共查询到20条相似文献,搜索用时 62 毫秒
1.
Bioinspired Intramolecular Diels–Alder Reaction: A Rapid Access to the Highly‐Strained Cyclopropane‐Fused Polycyclic Skeleton
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Prof. Dr. Shifa Zhu Zhengjiang Guo Zhipeng Huang Prof. Dr. Huanfeng Jiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(9):2425-2430
A bioinsipred gold‐catalyzed tandem Diels–Alder/Diels–Alder reaction of an enynal and a 1,3‐diene, forming the highly‐strained benzotricyclo[3.2.1.02,7]octane skeleton, was reported. In contrast, a Diels–Alder/Friedel–Crafts tandem reaction occurred instead when silver salts were used as the catalyst. Although both reactions experienced the similar Diels–Alder reaction of a pyrylium intermediate with a 1,3‐diene, they have different reaction mechanisms. The former proceeded with a stepwise Diels–Alder reaction, while the latter one with a concerted one. 相似文献
2.
Palladium‐Catalyzed CH Activation of N‐Allyl Imines: Regioselective Allylic Alkylations to Deliver Substituted Aza‐1,3‐Dienes
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)
Prof. Dr. Barry M. Trost Dr. Subham Mahapatra Dr. Martin Hansen 《Angewandte Chemie (International ed. in English)》2015,54(20):6032-6036
A new mode of activation of an imine via a rare aza‐substituted π‐allyl complex is described. Palladium‐catalyzed C(sp3)? H activation of the N‐allyl imine and the subsequent nucleophilic attack by the α‐alkyl cyanoester produced the 1‐aza‐1,3‐diene as the sole regioisomer. In contrast, nucleophilic attack by the α‐aryl cyanoester exclusively delivered the 2‐aza‐1,3‐diene, which was employed in an inverse‐electron‐demand Diels–Alder reaction for heterobiaryl synthesis. 相似文献
3.
《Chemical record (New York, N.Y.)》2018,18(6):570-586
Functional polymers are widely employed in various areas of biomedical sciences. In order to tailor them for desired applications, facile and efficient functionalization of these polymeric materials under mild and benign conditions is important. Polymers containing reactive maleimide groups can be employed for such applications since they provide an excellent handle for conjugation of thiol‐ and diene‐containing molecules and biomolecules. Until recently, fabrication of maleimide containing polymeric materials has been challenging due to the interference from the highly reactive double bond. A Diels‐Alder/retro Diels‐Alder reaction sequence based strategy to transiently mask the maleimide group provides access to such polymeric materials. In this personal account, we summarize contributions from our group towards the fabrication and functionalization of maleimide‐containing polymeric materials over the past decade. 相似文献
4.
Pascal Vermeeren Trevor A. Hamlin Israel Fernndez F. Matthias Bickelhaupt 《Angewandte Chemie (International ed. in English)》2020,59(15):6201-6206
The Lewis acid(LA)‐catalyzed Diels–Alder reaction between isoprene and methyl acrylate was investigated quantum chemically using a combined density functional theory and coupled‐cluster theory approach. Computed activation energies systematically decrease as the strength of the LA increases along the series I2<SnCl4<TiCl4<ZnCl2<BF3<AlCl3. Emerging from our activation strain and Kohn–Sham molecular orbital bonding analysis was an unprecedented finding, namely that the LAs accelerate the Diels–Alder reaction by a diminished Pauli repulsion between the π‐electron systems of the diene and dienophile. Our results oppose the widely accepted view that LAs catalyze the Diels–Alder reaction by enhancing the donor–acceptor [HOMOdiene–LUMOdienophile] interaction and constitute a novel physical mechanism for this indispensable textbook organic reaction. 相似文献
5.
Barry M. Trost Subham Mahapatra Martin Hansen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(20):6130-6134
A new mode of activation of an imine via a rare aza‐substituted π‐allyl complex is described. Palladium‐catalyzed C(sp3) H activation of the N‐allyl imine and the subsequent nucleophilic attack by the α‐alkyl cyanoester produced the 1‐aza‐1,3‐diene as the sole regioisomer. In contrast, nucleophilic attack by the α‐aryl cyanoester exclusively delivered the 2‐aza‐1,3‐diene, which was employed in an inverse‐electron‐demand Diels–Alder reaction for heterobiaryl synthesis. 相似文献
6.
Jianguang Han Xia Li Yong Guan Wenjun Zhao Prof. Dr. William D. Wulff Prof. Dr. Xiaoguang Lei 《Angewandte Chemie (International ed. in English)》2014,53(35):9257-9261
The first enantioselective total syntheses of prenylflavonoid Diels–Alder natural products (?)‐kuwanon I, (+)‐kuwanon J, (?)‐brosimone A, and (?)‐brosimone B have been accomplished from a common intermediate based on a concise synthetic strategy. Key elements of the synthesis include a biosynthesis‐inspired asymmetric Diels–Alder cycloaddition mediated by a chiral ligand/boron Lewis acid, as well as a process involving regioselective Schenck ene reaction, reduction, and dehydration to realize a biomimetic dehydrogenation for generation of the required diene precursor. Furthermore, a remarkable tandem inter‐/intramolecular asymmetric Diels–Alder cycloaddition process was applied for the synthesis of (?)‐brosimone A. 相似文献
7.
The Molecular Structure of gauche‐1,3‐Butadiene: Experimental Establishment of Non‐planarity
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)
Dr. Joshua H. Baraban Dr. Marie‐Aline Martin‐Drumel P. Bryan Changala Dr. Sandra Eibenberger Dr. Matthew Nava Prof. David Patterson Prof. John F. Stanton Prof. G. Barney Ellison Dr. Michael C. McCarthy 《Angewandte Chemie (International ed. in English)》2018,57(7):1821-1825
The planarity of the second stable conformer of 1,3‐butadiene, the archetypal diene for the Diels–Alder reaction in which a planar conjugated diene and a dienophile combine to form a ring, is not established. The most recent high level calculations predicted the species to adopt a twisted, gauche structure owing to steric interactions between the inner terminal hydrogens rather than a planar, cis structure favored by the conjugation of the double bonds. The structure cis‐1,3‐butadiene is unambiguously confirmed experimentally to indeed be gauche with a substantial dihedral angle of 34°, in excellent agreement with theory. Observation of two tunneling components indicates that the molecule undergoes facile interconversion between two equivalent enantiomeric forms. Comparison of experimentally determined structures for gauche‐ and trans‐butadiene provides an opportunity to examine the effects of conjugation and steric interactions. 相似文献
8.
A cationic palladium complex, [Pd(PPh3)2(MeCN)2](BF4)2, catalyzed the carbonylation of 2,3‐dien‐1‐ols under mild conditions. The dienols bearing two or more alkyl substituents on the diene part afforded 1,3‐diene‐2‐carboxylic acids successfully in tetrahydrofuran (THF), while those possessing one or no alkyl substituent gave polymers of the products exclusively. The former afforded the corresponding methyl esters in good yields when the reactions were carried out in methanol, while the latter afforded mainly the Diels–Alder reaction products of the resulting esters. An alkylidene group‐substituted π‐allylpalladium species has been presumed to be an intermediate. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
9.
Siu Min Tan Dr. Anthony C. Willis Prof. Michael N. Paddon‐Row Prof. Michael S. Sherburn 《Angewandte Chemie (International ed. in English)》2016,55(9):3081-3085
1‐Aminodecalins were prepared from acyclic precursors by combining the powerful twofold diene‐transmissive Diels–Alder chemistry of [3]dendralenes with the simplicity of enamine formation. On mixing at ambient temperature, a simple dienal condenses with a primary or secondary amine to generate the enamine, a 1‐amino‐[3]dendralene in situ, and this participates as a double diene in a sequence of two Diels–Alder events with separate dienophiles. Overall, four C?C bonds and one C?N bond are formed. Mechanistic insights into these reactions are provided by means of density functional theory calculations. 相似文献
10.
Salomé Llabrés Dr. Esther Vicente‐García Dr. Sara Preciado Cristina Guiu Prof. Ramon Pouplana Prof. Rodolfo Lavilla Prof. F. Javier Luque 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13355-13361
The evolution of a ternary molecular system (imine, diene and nitrile) is analyzed to disclose the pathways leading to a divergent synthetic outcome. The Lewis acid catalyzed reaction between cyclohexadiene, 2‐phenyl‐indol‐3‐one and acetonitrile yields the imino‐Diels–Alder adduct as the major product together with minor amounts of the Mannich–Ritter‐amidine product. The experimental and computational data show that the relative orientation of the initial reactants dictates the synthetic outcome. The exo approach between imine and diene leads to the Diels–Alder adduct in a concerted process, whereas the endo mode leads to a polarized intermediate, which is trapped by acetonitrile to yield the multicomponent adduct. 相似文献
11.
Stereoselective Synthesis of Polycycles Containing an Aziridine Group: Intramolecular aza‐Diels–Alder Reactions of Unactivated 2H‐Azirines with Unactivated Dienes
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)
Dr. Hua‐Dong Xu Hao Zhou Ying‐Peng Pan Xin‐Tao Ren Hao Wu Mei Han Run‐Ze Han Dr. Mei‐Hua Shen 《Angewandte Chemie (International ed. in English)》2016,55(7):2540-2544
Vinyl azide with a pendent diene can undergo thermal decomposition to a related azirine intermediate, which was used immediately in an intramolecular aza‐Diels–Alder reaction to furnish an aziridine‐containing trans‐fused tricyclic core structure with excellent stereoselectivity. The method provides a facile entry to complex polycyclic alkaliods which can be further elaborated by ring‐opening reactions and ring expansion of the aziridine moiety, as well as by dihydroxylation of the alkene group. 相似文献
12.
Andre H. St.Amant Fengying Huang Jia Lin Keith Rickert Vaheh Oganesyan Daniel Lemen Shenlan Mao Jay Harper Marcello Marelli Herren Wu Changshou Gao Javier ReaddeAlaniz R. James Christie 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(25):8577-8581
Here, we describe a diene‐containing noncanonical amino acid (ncAA) capable of undergoing fast and selective normal electron‐demand Diels–Alder (DA) reactions following its incorporation into antibodies. A cyclopentadiene derivative of lysine (CpHK) served as the reactive handle for DA transformations and the substrate for genetic incorporation. CpHK incorporated into antibodies with high efficiency and was available for maleimide conjugation or self‐reaction depending on position in the amino acid sequence. CpHK at position K274 reacted with the maleimide drug‐linker AZ1508 at a rate of ≈79 m ?1 s?1 to produce functional antibody–drug conjugates (ADCs) in a one‐step process. Incorporation of CpHK at position S239 resulted in dimerization, which covalently linked antibody heavy chains together. The diene ncAA described here is capable of producing therapeutic protein conjugates with clinically validated and widely available maleimide compounds, while also enabling proximity‐based stapling through a DA dimerization reaction. 相似文献
13.
Hyungwoo Kim Taejin Choi Min Chul Cha Ji Young Chang 《Journal of polymer science. Part A, Polymer chemistry》2013,51(17):3646-3653
A microporous polymer is prepared by a catalyst‐free Diels–Alder reaction. A cyclopentadiene with both a diene and a dienophile functionality and a dienophilic maleimide are used for the Diels–Alder reaction. 1,3,5‐Tris(bromomethyl)‐2,4,6‐trimethylbenzene is reacted with sodium cyclopentadienide to produce the multicyclopentadiene‐functionalized monomer. A crosslinked polymer ( CDAP ) is obtained by the reaction of the cyclopentadiene monomer with N,N′‐1,4‐phenylenedimaleimide. The thermal dissociation of the cyclopentadiene dimeric unit and the subsequent Diels–Alder reaction with the maleimide group are investigated by the model reaction. We are able to restructure the crosslinked polymer network by taking advantage of the thermal reversibility of the Diels–Alder linkage. After the post thermal treatment, the BET surface area of the polymer ( CDAP‐T ) is greatly increased from 317 to 1038 m2 g?1. CDAP‐T is functionalized with pyrene by bromination with N‐bromosuccinimide and the subsequent substitution reaction with aminopyrene. The adsorption property of the pyrene‐functionalized polymer for an aromatic dye is investigated using malachite green. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3646–3653 相似文献
14.
Yusuke Kumatabara Shiho Kaneko Satoshi Nakata Prof. Dr. Seiji Shirakawa Prof. Dr. Keiji Maruoka 《化学:亚洲杂志》2016,11(15):2126-2129
A piperidine‐derived tetraalkylammonium salt with a non‐coordinating counteranion worked as an effective hydrogen‐bonding catalyst in an aza‐Diels–Alder reaction of imines and a Danishefsky diene. The hydrogen‐bonding interaction between the ammonium salt and an imine was observed as part of a 1H NMR titration study. 相似文献
15.
Xiao Xiao Dr. Brian P. Woods Wen Xiu Prof. Thomas R. Hoye 《Angewandte Chemie (International ed. in English)》2018,57(31):9901-9905
The reaction of an aryne with an alkyne to generate a benzocyclobutadiene (BCB) intermediate is rare. We report here examples of this reaction, revealed by Diels–Alder trapping of the BCB by either pendant or external electron‐deficient alkynes. Mechanistic delineation of the reaction course is supported by DFT calculations. A three‐component process joining the benzyne first with an electron‐rich and then with an electron‐poor alkyne was uncovered. Reactions in which the BCB functions in a rarely observed role as a 4π diene component in Diels–Alder reactions are reported. The results also shed new light on aspects of the hexadehydro‐Diels–Alder reaction used to generate the benzynes. 相似文献
16.
Radical copolymerization of N‐phenylmaleimide and diene monomers in competition with diels–alder reaction
下载免费PDF全文
![点击此处可从《Journal of polymer science. Part A, Polymer chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Akikazu Matsumoto Daisuke Yamamoto 《Journal of polymer science. Part A, Polymer chemistry》2016,54(22):3616-3625
Radical copolymerization of N‐phenylmaleimide (PhMI) is carried out with various diene monomers including naturally occurring compounds and the copolymers are efficiently produced by the suppression of Diels–Alder reaction as the competitive side reaction. Diene monomers with an exomethylene moiety and a fixed s‐trans diene structure, such as 3‐methylenecyclopentene and 4‐isopropyl‐1‐methyl‐3‐methylenecyclohexene, exhibit high copolymerization reactivity to produce a high‐molecular‐weight copolymer in a high yield. The copolymerization of sterically hindered noncyclic diene monomers, such as 2,4‐dimethyl‐1,3‐pentadiene and 2,4‐hexadiene, also results in the formation of a high‐molecular‐weight copolymer in a moderate yield. The NMR spectroscopy reveals that the obtained copolymers consist of predominant 1,4‐repeating structures for the corresponding diene unit. The copolymers have excellent thermal stability, that is, an onset temperature of decomposition over 330 °C and a glass transition temperature over 130 °C. The copolymerization reactivity of these diene monomers is discussed based on the results of the DFT calculations. The efficient copolymer formation in competition with Diels–Alder addition is investigated under various conditions of the temperature, solvents, and initiators used for the copolymerization. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3616–3625. 相似文献
17.
Catalytic Asymmetric Diels–Alder Reaction of Quinone Imine Ketals: A Site‐Divergent Approach
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)
Dr. Takuya Hashimoto Hiroki Nakatsu Prof.Dr. Keiji Maruoka 《Angewandte Chemie (International ed. in English)》2015,54(15):4617-4621
The catalytic asymmetric Diels–Alder reaction of quinone imine ketals with diene carbamates catalyzed by axially chiral dicarboxylic acids is reported herein. A variety of primary and secondary alkyl‐substituted quinone derivatives which have not been applied in previous asymmetric quinone Diels–Alder reactions could be employed using this method. More importantly, we succeeded in developing a strategy to divert the reaction site in unsymmetrical 3‐alkyl quinone imine ketals from the inherently favored unsubstituted C?C bond to the disfavored alkyl‐substituted C?C bond. 相似文献
18.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(25):7272-7276
A versatile π‐extension reaction was developed based on the three‐component cross‐coupling of aryl halides, 2‐haloarylcarboxylic acids, and norbornadiene. The transformation is driven by the direction and subsequent decarboxylation of the carboxyl group, while norbornadiene serves as an ortho ‐C−H activator and ethylene synthon via a retro‐Diels–Alder reaction. Comprehensive DFT calculations were performed to account for the catalytic intermediates. 相似文献
19.
Development of an Enyne Metathesis/Isomerization/Diels–Alder One‐Pot Reaction for the Synthesis of a Novel Near‐Infrared (NIR) Dye Core
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Kohei Yamashita Yuki Fujii Shohei Yoshioka Dr. Hiroshi Aoyama Dr. Hirofumi Tsujino Prof. Dr. Tadayuki Uno Prof. Dr. Hiromichi Fujioka Dr. Mitsuhiro Arisawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17491-17494
N‐Alkyl‐N‐allyl‐2‐alkynylaniline derivatives undergo a tandem ring‐closing enyne metathesis/isomerization/Diels–Alder cycloaddition sequence in the presence of a second‐generation Grubbs catalyst and dienophiles. In practice, the acyclic enyne in the presence of the ruthenium alkylidene first undergoes ring‐closing metathesis to generate cyclic 4‐vinyl‐1,2‐dihydroquinolines; following diene isomerization and then the addition of a dienophile, these ring‐closing metathesis products are selectively converted into a 7‐methyl‐4H‐naphtho[3,2,1‐de]quinoline‐8,11‐dione core. Overall, the reaction sequence converts simple aniline derivatives into π‐conjugated small molecules, which have characteristic absorption in the near‐infrared region, in a single operation through three unique ruthenium‐catalyzed transformations. 相似文献
20.
Ayyagari V. Subrahmanyam Dr. Kalanidhi Palanichamy Krishna P. Kaliappan Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(28):8545-8556
An efficient approach for the synthesis of a variety of C‐aryl and spiro‐C‐aryl glycosides is described. This diversity‐oriented strategy employed here relies on a sequential enyne metathesis to generate the 1,3‐diene moiety and Diels–Alder reaction with different dienophiles followed by aromatisation. Whereas cross‐enyne metathesis with ethylene gas is used to install the 1,3‐diene moiety at the anomeric centre for the synthesis of C‐aryl glycosides, an intramolecular enyne metathesis on the sugar enyne is performed to generate the 1,3‐diene moiety for the synthesis of spiro‐C‐aryl glycosides. Efforts to extend this strategy to the synthesis of the core structure of natural C‐aryl glycoside gilvocarcin are also described. A combination of both C‐aryl and spiro‐C‐aryl glycosides in the same moiety to combine the features thereof has also been accomplished. A tandem enyne metathesis/Diels–Alder reaction/aromatisation has also been attempted to directly access the C‐aryl glycosides in one pot albeit in low yield. 相似文献