共查询到20条相似文献,搜索用时 31 毫秒
1.
Since the discovery of the radical mediated thiol‐ene and thiol‐yne reactions, these reactions have been employed in an intramolecular manner for the synthesis of sulfur‐containing heterocycles. Although closely related on a mechanistic basis, the thiol‐ene and thiol‐yne cyclization can differ greatly in regioselectivity and product distribution, with the thiol‐ene process being more predictable and thus attracting greater utilization. Herein, we review intramolecular thiyl‐radical addition reactions and the factors leading to the observed regioselectivity in examples in which both the 5‐exo and 6‐endo mode of cyclization are feasible. We highlight the applications of these important reactions for organic synthesis in the recent literature. 相似文献
2.
Intermolecular and intramolecular reactions of a one‐pot gold‐catalyzed epoxide rearrangement followed by an electrophilic addition to arylalkynes to synthesize 1‐arylnaphthalenes have been reported. The intramolecular reaction has been applied to synthesize 1‐arylnaphthalenes fused with saturated furan, pyran, pyrrole, and cyclopentane ring systems. 相似文献
3.
Xi‐Jie Dai Oliver D. Engl Thierry Len Stephen L. Buchwald 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3445-3449
Herein, we report a practical two‐step synthetic route to α‐arylpyrrolidines through Suzuki–Miyaura cross‐coupling and enantioselective copper‐catalyzed intramolecular hydroamination reactions. The excellent stereoselectivity and broad scope for the transformation of substrates with pharmaceutically relevant heteroarenes render this method a practical and versatile approach for pyrrolidine synthesis. Additionally, this intramolecular hydroamination strategy facilitates the asymmetric synthesis of tetrahydroisoquinolines and medium‐ring dibenzo‐fused nitrogen heterocycles. 相似文献
4.
Gold‐Catalyzed 1,2‐Acyloxy Migration/Intramolecular [3+2] 1,3‐Dipolar Cycloaddtion Cascade Reaction: An Efficient Strategy for Syntheses of Medium‐Sized‐Ring Ethers and Amines
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Changgui Zhao Dr. Xingang Xie Shuangshuang Duan Huilin Li Dr. Ran Fang Prof. Dr. Xuegong She 《Angewandte Chemie (International ed. in English)》2014,53(40):10789-10793
A highly efficient strategy for the formation of medium‐sized‐ring ethers and amines based on a gold‐catalyzed cascade reaction, involving enynyl ester isomerization and intramolecular [3+2] cyclization, has been developed. Various multisubstituted medium‐sized‐ring unsaturated ethers and amines were obtained through this transformation. This method represents one of the relatively few transition metal catalyzed intramolecular cycloaddition reactions for medium‐sized ring synthesis. 相似文献
5.
Tetsuro Shimo Shigeki Matsuzaki Kenichi Somekawa 《Journal of heterocyclic chemistry》1994,31(2):387-390
6-(ω-Alkenyl)-2-pyrones 3a-c and 8a, b were prepared and the photochemical reactions were investigated. Photosensitized reactions of 3b, c gave intramolecular [2+2]-cycloadducts 11b, c as tricyclic lactones, site-and regio-specifically. They are not frontier-orbital-controlled adducts. On the other hand, 3a, 8a, b afforded cyclobutenecarboxylic acids, 10a, 14a, b , respectively. The end-ester group at the side-chain is thought not to be effective for the intramolecular phptoaddition. 相似文献
6.
Iwao Omae 《Journal of organometallic chemistry》2007,692(13):2608-2632
There are three types of reactions with intramolecular five-membered ring compounds in organic syntheses: The first type is reactions involving intramolecular five-membered ring compounds which are utilized for the ease of synthesis of these compounds and the stability of the products. The second is reactions performed via intramolecular five-membered ring intermediates, because such intermediates are very reactive and labile compounds. The third is the metal-catalyzed reactions with the intramolecular five-membered ring compounds because these metal compounds have catalytic activities. The third type reactions involving intramolecular five-membered ring pincer compounds are also provided.The first type reactions include carbonylations, alkenylations, alkynylations, acylations, isocyanations, Diels-Alder reactions, etc. The second type reactions include carbonylations, cross-coupling reactions, hydroacylations, ring expansion reactions, carbocyclizations, etc. The third type reactions include cross-coupling reactions, rearrangements, metatheses, reductions, Michael reactions, dehydrogenations, Diels-Alder reactions, etc. 相似文献
7.
Peter N. Carlsen Tyler J. Mann Prof. Amir H. Hoveyda Prof. Alison J. Frontier 《Angewandte Chemie (International ed. in English)》2014,53(35):9334-9338
The first synthesis of (±)‐tetrapetalone A‐Me aglycon is described. Key bond‐forming reactions include Nazarov cyclization, a ring‐closing metathesis promoted with complete diastereoselectivity by a chiral molybdenum‐based complex, tandem conjugate reduction/intramolecular aldol cyclization, and oxidative dearomatization. 相似文献
8.
Ring‐opening polymerisation is a mean to transform stepwise polymerisation reactions into chain reactions, the cyclic monomers being prepared by intramolecular condensation of open chain bifunctional monomers [1, 2]. The ring‐opening polymerisation is initiated most conveniently with ionic initiators which may be of macromolecular structure. Thus, block‐ and graft copolymers are obtained. 相似文献
9.
Dr. Dhananjayan Vasu Prof. Dr. Hideki Yorimitsu Prof. Dr. Atsuhiro Osuka 《Angewandte Chemie (International ed. in English)》2015,54(24):7162-7166
Two new palladium‐catalyzed reactions of aromatic sulfur compounds enabled the conversion of dibenzothiophenes into triphenylenes in four steps. This transformation of one aromatic framework into another consists of 1) 4‐chlorobutylation of the dibenzothiophene to form the corresponding sulfonium salt, 2) palladium‐catalyzed arylative ring opening of the sulfonium salt with a sodium tetraarylborate, 3) an intramolecular SN2 reaction to form a teraryl sulfonium salt, and 4) palladium‐catalyzed intramolecular C? S/C? H coupling through electrophilic palladation. Symmetrical as well as unsymmetrical triphenylenes of interest were synthesized in a tailor‐made fashion in satisfactory overall yields. 相似文献
10.
Zhiguo Zhang Junlong Li Guoqing Huang Kai Sun Guisheng Zhang Nana Ma Qingfeng Liu Tongxin Liu 《中国化学》2016,34(12):1309-1320
A convenient copper‐catalyzed approach has been developed for the synthesis of substituted spiro‐fused pyrazolin‐5‐ones from readily available cyclopropyl O‐acyl ketoximes via an intramolecular N? N bond formation reaction. These catalytic reactions proceed in excellent yields with a broad scope. 相似文献
11.
For the study of thiirane reactions with nucleophiles 8-halo-1,3-dimethyl-7-(thiiran-2-ylmethyl)-3,7-dihydro-1H-purine-2,6-diones that did not form polymeric products through intramolecular heterocyclization into dihydrothiazolopurine
derivatives were selected as model compounds. The possibility to employ the model thiiranes for the study of reactions with
various nucleophiles was demonstrated. 相似文献
12.
Transition‐Metal‐Free Intramolecular Carbene Aromatic Substitution/Büchner Reaction: Synthesis of Fluorenes and [6,5,7]Benzo‐fused Rings
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zhenxing Liu Haocheng Tan Long Wang Tianren Fu Ying Xia Dr. Yan Zhang Prof. Dr. Jianbo Wang 《Angewandte Chemie (International ed. in English)》2015,54(10):3056-3060
Intramolecular aromatic substitution and Büchner reaction have been established as powerful methods for the construction of polycyclic compounds. These reactions are traditionally catalyzed by RhII catalysts with α‐diazocarbonyl compounds as the substrates. Herein a transition‐metal‐free intramolecular aromatic substitution/Büchner reaction is presented. These reactions use readily available N‐tosylhydrazones as the diazo compound precursors and show wide substrate scope. 相似文献
13.
Liliana Boiaryna Dr. Mohamed Kamal El Mkaddem Dr. Catherine Taillier Prof. Vincent Dalla Dr. Mohamed Othman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(44):14192-14200
Gold catalysts have been applied in cascade‐type reactions for the synthesis of different nitrogen‐based compounds. The reactions likely proceed by a new gold‐catalyzed cascade intermolecular α‐amidoalkylation/intramolecular carbocyclization cascade process by unifying both the σ‐ and π‐Lewis acid properties of the gold salts. In the first part of this report we show that the σ‐Lewis acidity of gold(I) and gold(III) could be exploited to efficiently catalyze the nucleophilic substitution of various alkoxy‐ and acetoxylactams. The reaction was found to be applicable to a wide range of cyclic N‐acyliminium ion precursors and various nucleophiles, including allyltrimethylsilane, silyl enol ethers, arenes, and active methylene derivatives. As a logical progression of this study, a combined hard/soft binary catalytic gold system was then used to implement an unprecedented tandem intermolecular Friedel–Crafts amidoalkylation/intramolecular hydroarylation sequence allowing an expedient access to new, complex, fused polyheterocyclic structures from trivial materials. 相似文献
14.
Iwao Omae 《应用有机金属化学》2010,24(5):347-365
Carbonyl group‐containing organometallic intramolecular‐coordination five‐membered ring compounds are easily synthesized by the following five reaction methods: (1) cyclometalation, especially, orthometalation reactions; (2) the reactions of the moieties of an unsaturated carbon? carbon bond attached to a carbonyl group (C?C? CO, C?C? CO); (3) the reactions of an unsaturated carbon? carbon bond with carbon monoxide (C?C and CO, C?C and CO); (4) carbonylative ring expansion reactions; and (5) others. These compounds are very easily and regio‐specifically synthesized with many kinds of metal compounds, including both transition metals and main group metals. Many of such the reactions are easily applied to organic syntheses. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
15.
A Facile Access to Polyfunctional Oxygen‐containing Heterocycles via Intramolecularly Formed Protic Oxonium Ylide Trapping Processes
下载免费PDF全文
![点击此处可从《化学:亚洲杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Based on the assumption that intramolecularly formed protic oxonium ylides could be trapped by electrophiles, transition‐metal‐catalyzed reactions of diazoesters bearing a primary hydroxy group with electron‐deficient aldehydes and isatins were examined. Good to high chemo‐ and diastereoselectivities were achieved with reactions catalyzed by Cu(hfacac)2. The reactions were assumed to occur via tandem intramolecular protic oxonium ylide formation and subsequent aldol‐type addition. They not only provided an efficient entry to 3‐substituted 1,4‐dioxan‐2‐one heterocycles with at least one quaternary carbon center but also provided experimental evidence for a stepwise pathway for the transition‐metal‐catalyzed intramolecular O? H insertion of diazo compounds. 相似文献
16.
The catalytic hydrogenation of α-mono- and bis-cyanoethylated aldimines The catalytic hydrogenation of α-mono- and -bis-cyanoethylated aldimines using nickel catalysts was studied. Piperidine derivatives are formed in intramolecular cyclization reactions. The hydrogenation products of α-bis-cyanoethylated ketones, the decahydro-1, 8-naphthyridines, are observed here only as by-products. 相似文献
17.
18.
A General Approach to Site‐Specific,Intramolecular C−H Functionalization Using Dithiocarbamates
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Christina G. Na Prof. Erik J. Alexanian 《Angewandte Chemie (International ed. in English)》2018,57(40):13106-13109
Intramolecular hydrogen atom transfer is an established approach for the site‐specific functionalization of unactivated, aliphatic C?H bonds. Transformations using this strategy typically require unstable intermediates formed using strong oxidants and have mainly targeted C?H halogenations or intramolecular aminations. Herein, we report a site‐specific C?H functionalization that significantly increases the synthetic scope and convergency of reactions proceeding via intramolecular hydrogen atom transfer. Stable, isolable N‐dithiocarbamates are used as precursors to amidyl radicals formed via either light or radical initiation to efficiently deliver highly versatile alkyl dithiocarbamates across a wide range of complex structures. 相似文献
19.
Hao Yu Dr. Zhen Li Prof. Dr. Carsten Bolm 《Angewandte Chemie (International ed. in English)》2018,57(37):12053-12056
A general and atom‐economical method for the synthesis of cyclic sulfoximines by intramolecular imidations of azido‐containing sulfoxides using a commercially available FeII phthalocyanine (FeIIPc) as catalyst has been developed. The method conveys a broad functional group tolerance and the resulting three‐dimensional heterocycles can be modified by cross‐coupling reactions. 相似文献
20.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(40):13290-13293
Intramolecular hydrogen atom transfer is an established approach for the site‐specific functionalization of unactivated, aliphatic C−H bonds. Transformations using this strategy typically require unstable intermediates formed using strong oxidants and have mainly targeted C−H halogenations or intramolecular aminations. Herein, we report a site‐specific C−H functionalization that significantly increases the synthetic scope and convergency of reactions proceeding via intramolecular hydrogen atom transfer. Stable, isolable N‐dithiocarbamates are used as precursors to amidyl radicals formed via either light or radical initiation to efficiently deliver highly versatile alkyl dithiocarbamates across a wide range of complex structures. 相似文献