction: see text] 1alpha,25-Dihydroxyvitamin D(3) was synthesized by the Suzuki-Miyaura coupling of the A-ring intermediate 1, which was efficiently prepared from readily available 1,7-enyne 2, with the corresponding boronate compound of the C,D-ring portion. The method was applied to prepare des-C,D analogues of 1alpha,25-dihydroxyvitamin D(3). 相似文献
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Xu J Zuo G Jiao P Wang H Jin S Chan AS 《Rapid communications in mass spectrometry : RCM》2000,14(8):633-636
The mass spectrometric behaviour of six 2a,4-disubstituted 5-benzoyl-2-chloro-2a,3,4,5-tetrahydroazeto[1,2-a][1,5]benzodia zepin-1(2H)-ones has been studied with the aid of mass-analysed ion kinetic energy spectrometry and accurate mass measurements under electron impact ionization. All compounds show a tendency to eliminate a chlorine atom, a chlorine atom plus benzaldehyde, benzoyl radical, chloroketene or chlorine atom plus CO and H2O molecules to yield, respectively, [M-Cl]+ ions, 2a,4-disubstituted 2a,3-dihydroazeto[1,2-a][1,5]benzodiazepin-1(2H)-one ions, [M-PhCO]+ ions, 2,4-disubstituted 1-benzoyl-2,3-dihydro-1H-1,5-benzodiazepine ions, or 1,2,4-trisubstituted 1H-1,7-benzodiazonine ions, which could also be formed from [M-Cl]+ ions by loss of CO and H2O molecules simultaneously. The [M-Cl]+ ions could further lose benzoyl radical to form [M-Cl-PhCO]+ ions, or lose benzoyl amide and undergo a rearrangement to form 4,6-disubstituted 1-benzoazocine-2(1H)-one ions. The [M-PhCO]+ ions could eliminate NH to produce 2a,4-disubstituted 2,2a,3,4-tetrahydroazeto[1,2,-a]quinolin-1-one ions, which could further eliminate chloroketene, CO and/or HCl to produce some important ions, respectively. 2,4-Disubstituted 1-benzoyl-2,3-dihydro-1H-1,5-benzodiazepine ions could lose benzoyl radical to yield 2,4-disubstituted 2,3-dihydro-1H-1,5-benzodiazepine ions, which could further yield other small fragment ions by loss of propene/styrene or small fragments. 相似文献
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K. Kantminene G. Mikul'skene O. Hormi Z. I. Beresnevicius 《Chemistry of Heterocyclic Compounds》2002,38(4):422-428
Tetrahydro-1H,7H-benzo[ij]quinolizine-1,7-diones have been obtained by the cyclization of N-alkoxyphenyl-N-(2-carboxyethyl)--alanines. Fission of the ester bond occurs on cyclization of N-(4-ethoxyphenyl)-N-(2-carboxyethyl)--alanine, but the cyclization of the 3,4-dialkoxyphenyl derivative leads to the formation of 9-alkoxy-8-hydroxy-2,3,5,7-tetrahydro-1H,7H-benzo[ij]quinolizine-1,7-diones. The corresponding dioximes and diphenylhydrazones were obtained. 相似文献
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Liu X Xin X Xiang D Zhang R Kumar S Zhou F Dong D 《Organic & biomolecular chemistry》2012,10(29):5643-5646
A facile and efficient synthesis of substituted quinolin-2(1H)-ones is developed via intramolecular cyclization of penta-2,4-dienamides mediated by concentrated H(2)SO(4) (98%), and a mechanism involving the formation of a dicationic superelectrophile, and subsequent intramolecular nucleophilic cyclization reactions is proposed. 相似文献
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Catalytic hydrogenation of carbon-, nitrogen- and oxygen-tethered 1,6-diynes 1a-9a and 1,6-enynes 10a-18a using cationic Rh(I) precatalysts at ambient temperature and pressure enables reductive carbocyclization to afford 1,2-dialkylidene cyclopentanes 1b-9b and monoalkylidene cyclopentanes 10b-18b, respectively, in good to excellent yields and as single alkene stereoisomers. Notably, the 1,3-diene and alkene containing cyclization products 1b-9b and 10b-18b are not subject to over-reduction under the conditions of catalytic hydrogenation in which they are formed. Reductive cyclization 1,6-diyne 1a and 1,6-enyne 10a performed under an atmosphere of D(2) provides the carbocyclization products deuterio-1b and deuterio-10b, respectively, which incorporate two deuterium atoms. The collective data are consistent with a catalytic mechanism involving heterolytic activation of elemental hydrogen (H(2) + Rh(+)X(-) --> Rh-H + HX) followed by Rh(I)-mediated oxidative cyclization of the 1,6-diyne or 1,6-enyne substrates to afford (hydrido)Rh(III)-based metallocyclopentadiene and metallocyclopentene intermediates, respectively. These transformations represent the first examples of metal-catalyzed reductive carbocyclization mediated by hydrogen. 相似文献