- Visible Light Induced Br?nsted Acid Assisted Pd-Catalyzed Alkyl Heck Reaction of Diazo Compounds and N-Tosylhydrazones
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A mild visible light-induced palladium-catalyzed alkyl Heck reaction of diazo compounds and N-tosylhydrazones is reported. A broad range of vinyl arenes and heteroarenes with high functional group tolerance, as well as a range of different diazo compounds, can efficiently undergo this transformation. This method features Br?nsted acid-assisted generation of hybrid palladium C(sp3)-centered radical intermediate, which allowed for new selective C?H functionalization protocol.
- Dubrovina, Anastasiia,Gevorgyan, Vladimir,Kvasovs, Nikita,Zhang, Ziyan
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supporting information
(2021/11/30)
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- METHOD FOR OXIDATIVE CLEAVAGE OF COMPOUNDS WITH UNSATURATED DOUBLE BOND
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A method for oxidative cleavage of a compound with an unsaturated double bond is provided. The method includes the steps of: (A) providing a compound (I) with an unsaturated double bond, a trifluoromethyl-containing reagent, and a catalyst; wherein, the catalyst is represented by Formula (II): M(O)mL1yL2z??(II);wherein, M, L1, L2, m, y, z, R1, R2 and R3 are defined in the specification; and(B) mixing the compound with an unsaturated double bond and the trifluoromethyl-containing reagent to perform an oxidative cleavage of the compound with the unsaturated double bond by using the catalyst in air or under oxygen atmosphere condition to obtain a compound represented by Formula (III):
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Paragraph 0027-0029
(2021/07/10)
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- Method for oxidative cracking of compound containing unsaturated double bonds
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The invention relates to a method for oxidative cracking of a compound containing unsaturated double bonds. The method comprises the following steps: (A) providing a compound (I) containing unsaturated double bonds, a trifluoromethyl-containing reagent and a catalyst, wherein the catalyst is shown as a formula (II): M(O)mL1yL2z (II), M, L1, L2, m, y, z, R1, R2 and R3 being defined in the specification; and (B) mixing the compound containing the unsaturated double bonds and the trifluoromethyl-containing reagent, and performing an oxidative cracking reaction on the compound containing the unsaturated double bonds in the presence of air or oxygen by using the catalyst to obtain a compound represented by formula (III),.
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Paragraph 0038-0043; 0068-0070
(2021/07/09)
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- METHOD FOR OXIDATIVE CLEAVAGE OF COMPOUNDS WITH UNSATURATED DOUBLE BOND
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A method for oxidative cleavage of a compound with an unsaturated double bond is provided. The method comprises the following step: (A) providing a compound (I) with an unsaturated double bond, a reagent with trifluoromethyl, and a catalyst; wherein the catalyst is represented by the following formula (II): M(O)mL1yL2z (II); wherein, M, L1, L2, m, y, z, R1, R2 and R3 are defined in the specification; and (B) mixing the compound with an unsaturated double bond and the reagent with a trifluoromethyl to perform an oxidation of the compound with the unsaturated double bond by using the catalyst at air or an oxygen condition to get a compound presented as formula (III):
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Paragraph 0024-0025; 0034
(2021/03/19)
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- Regioselective Three-Component Synthesis of Vicinal Diamines via 1,2-Diamination of Styrenes
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The vicinal diamine motif plays a significant role in natural products, drug design, and organic synthesis, and development of synthetic methods for the synthesis of diamines is a long-standing interest. Herein, we report a regioselective intermolecular three-component vicinal diamination of styrenes with acetonitrile and azodicarboxylates. The diamination products can be produced in moderate to excellent yields via the Ritter reaction. Synthetic applications and theoretical studies of this reaction have been conducted.
- Cao, Jie,Lv, Daqi,Yu, Fei,Chiou, Mong-Feng,Li, Yajun,Bao, Hongli
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supporting information
p. 3184 - 3189
(2021/05/05)
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- Catalyst-Free Visible-Light-Mediated Iodoamination of Olefins and Synthetic Applications
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Herein we report a catalyst- and metal-free visible-light-mediated protocol enabling the iodoamination of miscellaneous olefins. This protocol is characterized by high yields under environmentally benign reaction conditions utilizing commercially available substrates and a green and biodegradable solvent. Furthermore, the protocol allows for late-stage functionalization of bioactive molecules and can be scaled to gram quantities of product, which offers manifold possibilities for further transformations, including morpholine, piperidine, pyrrolidine, and aziridine synthesis.
- Engl, Sebastian,Reiser, Oliver
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supporting information
p. 5581 - 5586
(2021/07/26)
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- B(C6F5)3-Catalyzed Diastereoselective Formal (4 + 1)-Cycloaddition of Vinylcyclopropanes and Et2SiH2
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A formal (4 + 1)-cycloaddition of vinylcyclopropanes and Et2SiH2 to afford 3,4-disubstituted silolanes is reported. The reaction sequence commences with the known B(C6F5)3-catalyzed alkene hydrosilylation with dihydrosilanes. Cleavage of the remaining Si-H bond in the hydrosilylation product assisted by B(C6F5)3 leads to formation of a cyclopropane-stabilized silylium ion. The activated cyclopropane ring is then opened by the in situ-generated borohydride accompanied by ring closure to the silolane. The diastereoselectivity is rationalized by a mechanistic model.
- Long, Peng-Wei,Oestreich, Martin
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supporting information
p. 4834 - 4837
(2021/06/28)
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- Photoinduced [3+2] Annulation of Alkene with o-Iodoanilines: An Expedient Approach to Indolines
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A highly regioselective [3+2] cyclization of alkenes with 2-iodoanilines under the irradiation of UV light is described. This general, metal-free strategy facilitates the direct preparation of 2-mono-/disubstituted indolines as well as spiroindolines through alkene carboamination in one step. Mechanistic studies suggested that the photochemical protocol proceeded via a radical pathway.
- Zhao, Xinxin,Guo, Lin,Yang, Chao,Xia, Wujiong
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supporting information
p. 1341 - 1348
(2020/11/19)
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- Visible-Light-Induced Meerwein Fluoroarylation of Styrenes
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An unprecedented approach for assembling a broad range of 1,2-diarylethane derivatives with fluorine-containing fully substituted carbon centers was developed. The protocol features straightforward operation, proceeds under metal-free condition, and accommodates a large variety of synthetically useful functionalities. The critical aspect to the success of this novel transformation lies in using aryldiazonium salts as both aryl radical progenitor and also as single electron acceptor which elegantly enables a radical-polar crossover manifold.
- Tang, Hai-Jun,Zhang, Bin,Xue, Fei,Feng, Chao
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supporting information
p. 4040 - 4044
(2021/05/26)
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- Electrochemical fluorosulfonylation of styrenes
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An environmentally friendly and efficient electrochemical fluorosulfonylation of styrenes has been developed. With the use of sulfonylhydrazides and triethylamine trihydrofluoride, a diverse array of β-fluorosulfones could be readily obtained. This reaction features mild conditions and a broad substrate scope, which could also be conveniently extended to a gram-scale preparation.
- Jiang, Yi-Min,Wu, Shao-Fen,Yan, Hong,Ye, Ke-Yin,Yu, Yi,Yuan, Yaofeng
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supporting information
p. 11481 - 11484
(2021/11/16)
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- Electrochemistry enabled selective vicinal fluorosulfenylation and fluorosulfoxidation of alkenes
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Both sulfur and fluorine play important roles in organic synthesis, the life science, and materials science. The direct incorporation of these elements into organic scaffolds with precise control of the oxidation states of sulfur moieties is of great significance. Herein, we report the highly selective electrochemical vicinal fluorosulfenylation and fluorosulfoxidation reactions of alkenes, which were enabled by the unique ability of electrochemistry to dial in the potentials on demand. Preliminary mechanistic investigations revealed that the fluorosulfenylation reaction proceeded through a radical-polar crossover mechanism involving a key episulfonium ion intermediate. Subsequent electrochemical oxidation of fluorosulfides to fluorosulfoxides were readily achieved under a higher applied potential with the adventitious H2O in the reaction mixture.
- Jiang, Yimin,Shi, Zhaojiang,Wu, Jinnan,Wu, Shaofen,Ye, Keyin,Yu, Yi,Yuan, Yaofeng
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supporting information
(2021/11/17)
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- Base-Mediated Site-Selective Hydroamination of Alkenes
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We present a base-mediated hydroamination protocol, using substoichiometric amounts of a hydrosilane and potassium tertbutoxide, that operates under mild conditions at 30 °C. Many aryl- and heteroatom-substituted olefins as well as arylamines are tolerated, affording the desired products with complete regioselectivity. Preliminary mechanistic investigations reveal a non-radical pathway for hydroamination. A sequential remote hydroamination strategy involving an initial Fe-catalysed olefin isomerisation followed by our base-mediated hydroamination was also developed to directly access-arylamines from terminal aliphatic alkenes.
- Koh, Ming Joo,Lee, Boon Chong,Li, Ping,Zhang, Xiaoxiang
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supporting information
(2021/12/29)
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- Additions of Aldehyde-Derived Radicals and Nucleophilic N-Alkylindoles to Styrenes by Photoredox Catalysis
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The consecutive addition of acyl radicals and N-alkylindole nucleophiles to styrenes was established, as well as some additional radical-nucleophile combinations. Both aryl and aliphatic aldehydes give reasonable yields. The reaction proceeds best for α-substituted styrenes, effectively creating a quaternary all-carbon center. Some iridium-based photoredox systems are catalytically active; furthermore, a base is needed in this transformation. Radicals are formed by reductive perester cleavage and hydrogen atom transfer.
- Klussmann, Martin,Lux, Marcel
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supporting information
(2020/04/30)
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- Silylium-Ion-Promoted (5+1) Cycloaddition of Aryl-Substituted Vinylcyclopropanes and Hydrosilanes Involving Aryl Migration
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A transition-metal-free (5+1) cycloaddition of aryl-substituted vinylcyclopropanes (VCPs) and hydrosilanes to afford silacyclohexanes is reported. Catalytic amounts of the trityl cation initiate the reaction by hydride abstraction from the hydrosilane, and further progress of the reaction is maintained by self-regeneration of the silylium ions. The new reaction involves a [1,2] migration of an aryl group, eventually furnishing 4- rather than 3-aryl-substituted silacyclohexane derivatives as major products. Various control experiments and quantum-chemical calculations support a mechanistic picture where a silylium ion intramolecularly stabilized by a cyclopropane ring can either undergo a kinetically favored concerted [1,2] aryl migration/ring expansion or engage in a cyclopropane-to-cyclopropane rearrangement.
- Bonetti, Vittorio,He, Tao,Klare, Hendrik F. T.,Oestreich, Martin,Wang, Guoqiang
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supporting information
p. 12186 - 12191
(2020/05/22)
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- B(C6F5)3-Catalyzed Hydrosilylation of Vinylcyclopropanes
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A hydrosilylation of vinylcyclopropanes (VCPs) catalyzed by the strong boron Lewis acid B(C6F5)3 is reported. For the majority of VCPs, little or no ring opening of the cyclopropyl unit is observed. Conversely, for VCPs with bulky R groups, such as ortho-substituted aryl rings or branched alkyl residues, ring opening is the exclusive reaction pathway. This finding is explained by the thwarted hydride delivery to a sterically shielded, β-silicon-stabilized cyclopropylcarbinyl cation intermediate.
- He, Tao,Long, Peng-Wei,Oestreich, Martin
-
supporting information
p. 7383 - 7386
(2020/10/12)
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- Harnessing Applied Potential: Selective β-Hydrocarboxylation of Substituted Olefins
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The construction of carboxylic acid compounds in a selective fashion from low value materials such as alkenes remains a long-standing challenge to synthetic chemists. In particular, β-addition to styrenes is underdeveloped. Herein we report a new electrosynthetic approach to the selective hydrocarboxylation of alkenes that overcomes the limitations of current transition metal and photochemical approaches. The reported method allows unprecedented direct access to carboxylic acids derived from β,β-trisubstituted alkenes, in a highly regioselective manner.
- Alkayal, Anas,Buckley, Benjamin R.,Malkov, Andrei V.,Montanaro, Stephanie,Tabas, Volodymyr,Wright, Iain A.
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supporting information
(2020/02/13)
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- Enantioselective Radical-Polar Crossover Reactions of Indanonecarboxamides with Alkenes
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Highly efficient asymmetric intermolecular radical-polar crossover reactions were realized by combining a chiral N,N′-dioxide/NiII complex catalyst with Ag2O under mild reaction conditions. Various terminal alkenes and indanonecarboxamides/esters underwent radical addition/cyclization reactions to afford spiro-iminolactones and spirolactones with good to excellent yields (up to 99 %) and enantioselectivities (up to 97 % ee). Furthermore, a range of different radical-mediated oxidation/elimination or epoxide ring-opening products were obtained under mild reaction conditions. The Lewis acid catalysts exhibited excellent performance and precluded the strong background reaction.
- Cao, Weidi,Feng, Xiaoming,Liu, Xiaohua,Wu, Wangbin,Xu, Xi,Yu, Han,Zhang, Xiying
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supporting information
p. 4846 - 4850
(2020/02/11)
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- Fe-Catalyzed Reductive Couplings of Terminal (Hetero)Aryl Alkenes and Alkyl Halides under Aqueous Micellar Conditions
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The combination of a vinyl-substituted aromatic or heteroaromatic and an alkyl bromide or iodide leads, in the presence of Zn and a catalytic amount of an Fe(II) salt, to a net reductive coupling. The new C-C bond is regiospecifically formed at rt at the β-site of the alkene. The coupling only occurs in an aqueous micellar medium, where a radical process is likely, supported by several control experiments. A mechanism based on these data is proposed.
- Pang, Haobo,Wang, Ye,Gallou, Fabrice,Lipshutz, Bruce H.
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supporting information
p. 17117 - 17124
(2019/11/03)
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- Light-Enabled Enantiodivergence: Stereospecific Reduction of Activated Alkenes Using a Single Organocatalyst Enantiomer
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Light-enabled enantiodivergence is demonstrated in which the alkene substrate configuration is manipulated (E → Z) prior to organocatalytic reduction with a chiral thiourea and Hantzsch ester. This allows stereodivergent reduction to be regulated at the substrate level with high fidelity and mitigates the need for a second, enantiomeric catalyst (up to 93:07 and 95:5 er). The synthetic utility of this strategy has been demonstrated in the synthesis of the weight-loss drug (R)-Lorcaserin (Belviq) and a potent AMPA modulator.
- Hostmann, Theresa,Molloy, John J.,Bussmann, Kathrin,Gilmour, Ryan
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supporting information
p. 10164 - 10168
(2019/12/24)
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- Visible light-mediated intermolecular [2 + 2] photocycloaddition of 1-aryl-2-nitroethenes and olefins
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Despite the importance of cyclobutanes there are not many direct [2 + 2] photocycloaddition reactions which can be performed with visible light in the absence of a catalyst. A notable exception is the reaction of 1-aryl-2-nitroethenes and olefins which can be performed at a wavelength of λ = 419 nm or λ = 424 nm in CH2Cl2 as the solvent. In the present study, a total of 15 1-aryl-2-nitroethenes were found to undergo a [2 + 2] photocycloaddition with 2,3-dimethyl-2-butene (28-86% yield) and a set of 12 olefins was studied in their photocycloaddition to 1-phenyl-2-nitroethene (37-88% yield). All mechanistic results are in agreement with a triplet reaction pathway and with the intermediacy of a 1,4-diradical.
- Mohr, Lisa-Marie,Bauer, Andreas,Jandl, Christian,Bach, Thorsten
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supporting information
p. 7192 - 7203
(2019/08/07)
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- A convenient access to allylic triflones with allenes and triflyl chloride in the presence of (EtO)2P(O)H
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A simple method for the preparation of allylic triflones from allenes and triflyl chloride in the presence of (EtO)2P(O)H has been developed. The features of this reaction are catalyst-free and simple starting substrates. This method tolerates diverse functional groups and substituted allylic triflones are obtained in moderate to good yields.
- Ni, Jixiang,Jiang, Yong,An, Zhenyu,Lan, Jingfeng,Yan, Rulong
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supporting information
p. 7343 - 7345
(2019/06/27)
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- Ex Situ Formation of Methanethiol: Application in the Gold(I)-Promoted Anti-Markovnikov Hydrothiolation of Olefins
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A protocol for the Au-promoted anti-Markovnikov hydrothiolation of olefins using ex situ generated methanethiol is reported. The use of S-methylisothiourea hemisulfate salt as a solid precursor for methanethiol generation ensures a safe and reliable deliverance of a stoichiometric amount of this thiol. The procedure was shown to work for a broad range of olefins providing the corresponding hydrothiolated adduct in good to excellent yields. Mechanistic evaluations suggest that thiyl radicals are generated and that gold acts as an efficient but stable radical initiator.
- Kristensen, Steffan K.,Laursen, Simon L. R.,Taarning, Esben,Skrydstrup, Troels
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supporting information
p. 13887 - 13891
(2018/10/02)
-
- A Manganese Nanosheet: New Cluster Topology and Catalysis
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While the coordination chemistry of monometallic complexes and the surface characteristics of larger metal particles are well understood, preparations of molecular metallic nanoclusters remain a great challenge. Discrete planar metal clusters constitute nanoscale snapshots of cluster growth but are especially rare owing to the strong preference for three-dimensional structures and rapid aggregation or decomposition. A simple ligand-exchange procedure has led to the formation of a novel heteroleptic Mn6 nanocluster that crystallized in an unprecedented flat-chair topology and exhibited unique magnetic and catalytic properties. Magnetic susceptibility studies documented strong electronic communication between the manganese ions. Reductive activation of the molecular Mn6 cluster enabled catalytic hydrogenations of alkenes, alkynes, and imines.
- Chakraborty, Uttam,Reyes-Rodriguez, Efrain,Demeshko, Serhiy,Meyer, Franc,Jacobi von Wangelin, Axel
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supporting information
p. 4970 - 4975
(2018/03/28)
-
- Mn(OAc)3-Mediated Synthesis of 3-Phosphonyldihydrofurans from β-Ketophosphonates and Alkenes
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A new, general method for the synthesis of 3-phosphonyldihydrofuran derivatives has been achieved through Mn(OAc)3-mediated radical cyclization between β-ketophosphonates and alkenes. This transformation allows the direct formation of C-C/C-O bonds and the construction of a dihydrofuran ring in one reaction with operational simplicity and excellent functional-group compatibility.
- Lu, Guozhang,Lin, Binzhou,Gao, Yuzhen,Ying, Jianxi,Tang, Guo,Zhao, Yufen
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p. 724 - 728
(2017/03/21)
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- Copper/B2pin2-catalyzed C-H difluoroacetylation-cycloamidation of anilines leading to the formation of 3,3-difluoro-2-oxindoles
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An original and efficient synthesis of 3,3-difluoro-2-oxindole derivatives has been developed via copper/B2pin2-catalyzed difluoroacetylation of aniline via C-H activation followed by intramolecular amidation. In this method, amino groups in primary, secondary or tertiary anilines act as directing groups, providing ortho-difluoroacetylated products regioselectively. And in the first two cases, further intramolecular amidation affords 3,3-difluoro-2-oxindole derivatives via a one-pot strategy. This method facilitates the synthesis of compound A as a potent and selective EP3 receptor antagonist in only five steps in 13% yield instead of the previously reported nine steps in overall 4% yield.
- Ke, Miaolin,Song, Qiuling
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supporting information
p. 2222 - 2225
(2017/02/23)
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- Iron-catalyzed hydroboration of vinylcyclopropanes
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An iron-catalyzed hydroboration of vinylcyclo-propane with HBpin is first reported for the preparation of valuable homoallylic organoboronic esters. The iron catalysts enable efficient and regioselective C-C cleavage of vinyl-cyclopropanes, stereoselectively delivering E-alkenes with good stereospecific selectivity at an allylic position. This protocol exhibits mild conditions with good functional group tolerability. The chiral homoallylic organoboronic esters could be further converted into chiral polysubstituted tetrahydrofuran and tetrahydropyran.
- Chen, Chenhui,Shen, Xuzhong,Chen, Jianhui,Hong, Xin,Lu, Zhan
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supporting information
p. 5422 - 5425
(2017/11/06)
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- Alkene Hydrogenations by Soluble Iron Nanocluster Catalysts
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The replacement of noble metal technologies and the realization of new reactivities with earth-abundant metals is at the heart of sustainable synthesis. Alkene hydrogenations have so far been most effectively performed by noble metal catalysts. This study reports an iron-catalyzed hydrogenation protocol for tri- and tetra-substituted alkenes of unprecedented activity and scope under mild conditions (1–4 bar H2, 20 °C). Instructive snapshots at the interface of homogeneous and heterogeneous iron catalysis were recorded by the isolation of novel Fe nanocluster architectures that act as catalyst reservoirs and soluble seeds of particle growth.
- Gieshoff, Tim N.,Chakraborty, Uttam,Villa, Matteo,Jacobi von Wangelin, Axel
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supporting information
p. 3585 - 3589
(2017/03/21)
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- Transforming Olefins into γ,δ-Unsaturated Nitriles through Copper Catalysis
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We have developed a strategy to transform olefins into homoallylic nitriles through a mechanism that combines copper catalysis with alkyl nitrile radicals. The radicals are easily generated from alkyl nitriles in the presence of the mild oxidant di-tert-butyl peroxide. This cross-dehydrogenative coupling between simple olefins and alkylnitriles bears advantages over the conventional use of halides and toxic cyanide reagents. With this method, we showcase the facile synthesis of a flavoring agent, a natural product, and a polymer precursor from simple olefins.
- Wu, Xuesong,Riedel, Jan,Dong, Vy M.
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supporting information
p. 11589 - 11593
(2017/09/11)
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- Copper-Catalyzed Vicinal Diphosphination of Styrenes: Access to 1,2-Bis(diphenylphosphino)ethane-Type Bidentate Ligands from Olefins
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A copper/N-heterocyclic carbene (NHC) catalyzed oxidative vicinal diphosphination of styrenes with diphenyl(trimethylsilyl)phosphine proceeds in the presence of LiOtBu and a pyridine N-oxide/MnO2combined oxidant to deliver the corresponding 1,2-bis(diphenylphosphino)ethanes (DPPEs) in good yields. The present copper catalysis can provide access to the DPPE-type ligands directly from the relatively simple alkenes.
- Okugawa, Yuto,Hirano, Koji,Miura, Masahiro
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supporting information
p. 13558 - 13561
(2016/10/21)
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- Direct Olefination of Alcohols with Sulfones by Using Heterogeneous Platinum Catalysts
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Carbon-supported Pt nanoparticles (Pt/C) were found to be effective heterogeneous catalysts for the direct Julia olefination of alcohols in the presence of sulfones and KOtBu under oxidant-free conditions. Primary alcohols, including aryl, aliphatic, allyl, and heterocyclic alcohols, underwent olefination with dimethyl sulfone and aryl alkyl sulfones to give terminal and internal olefins, respectively. Secondary alcohols underwent methylenation with dimethyl sulfone. Under 2.5 bar H2, the same reaction system was effective for the transformation of alcohol OH groups to alkyl groups. Structural and mechanistic studies of the terminal olefination system suggested that Pt0 sites on the Pt metal particles are responsible for the rate-limiting dehydrogenation of alcohols and that KOtBu may deprotonate the sulfone reagent. The Pt/C catalyst was reusable after the olefination, and this method showed a higher turnover number (TON) and a wider substrate scope than previously reported methods, which demonstrates the high catalytic efficiency of the present method. Olefination of alcohols: The first heterogeneous catalytic terminal and internal olefination of primary alcohols and methylenation of secondary alcohols with sulfones, a reusable carbon-supported Pt catalyst, and KOtBu is reported (see scheme).
- Hakim Siddiki,Touchy, Abeda Sultana,Kon, Kenichi,Shimizu, Ken-Ichi
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p. 6111 - 6119
(2016/04/26)
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- Difluoroalkylation/C-H Annulation Cascade Reaction Induced by Visible-Light Photoredox Catalysis
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We report the first example of difluoroalkylation/C-H annulation cascade reactions of cyclopropyl olefins induced by visible-light photoredox catalysis regioselectively affording partially hydrogenated naphthalenes and quinolines with a variety of difluorinated side chains. The alkylation reagent could be extended to monofluoro and trifluoro reagents, nitrile and malonate. The regioselectivity was investigated by means of density functional theory calculations.
- Li, Jin,Chen, Jingzhi,Jiao, Wei,Wang, Guoqiang,Li, Ying,Cheng, Xu,Li, Guigen
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p. 9992 - 10001
(2016/10/31)
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- Iodothiocyanation/Nitration of Allenes with Potassium Thiocyanate/Silver Nitrite and Iodine
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Direct strategies for the iodothiocyanation and iodonitration of allenes have been developed. In this process, potassium thiocyanate/silver nitrite and molecular iodine are used as the source of SCN, ONO2and iodine to provide the desired products in moderate to good yields with high stereoselectivity. (Figure presented.).
- Yang, Xiaodong,She, Yue,Chong, Ya,Zhai, Huichun,Zhu, He,Chen, Baohua,Huang, Guosheng,Yan, Rulong
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supporting information
p. 3130 - 3134
(2016/10/09)
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- Copper-catalyzed oxidative amination and allylic amination of alkenes
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Enamines and enamides are useful synthetic intermediates and common components of bioactive compounds. A new protocol for their direct synthesis by a net alkene C-H amination and allylic amination by using catalytic Cu II in the presence of MnO2 is reported. Reactions between N-aryl sulfonamides and vinyl arenes furnish enamides, allylic amines, indoles, benzothiazine dioxides, and dibenzazepines directly and efficiently. Control experiments further showed that MnO2 alone can promote the reaction in the absence of a copper salt, albeit with lower efficiency. Mechanistic probes support the involvement of nitrogen-radical intermediates. This method is ideal for the synthesis of enamides from 1,1-disubstituted vinyl arenes, which are uncommon substrates in existing oxidative amination protocols. A new protocol for the direct synthesis of enamides and allylic amines by oxidative N-H/C-H coupling of N-sulfonylanilines with vinylarenes is presented. The reaction works in both inter- and intramolecular modes and is catalyzed by copper salts by using MnO2 as the stoichiometric oxidant (see scheme). Nitrogen heterocycles including indoles, benzothiazine dioxides, and dibenzazepines can be formed. Copyright
- Liwosz, Timothy W.,Chemler, Sherry R.
-
supporting information
p. 12771 - 12777
(2013/10/01)
-
- Electronic polarizability-based stereochemical model for Sharpless AD reactions
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Softness really is the hard force! Reported here was the critical yet long-overlooked role of electronic polarizability (i.e., softness) effect in controlling absolute stereochemical courses of general asymmetric induction events. Thus, a sensitive dependence of the sense of chiral induction on an alkene substrate's substituent electronic polarizability character was uncovered from a range of structurally highly comparable Sharpless asymmetric dihydroxylation (AD) systems, from which a new polarizability-based stereochemical model of predictive power was suggested.
- Han, Peng,Wang, Ruji,Wang, David Zhigang
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supporting information; experimental part
p. 8873 - 8878
(2011/12/02)
-
- Diethylaluminum chloride mediated vinylsilane synthesis: Comparison of different solvent systems
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Aromatic ketones were converted to one-carbon elongated-vinylsilanes in a convenient one-pot operation via the Peterson protocol. Reactions were conducted in two different solvents for comparison: pentane and triethylamine. Results indicate that triethylamine appeared to be a more suitable solvent for such a transformation producing vinylsilanes with great chemo- and stereo-selectivity than pentane.
- Kwan, Man Lung,Battiste, Merle A.,Macala, Megan K.,Aybar, Sylvia C.,James, Nicholas C.,Haoui, Joseph J.
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p. 1943 - 1950
(2007/10/03)
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- Aryl and vinyl cyclopropanes through the in situ generation of B- cyclopropyl-9-BBN and its Suzuki-Miyaura coupling
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Dihydroboration of propargyl bromide with 9-BBN-H followed by treatment of the adduct with aqueous sodium hydroxide affords the hydroxy(cycloropropyl)borate complex (1), which undergoes efficient palladium-catalyzed cross-coupling to produce a variety of aryl and vinyl cyclopropanes (2) in good to excellent yields. (C) Elsevier Science Ltd.
- Soderquist, John A.,Huertas, Ramon,Leon-Colon, Gisela
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p. 4251 - 4255
(2007/10/03)
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- Reactivity and selectivity in the oxidation of styrene derivatives. V. studies on the oxidation of α-substituted styrenes
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The liquid phase oxidation of α-phenyl-1a, α-trimethylsilyloxy 1b, α-cyclopropyl-1c, α-trifluoromethyl-1d styrene, and styrene 1e with oxygen in chlorobenzene and cumene solution in the temperature range 55-125°C was investigated. The product yields were determined gaschromatographically. The epoxide selectivity increases up to 90°C with increasing temperature. The epoxides of 1a and 1c rearrange at higher temperatures, therefore their yield decreases. The relative chain propagation constants (kpC=C) were determined by competitive oxidations of cumene. WILEY-VCH Verlag GmbH, 1999.
- Suprun
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- Palladium-catalyzed annulation of vinylic cyclopropanes and cyclobutanes
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Aryl iodides substituted in the ortho position by OH, CH2OH, NH2, NHTs and CH(CO2Et)2 groups react with vinylic cyclopropanes and cyclobutanes in the presence of a palladium catalyst and an appropriate base to afford good yields of heterocycles and carbocycles. The annulation products apparently arise by (1) palladium(0) formation and insertion into the carbon-iodine bond of the aryl iodide to generate an arylpalladium intermediate, (2) arylpalladium addition across the carbon-carbon double bond of the alkene, (3) ring-opening of the cyclopropane or cyclobutane by carbon-palladium beta elimination, (4) rearrangement of the resulting unsaturated alkylpalladium compound to a π-allylpalladium compound by a series of reversible palladium hydride beta elimination and readdition steps, (5) anion formation by removal of a proton from the functional group present on the arene, and (6) nucleophilic substitutions of the palladium by the resulting anion.
- Larock, Richard C.,Eul Kgun, Yum
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p. 2743 - 2758
(2007/10/03)
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- Bimolecular Formation of Radicals by H-Transfer, 7. - Bimolecular Formation of Radicals via H-Transfer with Catalysis by 7H-Benzanthracene
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The transfer hydrogenation of α-methylstyrene (2) by 9,10-dihydroanthracene (1) (DHA) with 7H-benzanthracene (8) as a catalyst proceeds already at 210-260 deg C.Isotopic labeling, ESR spectroscopy, radical clock experiments, solvents effects, and thermochemical calculations support the postulated stepwise radical mechanism induced by bimolecular formation of radicals. - Key Words: Molecule-induced radical formation, kinetics of / Catalysis / ESR spectroscopy / Radical clock / Isokinetic relationship
- Gerst, Matthias,Morgenthaler, Jens,Ruechardt, Christoph
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p. 691 - 696
(2007/10/02)
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- Peterson (silyl-Wittig) methylenation of carbonyl compounds using Nafion-H catalyzed hydroxy-trimethylsilane elimination of β-hydroxysilanes
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The Peterson (silyl-Wittig) methylenation of carbonyl compounds is significantly improved by convenient hydroxy-trimethylsilane elimination of the intermediate β-hydroxysilanes using perfluoroalkanesulfonic acid (Nafion-H) catalysis. These high yield reactions proceed at room temperature, and the workup involves only filtration of the catalyst.
- Olah,Reddy,Prakash
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- A High-Yield Regiospecific Synthesis of Keto Oximes from Aryl-Conjugated Ethylenes and Ethyl Nitrite in the Presence of Cobalt Complex and BH4- Ion
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The title reaction of substituted styrenes, 1-phenyl-1,3-butadiene, and some cyclic aryl-conjugated ethylenes proceeds smoothly at room temperature, affording the corresponding oximes in moderate to nearly quantitative yields.The reaction mechanism is discussed on the basis of the formation of an alkylcobalt intermediate and its subsequent reaction with ethyl nitrite.
- Okamoto, Tadashi,Kobayashi, Kenji,Oka, Shinzaburo,Tanimoto, Shigeo
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p. 4897 - 4901
(2007/10/02)
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- Formation of Cyclized, including 3,5-Cyclosteroid, Alkenes from β,γ-Unsaturated Grignard Reagents induced by Elimination of a δ-Alkoxy Group
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Grignard reagents and lithium salts prepared from the epimers of 3β-chloro-7ξ-methoxycholest-5-ene, (2) and (3), were shown to undergo a stereoselective rearrangement/elimination process to give 3α,5α-cyclocholest-6-ene (6) as the major product.Similarly the Grignard reagent from a mixture of (Z)- and (E)-5-chloro-1-methoxy-2-phenylpent-2-ene, (10) and (11), gave 1-cyclopropyl-1-phenylethene (9).Reactions of the corresponding Grignard reagents lacking methoxy groups with water or carbon dioxide gave unrearranged products.It was concluded that cyclizations of this type can be brought about despite an unfavourable equilibrium between ring-opened and ring-closed Grignard intermediates, due to the possibility of conversion of an alkylmagnesium halide into a thermodynamically more stable alkoxymagnesium halide from proposed ring-closed Grignard intermediates.
- Fischer, Peter M.,Howden, Merlin E. H.
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p. 475 - 480
(2007/10/02)
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- REACTION OF 2,2-DISUBSTITUTED 1-(DIBROMOMETHYLENE)CYCLOPROPANES WITH METHYLLITHIUM
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In the reaction of 2,2-disubstituted 1-(dibromomethylene)cyclopropanes with methyllithium 4,4-disubstituted 1-buten-3-ynes and 2,2-disubstituted (1-bromoethylidene)cyclopropanes are formed in ratios which depend on the character of substitution in the cyclopropane ring.
- Kostikov, R. R.,Molchanov, A. P.,Nagi, Sh. M.
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p. 1291 - 1297
(2007/10/02)
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