- Electrochemical Proton Reduction over Nickel Foam for Z-Stereoselective Semihydrogenation/deuteration of Functionalized Alkynes
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Selective reduction strategies based on abundant-metal catalysts are very important in the production of chemicals. In this paper, a method for the electrochemical semihydrogenation and semideuteration of alkynes to form Z-alkenes was developed, using a simple nickel foam as catalyst and H3O+ or D3O+ as sources of hydrogen or deuterium. Good yields and excellent stereoselectivities (Z/E up to 20 : 1) were obtained under very mild reaction conditions. The reaction proceeded with terminal and nonterminal alkynes, and also with alkynes containing easily reducible functional groups, such as carbonyl groups, as well as aryl chlorides, bromides, and even iodides. The nickel-foam electrocatalyst could be recycled up to 14 times without any change in its catalytic properties.
- Valiente, Alejandro,Martínez-Pardo, Pablo,Kaur, Gurpreet,Johansson, Magnus J.,Martín-Matute, Belén
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- Olefination via Cu-Mediated Dehydroacylation of Unstrained Ketones
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The dehydroacylation of ketones to olefins is realized under mild conditions, which exhibits a unique reaction pathway involving aromatization-driven C-C cleavage to remove the acyl moiety, followed by Cu-mediated oxidative elimination to form an alkene between the α and β carbons. The newly adopted N′-methylpicolinohydrazonamide (MPHA) reagent is key to enable efficient cleavage of ketone C-C bonds at room temperature. Diverse alkyl- and aryl-substituted olefins, dienes, and special alkenes are generated with broad functional group tolerance. Strategic applications of this method are also demonstrated.
- Dong, Guangbin,Xu, Yan,Zhou, Xukai
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supporting information
p. 20042 - 20048
(2021/12/03)
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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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- A Systematic Study of the Effects of Complex Structure on Aryl Iodide Oxidative Addition at Bipyridyl-Ligated Gold(I) Centers
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A combined theoretical and experimental approach has been used to study the unusual mechanism of oxidative addition of aryl iodides to [bipyAu(C2H4)]+ complexes. The modular nature of this system allowed a systematic assessment of the effects of complex structure. Computational comparisons between cationic gold and the isolobal (neutral) Pd0 and Pt0 complexes revealed similar mechanistic features, but with oxidative addition being significantly favored for the group 10 metals. Further differences between Au and Pd were seen in experimental studies: studying reaction rates as a function of electronic and steric properties showed that ligands bearing more electron-poor functionality increase the rate of oxidative addition; in a complementary way, electron-rich aryl iodides give faster rates. This divergence in mechanism compared to Pd suggests that Ar?X oxidative addition with Au can underpin a broad range of new or complementary transformations.
- Bower, John F.,Cadge, Jamie A.,Russell, Christopher A.
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supporting information
p. 24976 - 24983
(2021/10/20)
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- Carbosulfenylation of Alkenes with Organozinc Reagents and Dimethyl(methylthio)sulfonium Trifluoromethanesulfonate
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The electrophilic alkylthiolation of alkenes, initiated by dimethyl(methylthio)sulfonium salts and the subsequent addition of various heteronucleophilies has been well-established. Regarding the use of carbon nucleophiles, however, only carefully designed sp-type carbon sources have been successfully applied. We herein present our findings on the methylthiolation of alkenes with dimethyl(methylthio)sulfonium trifluoromethanesulfonate, followed by carbon-carbon bond formation in the presence of organozinc reagents, thus achieving a catalyst-free protocol toward to the carbosulfenylation of alkenes.
- Tang, Meizhong,Han, Shuxiong,Huang, Shenglan,Huang, Shenlin,Xie, Lan-Gui
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supporting information
p. 9729 - 9734
(2020/12/21)
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- Photo-induced Decarboxylative Heck-Type Coupling of Unactivated Aliphatic Acids and Terminal Alkenes in the Absence of Sacrificial Hydrogen Acceptors
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1,2-Disubstituted alkenes such as vinyl arenes, vinyl silanes, and vinyl boronates are among the most versatile building blocks that can be found in every sector of chemical science. We herein report a noble-metal-free method of accessing such olefins through a photo-induced decarboxylative Heck-type coupling using alkyl carboxylic acids, one of the most ubiquitous building blocks, as the feedstocks. This transformation was achieved in the absence of external oxidants through the synergistic combination of an organo photo-redox catalyst and a cobaloxime catalyst, with H2 and CO2 as the only byproducts. Both control experiments and DFT calculations supported a radical-based mechanism, which eventually led to the development of a selective three-component coupling of aliphatic carboxylic acids, acrylates, and vinyl arenes. More than 90 olefins across a wide range of functionalities were effectively synthesized with this simple protocol.
- Cao, Hui,Jiang, Heming,Feng, Hongyu,Kwan, Jeric Mun Chung,Liu, Xiaogang,Wu, Jie
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supporting information
p. 16360 - 16367
(2018/11/27)
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- Metathesis-active ligands enable a catalytic functional group metathesis between aroyl chlorides and aryl iodides
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Current methods for functional group interconversion have, for the most part, relied on relatively strong driving forces which often require highly reactive reagents to generate irreversibly a desired product in high yield and selectivity. These approaches generally prevent the use of the same catalytic strategy to perform the reverse reaction. Here we describe a catalytic functional group metathesis approach to interconvert, under CO-free conditions, two synthetically important classes of electrophiles that are often employed in the preparation of pharmaceuticals and agrochemicals—aroyl chlorides (ArCOCl) and aryl iodides (ArI). Our reaction design relies on the implementation of a key reversible ligand C–P bond cleavage event, which enables a non-innocent, metathesis-active phosphine ligand to mediate a rapid aryl group transfer between the two different electrophiles. Beyond enabling a practical and safer approach to the interconversion of ArCOCl and ArI, this type of ligand non-innocence provides a blueprint for the development of a broad range of functional group metathesis reactions employing synthetically relevant aryl electrophiles.
- Lee, Yong Ho,Morandi, Bill
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p. 1016 - 1022
(2018/09/06)
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- A method for the preparation of entecavir (by machine translation)
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The invention discloses a compound of formula (I) shown in the method for the preparation of entecavir, the method according to the following steps: shown in formula (II) intermediate of the raw materials, as shown in formula (III) of the polystyrene load the high price of iodine is the oxidizing agent, in order to of a catalytic amount of N - hydroxy imide compound as co-oxidizing agent, under the action of the additive, in formula (I). The beneficial effect of the present invention is of relatively expensive the iodine passes through polystyrene after load, can be a simple filtration recovery, recycling, the production cost is low, the preparation method is suitable for industrial production. (by machine translation)
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Paragraph 0006; 0012; 0013
(2018/10/11)
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- Synthesis of Functionalized Alkenes by a Transition-Metal-Free Zweifel Coupling
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The Zweifel reaction is a powerful method for the synthesis of alkenes, serving as a transition-metal-free alternative to the Suzuki-Miyaura reaction. To date, the scope of the Zweifel coupling has been rather narrow and has focused mainly on the coupling of vinyllithium reagents to synthesize simple aryl- and alkyl-substituted olefins. Herein, the development of a general transition-metal-free coupling process enabling the coupling of Grignard reagents or organolithiums is described. This method enables the enantiospecific synthesis of a wide variety of functionalized acyclic and cyclic olefin products.
- Armstrong, Roly J.,Niwetmarin, Worawat,Aggarwal, Varinder K.
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supporting information
p. 2762 - 2765
(2017/05/24)
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- Diastereoselective C?H Bond Amination for Disubstituted Pyrrolidines
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We report herein the improved diastereoselective synthesis of 2,5-disubstituted pyrrolidines from aliphatic azides. Experimental and theoretical studies of the C?H amination reaction mediated by the iron dipyrrinato complex (AdL)FeCl(OEt2) provided a model for diastereoinduction and allowed for systematic variation of the catalyst to enhance selectivity. Among the iron alkoxide and aryloxide catalysts evaluated, the iron phenoxide complex exhibited superior performance towards the generation of syn 2,5-disubstituted pyrrolidines with high diastereoselectivity.
- Iovan, Diana A.,Wilding, Matthew J. T.,Baek, Yunjung,Hennessy, Elisabeth T.,Betley, Theodore A.
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supporting information
p. 15599 - 15602
(2017/11/16)
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- Palladium-Catalysed Desulfitative Heck Reaction Tolerant to Aryl Carbon-Halogen Bonds for Access to (Poly)halo-Substituted Stilbene or Cinnamate Derivatives
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The palladium-catalysed desulfitative Heck type reaction of (poly)halo-substituted benzenesulfonyl chlorides with alkenes was investigated. Styrene or acrylates in the presence of bromo- or iodobenzenesulfonyl chlorides and a phosphine-free palladium catalyst were found to afford the expected β-arylated Heck type products with complete regio- and stereoselectivities. The reaction tolerates a variety of substituents on the halobenzenesulfonyl chloride. Moreover, no cleavage of the C-Br and C-I bonds was observed in the course of these reactions, allowing further transformations. Using 4-bromobenzenesulfonyl chloride as the central unit, consecutive desulfitative Heck type reaction followed by palladium-catalysed direct arylation allowed to prepare heteroarylated stilbene derivatives in only two steps.
- Skhiri, Aymen,Salem, Ridha Ben,Soulé, Jean-Francois,Doucet, Henri
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p. 3097 - 3106
(2016/09/09)
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- Wittig Reactions of Trialkylphosphine-derived Ylides: New Directions and Applications in Organic Synthesis
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The development of semi-stabilized, stabilized, and functionalized ylides derived from short-chain trialkylphosphines in the Wittig-type olefination reactions toward the synthesis of alkenes, including stilbenes, styrenes, and 1,3-dienes, as well as reagents for homologation reactions, are described. The methods allow easy access to alkenes with high (E)-stereoselectivity in good yield. These reactions are conducted with weak bases in aqueous media, which allows easy separation of water-soluble phosphine oxides. The development of a mild organocatalytic process for the Wittig reaction and extension toward the preparation of reporter stilbenes under biological conditions are also described. Applications toward the preparation of biologically active natural products and derivatives are discussed.
- McNulty, James,McLeod, David,Das, Priyabrata,Zepeda-Velázquez, Carlos
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p. 619 - 632
(2016/01/15)
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- Supported palladium nanoparticles as heterogeneous ligand-free catalysts for the Hiyama C-C coupling of vinylsilanes and halobenzenes leading to styrenes
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The Hiyama C-C coupling reaction of a wide range of aryl iodides and vinylsilanes has been performed using ligand-free solid catalysts based on supported palladium nanoparticles. Among the supports tested (Mg, TiO 2, CeO2 and active carbon), the most active catalysts were those in which palladium is supported on MgO and TiO2. Analogous Pt and Au materials were inefficient to promote this reaction. Leaching tests suggest that there is some contribution of dissolved Pd since Pd in solution has been detected and the scavenging test decreases the initial reaction rate. Although the solid Pd catalysts can be reused, it was, however, observed that they undergo a certain deactivation upon use that can be attributed to several factors including the presence of inorganic compounds on the catalyst, Pd leaching or agglomeration of Pd NPs.
- Grirrane, Abdessamad,Garcia, Hermenegildo,Corma, Avelino
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- Sterically controlled iodination of arenes via iridium-catalyzed C-H borylation
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A mild method to prepare aryl and heteroaryl iodides by sequential C-H borylation and iodination is reported. The regioselectivity of this process is controlled by steric effects on the C-H borylation step and is complementary to existing methods to form aryl iodides. The iodination of boronic esters has potential for the synthesis of radiolabeled aryl iodides, as demonstrated by the concise synthesis of a potential tracer for SPECT imaging.
- Partridge, Benjamin M.,Hartwig, John F.
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supporting information
p. 140 - 143
(2013/03/28)
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- Transition metal photoredox catalysis of radical thiol-ene reactions
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We describe the anti-Markovnikov hydrothiolation of olefins using visible-light-absorbing transition metal photocatalysts. The key thiyl radical intermediates are generated upon quenching of photoexcited Ru*(bpz) 32 with a variety of thiols. The adducts of a wide variety of olefins and thiols are formed in excellent yield (73-99%).
- Tyson, Elizabeth L.,Ament, Michael S.,Yoon, Tehshik P.
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p. 2046 - 2050
(2013/03/29)
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- Cobalt-catalyzed preparation of arylindium reagents from aryl and heteroaryl bromides
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A cobalt-bathophenanthroline catalyst has been developed for the direct preparation of a variety of arylindium reagents from the corresponding aryl and heteroaryl bromides in the presence of indium metal and lithium chloride. The thus-formed arylindium reagents undergo efficient palladium-catalyzed cross-coupling reactions with aryl iodides, tolerating various functional groups including hydroxy and free amino groups.
- Adak, Laksmikanta,Yoshikai, Naohiko
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experimental part
p. 7563 - 7568
(2011/11/12)
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- A direct synthesis of functionalized styrenes and terminal 1,3-dienes via aqueous Wittig chemistry with formalin
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A direct synthesis of functionalized styrenes including synthetically valuable styryl halides and terminal 1,3-dienes is reported directly from benzylic and allylic alcohols and aqueous formalin involving microwave assisted phosphonium salt formation and Wittig olefination under mildly basic conditions.
- Das, Priyabrata,McLeod, David,McNulty, James
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experimental part
p. 199 - 201
(2011/02/26)
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- Tetraorganoindates as Nucleophilic Coupling Partners in Pd-Catalyzed Cross-Coupling Reactions
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(Equation presented) In situ generated ate complex In situ-generated tetraorganoindate complexes from the reaction of 1 equiv of indium trichloride with 4 equiv of appropriate organometallics are efficient nucleophiles in Pd-catalyzed cross-coupling reactions. In this novel reaction tetraorganoindates containing methyl, 1°- and 2°-alkyl, vinyl, alkynyl, and aryl groups transfer the four organic groups to a variety of electrophiles with high atom efficiency.
- Lee, Phil Ho,Lee, Sung Wook,Seomoon, Dong
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p. 4963 - 4966
(2007/10/03)
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- Mild preparation of haloarenes by ipso-substitution of arylboronic acids with N-halosuccinimides
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Aryl and heteroaryl boronic acids react with N-iodosuccinimide and N-bromosuccinimide to give the corresponding iodo-and bromo- arenes in good to excellent yields. The reaction is usually highly regioselective and yields only the ipso-substituted product. Esters of arylboronic acids react similarly, but less readily.
- Thiebes, Christoph,Prakash, G. K. Surya,Petasis, Nicos A.,Olah, George A.
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p. 141 - 142
(2007/10/03)
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- Palladium-catalyzed cross-coupling of organostannanes with iodanes
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The palladium-catalyzed coupling of organostannanes with iodanes (Koser's and Zefirov's reagents) in the presence of palladium catalyst was accomplished at room temperature under aqueous conditions to afford phenyl- or 4-iodophenyl-substituted products depending on the iodanes used.
- Kang, Suk-Ku,Lee, Hong-Woo,Kim, Jae-Sun,Choi, Sang-Chul
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p. 3723 - 3726
(2007/10/03)
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- Stereospecific Arylation of Alkenylsilanes with Arylpalladium Acetates
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Alkenyltrimethylsilanes ((E)- and (Z)-RCH=CHSiMe3: R = H, Ph, n-C6H13 and CH3OCH2) stereospecifically reacted at 40 deg C or room temperature with in situ generated phenylpalladium acetate to produce R(Ph)C=CSiMe3 and RCH=C(Ph)SiMe3 with inversion of their geometry.The arylation of CH2=CHSiMe3 with arylpalladium acetates gave (E)-ArCH=CHSiMe3 (Ar = XPH; X = H, 4-Me, 4-MeO, 4-Br, 4-I, 4-EtOCO, and 4-NO2) in good yields.
- Ikenaga, Kazutoshi,Kikukawa, Kiyoshi,Matsuda, Tsutomu
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p. 1276 - 1280
(2007/10/02)
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- REACTION OF DIAZONIUM SALTS WITH TRANSITION METALS IX. REACTION OF VINYLTRIMETHYLSILANE WITH ARENEDIAZONIUM TETRAFLUOROBORATES UNDER PALLADIUM(0) CATALYSIS
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Arenediazonium tetrafluoroborates (ArN2BF4 where Ar = Ph, 4-MeC6H4, 4-BrC6H4, 4-IC6H4 and 4-NO2C6H4) reacted easily with CH2=CHSiMe3 at 25 deg C to give ArCH=CH2, (E)-ArCH=CHSiMe3 and Ar(Me3Si)C=CH2 in excellent yields under palladium(0) catalysis. (E)-ArCH=CHSiMe3 compounds were obtained predominantly and isolated in good yields by using an excess of CH2=CHSiMe3 over ArN2BF4.Protodesilylation of the reaction mixture afforded styrene derivatives.
- Kikukawa, Kiyoshi,Ikenaga, Kazutoshi,Kono, Kiyoshi,Toritani, Koji,Wada, Fumio,Matsuda, Tsutomu
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p. 277 - 282
(2007/10/02)
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