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1.
Mechanism of Ligand‐Controlled Regioselectivity‐Switchable Copper‐Catalyzed Alkylboration of Alkenes
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Zheng‐Yang Xu Yuan‐Ye Jiang Wei Su Prof. Dr. Hai‐Zhu Yu Prof. Dr. Yao Fu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(41):14611-14617
Cu‐catalyzed alkylboration of alkenes with bis(pinacolato)diboron ((Bpin)2) and alkyl halides provides a ligand‐controlled regioselectivity‐switchable method for the construction of complex boron‐containing compounds. Here, we employed DFT methods to elucidate the mechanistic details of this reaction and the origin of the different regioselectivity induced by Xantphos and Cy‐Xantphos. The calculation results reveal that the catalytic cycle mainly proceeds through the migratory insertion of alkenes on Cu‐Bpin complex, the oxidative addition of alkyl halides, and the reductive elimination of a C?C bond. Meanwhile, the rate‐ determining step is the oxidative addition of alkyl halides and the regioselectivity‐determining step is the migratory insertion of alkenes. The bulky cyclohexyl group of Cy‐Xantphos facilitates the approach of the substituents of alkenes to Bpin in the migratory insertion step and thus leads to the Markovnikov products. The less bulky phenyl group on Xantphos prefers keeping the substituents of alkenes away from the Bpin moiety in the migratory insertion step and thus results in anti‐Markovnikov products. 相似文献
2.
The Origin of Anti‐Markovnikov Regioselectivity in Alkene Hydroamination Reactions Catalyzed by [Rh(DPEphos)]+
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Almudena Couce‐Rios Prof. Dr. Agustí Lledós Dr. Gregori Ujaque 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9311-9320
The development of regioselective anti‐Markovnikov alkene's hydroamination is a long‐standing goal in catalysis. The [Rh(COD)(DPEphos)]+ complex is the most general and regioselective group 9 catalyst for such a process. The reaction mechanism for intermolecular hydroamination of alkenes catalyzed by [Rh(DPEphos)]+ complex is analyzed by means of DFT calculations. Hydroamination (alkene vs. amine activation routes) as well as oxidative amination pathways are analyzed. According to the computational results the operating mechanism can be generally described by alkene coordination, amine nucleophilic addition, proton transfer through the metal center and reductive elimination steps. The mechanism for the formation of the oxidative amination side product goes via a β‐elimination after the nucleophilic addition and metal center protonation steps. The origin of the regioselectivity for the addition process (Markovnikov vs. anti‐Markovnikov additions) is shown to be not charge but orbitally driven. Remarkably, η2 to η1 slippage degree on the alkene coordination mode is directly related to the regioselective outcome. 相似文献
3.
Jacob C. Timmerman Bradley D. Robertson Prof. Ross A. Widenhoefer 《Angewandte Chemie (International ed. in English)》2015,54(7):2251-2254
The cationic gold phosphine complex [{PCy2(o‐biphenyl)}Au(NCMe)]+SbF6? (Cy=cyclohexyl) catalyzes the intermolecular, anti‐Markovnikov hydroamination reaction of monosubstituted and cis‐ and trans‐disubstituted alkylidenecyclopropanes (ACPs) with imidazolidin‐2‐ones and other nucleophiles. This reaction forms 1‐cyclopropyl alkylamine derivatives in high yield and with high regio‐ and diastereoselectivity. NMR spectroscopic analysis of gold π‐ACP complexes and control experiments point to the sp hybridization of the ACP internal alkene carbon atom as controlling the regiochemistry of the ACP hydroamination reaction. 相似文献
4.
Dr. Chih‐Ming Chou Dr. Joyram Guin Dr. Christian Mück‐Lichtenfeld Prof. Dr. Stefan Grimme Prof. Dr. Armido Studer 《化学:亚洲杂志》2011,6(5):1197-1209
An efficient synthesis of N‐phthalimidyl, benzamidyl, acetamidyl, carbamoyl, and ureayl derivatives of dihydropyridines and the application of these reagents as precursors for N‐centered radicals are presented. These aminated dihydropyridines could be used in radical‐transfer hydroamination reactions of various electron‐rich as well as nonactivated olefins in the presence of thiols as polarity‐reversal catalysts. These reactions worked without the aid of any transition metal. Steric and electronic effects exerted by the N‐substitutents of the N‐centered radicals are discussed. In contrast to most metal‐catalyzed processes, the radical hydroamination delivered the opposite regioisomer with excellent anti‐Markovnikov selectivity. Hydroamination products were obtained as protected amines that are readily isolated. 相似文献
5.
Xiaoyong Du Dr. Yanlu Zhang Dr. Dongjie Peng Prof. Dr. Zheng Huang 《Angewandte Chemie (International ed. in English)》2016,55(23):6671-6675
A complementary set of base metal catalysts has been developed for regiodivergent alkene hydrosilylations: iron complexes of phosphine‐iminopyridine are selective for anti‐Markovnikov hydrosilylations (linear/branched up to >99:1), while the cobalt complexes bearing the same type of ligands provide an unprecedented high level of Markovnikov selectivity (branched/linear up to >99:1). Both systems exhibit high efficiency and wide functional group tolerance. 相似文献
6.
Copper‐Catalyzed Enantioselective Markovnikov Protoboration of α‐Olefins Enabled by a Buttressed N‐Heterocyclic Carbene Ligand
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Yuan Cai Xin‐Tuo Yang Dr. Shuo‐Qing Zhang Feng Li Yu‐Qing Li Lin‐Xin Ruan Prof. Dr. Xin Hong Prof. Dr. Shi‐Liang Shi 《Angewandte Chemie (International ed. in English)》2018,57(5):1376-1380
Reported is a highly enantioselective copper‐catalyzed Markovnikov protoboration of unactivated terminal alkenes. A variety of simple and abundant feedstock α‐olefins bearing a diverse array of functional groups and heterocyclic substituents can be used as substrates, and the reaction proceeds under mild reaction conditions at ambient temperature to provide expedient access to enantioenriched alkylboronic esters in good regioselectivity and with excellent enantiocontrol. Critical to the success of the protocol was the development and application of a novel, sterically hindered N‐heterocyclic carbene, (R,R,R,R)‐ANIPE, as the ligand for copper. 相似文献
7.
Yikun Zhang Sixue Wu Hongwei Shi 《Phosphorus, sulfur, and silicon and the related elements》2016,191(10):1324-1328
Using potassium iodide as a catalyst and m-chloroperbenzoic acid as an oxidant, an efficient catalytic procedure has been developed for the azidoselenenylation of alkenes with sodium azide and diselenides, and a series of corresponding β-azidoselenides, most of which are new compounds, have been prepared in moderate to good yields under mild reaction conditions. This in situ generation of the electrophilic selenenylating reagents with addition to alkenes is a stereospecific anti addition, which occurs with a Markovnikov orientation. 相似文献
8.
Boron Lewis Acid‐Catalyzed Hydroboration of Alkenes with Pinacolborane: BArF3 Does What B(C6F5)3 Cannot Do!
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Dr. Qin Yin Dr. Hendrik F. T. Klare Prof. Dr. Martin Oestreich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(39):13840-13844
The transition‐metal‐free hydroboration of various alkenes with pinacolborane (HBpin) initiated by tris[3,5‐bis(trifluoromethyl)phenyl]borane (BArF3) is reported. The choice of the boron Lewis acid is crucial as the more prominent boron Lewis acid tris(pentafluorophenyl)borane (B(C6F5)3) is reluctant to react. Unlike B(C6F5)3, BArF3 is found to engage in substituent redistribution with HBpin, resulting in the formation of ArFBpin and the electron‐deficient diboranes [H2BArF]2 and [(ArF)(H)B(μ‐H)2BArF2]. These in situ‐generated hydroboranes undergo regioselective hydroboration of styrene derivatives as well as aliphatic alkenes with cis diastereoselectivity. Another ligand metathesis of these adducts with HBpin subsequently affords the corresponding HBpin‐derived anti‐Markovnikov adducts. The reactive hydroboranes are regenerated in this step, thereby closing the catalytic cycle. 相似文献
9.
Stereoselective Synthesis of Trisubstituted Alkenes through Sequential Iron‐Catalyzed Reductive anti‐Carbozincation of Terminal Alkynes and Base‐Metal‐Catalyzed Negishi Cross‐Coupling
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Dr. Chi Wai Cheung Prof. Dr. Xile Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18439-18444
The stereoselective synthesis of trisubstituted alkenes is challenging. Here, we show that an iron‐catalyzed anti‐selective carbozincation of terminal alkynes can be combined with a base‐metal‐catalyzed cross‐coupling to prepare trisubstituted alkenes in a one‐pot reaction and with high regio‐ and stereocontrol. Cu‐, Ni‐, and Co‐based catalytic systems are developed for the coupling of sp‐, sp2‐, and sp3‐hybridized carbon electrophiles, respectively. The method encompasses a large substrate scope, as various alkynyl, aryl, alkenyl, acyl, and alkyl halides are suitable coupling partners. Compared with conventional carbometalation reactions of alkynes, the current method avoids pre‐made organometallic reagents and has a distinct stereoselectivity. 相似文献
10.
A Modified System for the Synthesis of Enantioenriched N‐Arylamines through Copper‐Catalyzed Hydroamination
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Saki Ichikawa Dr. Shaolin Zhu Prof. Dr. Stephen L. Buchwald 《Angewandte Chemie (International ed. in English)》2018,57(28):8714-8718
Despite significant recent progress in copper‐catalyzed enantioselective hydroamination chemistry, the synthesis of chiral N‐arylamines, which are frequently found in natural products and pharmaceuticals, has not been realized. Initial experiments with N‐arylhydroxylamine ester electrophiles were unsuccessful and, instead, their reduction in the presence of copper hydride (CuH) catalysts was observed. Herein, we report key modifications to our previously reported hydroamination methods that lead to broadly applicable conditions for the enantioselective net addition of secondary anilines across the double bond of styrenes, 1,1‐disubstituted olefins, and terminal alkenes. NMR studies suggest that suppression of the undesired reduction pathway is the basis for the dramatic improvements in yield under the reported method. 相似文献
11.
Enantiodivergent Synthesis of (+)‐ and (−)‐Pyrrolidine 197B: Synthesis of trans‐2,5‐Disubstituted Pyrrolidines by Intramolecular Hydroamination
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Dr. Sixto J. Pérez Dr. Martín A. Purino Daniel A. Cruz Juan M. López‐Soria Dr. Rubén M. Carballo Prof. Miguel A. Ramírez Dr. Israel Fernández Prof. Víctor S. Martín Dr. Juan I. Padrón 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(43):15529-15535
A highly efficient, diastereoselective, iron(III)‐catalyzed intramolecular hydroamination/cyclization reaction involving α‐substituted amino alkenes is described. Thus, enantiopure trans‐2,5‐disubstituted pyrrolidines and trans‐5‐substituted proline derivatives were synthesized by means of a combination of enantiopure starting materials, easily available from l ‐α‐amino acids, with sustainable metal catalysts such as iron(III) salts. The scope of this methodology is highlighted in an enantiodivergent approach to the synthesis of both (+)‐ and (?)‐pyrrolidine 197B alkaloids from l ‐glutamic acid. In addition, a computational study was carried out to gain insight into the complete diastereoselectivity of the transformation. 相似文献
12.
Prof. Dr. Pavel Kočovský Prof. Dr. Jan‐E. Bäckvall 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):36-56
In this review the stereochemistry of palladium‐catalyzed addition of nucleophiles to alkenes is discussed, and examples of these reactions in organic synthesis are given. Most of the reactions discussed involve oxygen and nitrogen nucleophiles; the Wacker oxidation of ethylene has been reviewed in detail. An anti‐hydroxypalladation in the Wacker oxidation has strong support from both experimental and computational studies. From the reviewed material it is clear that anti‐addition of oxygen and nitrogen nucleophiles is strongly favored in intermolecular addition to olefin–palladium complexes even if the nucleophile is coordinated to the metal. On the other hand, syn‐addition is common in the case of intramolecular oxy‐ and amidopalladation as a result of the initial coordination of the internal nucleophile to the metal. 相似文献
13.
Trissa Joseph G.V. Shanbhag D.P. Sawant S.B. Halligudi 《Journal of molecular catalysis. A, Chemical》2006,250(1-2):210-217
The catalytic activity of montmorillonite clays as a catalyst for the hydroamination of α,β-ethylenic compounds with amines was tested. Aniline and substituted anilines reacted with α,β-ethylenic compounds in the presence of catalytic amount of commercially available clay to afford exclusively anti-Markovnikov adduct in excellent yields. Aniline reacted with ethyl acrylate to yield only anti-Markovnikov adduct N-[2-(ethoxycarbonyl)ethyl]aniline (mono-addition product). No Markovnikov adduct (N-[1-(ethoxycarbonyl)ethyl]aniline and double addition product N,N-bis[2-(ethoxycarbonyl)ethyl]aniline were formed under selected reaction conditions. For a better exploitation of the catalytic activity in terms of increased activity and improved selectivity for the mono-addition product, the reaction parameters were optimized in terms of temperature, solvent, reactant mole ratio. Under optimized reaction conditions, montmorillonite clay K-10 showed a superior catalytic performance in the hydroamination of ethyl acrylate with aniline with a conversion of aniline to mono-addition product (almost 100% chemoselectivity) with a high rate constant 0.3414 min−1 compared to the reported protocols. The dependence of conversion of aniline over different types of montmorillonite clays (K-10, K-20, K-30, Al-Pillared clay and untreated clay) has also been discussed. The activities of clay for the hydroamination of different aromatic and aliphatic amines have also been investigated. Under harsh reaction conditions (increased temperature and long reaction time) small amounts of di-addition products were observed. The kinetics data has been interpreted using the initial rate approach model. 相似文献
14.
Revital Sasson 《Journal of fluorine chemistry》2006,127(7):962-965
A variety of alkenes and α,β-unsaturated carbonyls were reacted with BrF3 to form vicinal bromofluoro compounds. In most cases, the reactions followed a Markovnikov regioselectivity and anti-addition stereospecifity. They proceeded well even with deactivated olefins in around 70% yield. The bromofluoro compounds served as starting materials for the synthesis of fluoroalkenes and fluoroamines. 相似文献
15.
In the presence of NH4I as catalyst and m‐chloroperbenzoic acid as oxidant, the Se–Se bond cleavage of diselenides undergoes smoothly. The in situ generated reactive electrophilic Se species reacts with alkenes quickly, and a series of β‐hydroxy selenides are prepared in good yields. This new catalytic method for synthesis of β‐hydroxy selenides is a stereospecific anti addition, which occurs with a Markovnikov orientation. 相似文献
16.
Photoredox‐Catalyzed Stereoselective Conversion of Alkynes into Tetrasubstituted Trifluoromethylated Alkenes
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Ren Tomita Dr. Takashi Koike Prof. Dr. Munetaka Akita 《Angewandte Chemie (International ed. in English)》2015,54(44):12923-12927
A regio‐ and stereoselective synthesis of trifluoromethylated alkenes bearing four different substituents has been developed. Stereocontrolled sulfonyloxytrifluoromethylation of unsymmetric internal alkynes with an electrophilic CF3 reagent, namely the triflate salt of the Yagupol’skii–Umemoto reagent, in the presence of an Ir photoredox catalyst under visible‐light irradiation afforded trifluoromethylalkenyl triflates with well‐predictable stereochemistry resulting from anti addition of the trifluoromethyl and triflate groups. Subsequent palladium‐catalyzed cross‐couplings led to tetrasubstituted trifluoromethylated alkenes in a highly stereoselective manner. The present method is the first example of a facile one‐pot synthesis of tetrasubstituted trifluoromethylated alkenes from simple alkynes. 相似文献
17.
Edwin Alvarado Anna C. Badaj Timothy G. Larocque Prof. Dr. Gino G. Lavoie 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(38):12112-12121
Gold(I) complexes of 1‐[1‐(2,6‐dimethylphenylimino)alkyl]‐3‐(mesityl)imidazol‐2‐ylidene (C^ImineR), 1,3‐dimesitylimidazol‐2‐ylidene (IMes) and of the corresponding thione derivatives (S^ImineR and IMesS) were prepared and structurally characterised. The solid‐state structure of the C^ImineR and S^ImineR gold(I) complexes showed monodentate coordination of the ligand and a dangling imine group that could bind reversibly to the metal centre to stabilise otherwise unstable catalytic intermediates. Interestingly, reaction of C^IminetBu with [AuCl(SMe2)] led to the formation of [(C^IminetBu)AuCl], which rearranges upon crystallisation into the unusual complex cation [(C^IminetBu)2Au]+, with AuCl2? as the counterion. The activity of the gold complexes in the hydroamination of phenylacetylene with substituted anilines was tested and compared to control catalyst systems. The best catalytic performance was obtained with [(C^IminetBu)AuCl], with the exclusive formation of the Markovnikov addition product in excellent yield (>95 %) regardless of the substituents on aniline. 相似文献
18.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(38):11598-11602
A protocol for the anti‐Markovnikov hydrofunctionalization of alkenes has been developed by the use of a benzyl group as a traceless redox‐active hydrogen donor. Under copper catalysis and in the presence of CF3‐ or N3‐containing hypervalent iodine reagents, a series of homoallylic alcohol derivatives were hydrofunctionalized regioselectivity. A similar principle was also applied to the hydrofunctionalization of alkenols. 相似文献
19.
Enantioselective Synthesis of α‐Aminosilanes by Copper‐Catalyzed Hydroamination of Vinylsilanes
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Nootaree Niljianskul Dr. Shaolin Zhu Prof. Dr. Stephen L. Buchwald 《Angewandte Chemie (International ed. in English)》2015,54(5):1638-1641
The synthesis of α‐aminosilanes by a highly enantio‐ and regioselective copper‐catalyzed hydroamination of vinylsilanes is reported. The system employs Cu‐DTBM‐SEGPHOS as the catalyst, diethoxymethylsilane as the stoichiometric reductant, and O‐benzoylhydroxylamines as the electrophilic nitrogen source. This hydroamination reaction is compatible with differentially substituted vinylsilanes, thus providing access to amino acid mimics and other valuable chiral organosilicon compounds. 相似文献
20.
Gold‐Catalyzed Reaction of ortho‐Alkynylarylaldehydes with Conjugated Dienes: An Efficient Access to Highly Strained Tetracyclic Bridgehead Olefins
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Dr. Ziping Cao Hongbo Zhu Dr. Xin Meng Laijin Tian Xuejun Sun Guang Chen Prof. Jinmao You 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9125-9129
An unprecedented access to strained tetracyclic bridgehead alkenes by reaction of easily accessible ortho‐alkynylarylaldehydes with conjugated dienes is described. The process involves a chemo‐ and stereo‐selective, gold‐catalyzed, tandem intermolecular [3+2] cycloaddition/Prins‐type ring‐closing reaction that allows generating structural complexity in a straightforward manner. This approach for the preparation of anti‐Bredt compounds is synthetically superior to those previously reported: the procedure is easy to implement, operates under mild experimental conditions, is efficient, and exhibits a good substrate scope. 相似文献