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Design of Hemilabile N,N,N-Ligands in Copper-Catalyzed Enantioconvergent Radical Cross-Coupling of Benzyl/Propargyl Halides with Alkenylboronate Esters
The enantioconvergent radical C(sp3)-C(sp2) cross-coupling of alkyl halides with alkenylboronate esters is an appealing tool in the assembly of synthetically valuable enantioenriched alkenes owing to the ready availability, low toxicity, and air/moisture stability of alkenylboronate esters. Here, we report a copper/chiral N,N,N-ligand catalytic system for the enantioconvergent cross-coupling of benzyl/propargyl halides with alkenylboronate esters (>80 examples) with good functional group tolerance. The key to the success is the rational design of hemilabile N,N,N-ligands by mounting steric hindrance at the ortho position of one coordinating quinoline ring. Thus, the newly designed ligand could not only promote the radical cross-coupling process in the tridentate form but also deliver enantiocontrol over highly reactive alkyl radicals in the bidentate form. Facile follow-up transformations highlight its potential utility in the synthesis of various enantioenriched building blocks as well as in the late-stage functionalization for drug discovery.
Wang, Peng-Fei,Yu, Jiao,Guo, Kai-Xin,Jiang, Sheng-Peng,Chen, Ji-Jun,Gu, Qiang-Shuai,Liu, Ji-Ren,Hong, Xin,Li, Zhong-Liang,Liu, Xin-Yuan
p. 6442 - 6452
(2022/04/19)

Custom-Made Pyrene Photocatalyst-Promoted Desulfonylation of Arylethenyl Sulfones Using Green-Light-Emitting Diodes
The Sonogashira coupling of 1,3,6,8-tetrabromopyrene with 4-[(-)-β-citronellyloxy]phenylethyne was employed to synthesize 1,3,6,8-tetra[4-(citronellyloxy)phenylethynyl]pyrene. The pyrene derivative catalyzed the reductive desulfonylation of ethenyl sulfones via visible-light irradiation (514 nm green light-emitting diodes) in the presence of i -Pr 2NEt. The β-citronellyloxy groups provided the sufficient solubility to the highly π-expanded pyrene catalyst, and their polar oxygen functionalities enabled the easy separation of the catalyst from the products via column chromatography.
Watanabe, Hikaru,Nakajima, Kazuki,Ekuni, Kento,Edagawa, Ryota,Akagi, Yuta,Okuda, Yasuhiro,Wakamatsu, Kan,Orita, Akihiro
p. 2984 - 2994
(2021/03/04)

Ruthenium-catalysed oxidative coupling of vinyl derivatives and application in tandem hydrogenation
The first ruthenium-catalyzed oxidative homo- and cross-coupling of exclusive vinyl derivatives giving highly valued 1,3-diene building blocks is reported. The catalytic system is based on readily available reagents and it mainly delivers the E,E isomer. This methodology also enables the synthesis of adipic acid ester derivatives in a one-pot fashion after in situ ruthenium-catalyzed hydrogenation.
Abuhafez, Naba,Bruneau, Christian,Gramage-Doria, Rafael,Kamaraj, Raghu,Ruffin, Hervé
p. 5772 - 5776
(2021/09/10)

A Solid-Phase Assisted Flow Approach to In Situ Wittig-Type Olefination Coupling
Described herein is the development of a continuous flow, solid-phase triphenylphosphine (PS-PPh3) assisted protocol to facilitate the in situ coupling of reciprocal pairs of halogen and carbonyl functionalised molecular pairs by a Wittig olefination within 15 mins. The protocol entails injecting a single solution (1 : 1 CHCl3 : EtOH) containing the halogenated and carbonyl-based substrates into a continuously flowing stream of CHCl3 : EtOH (1 : 1), passed through a fixed bed of K2CO3 and PS-PPh3. With advancement to the previous PS-PPh3 coupling procedures, the method employs a traditional polystyrene-based immobilisation matrix, the substrate scope of the protocol extended to substituted ketones, secondary alkyl chlorides, and an unprotected maleimide scaffold.
Aldrich-Wright, Janice R.,Dankers, Christian,Gordon, Christopher P.,Polyzos, Anastasios,Tadros, Joseph
supporting information
p. 4184 - 4194
(2021/08/24)

Cobalt-Catalyzed Z to e Geometrical Isomerization of 1,3-Dienes
An efficient cobalt-catalyzed geometrical isomerization of 1,3-dienes is described. In the combination of a CoCl2 precatalyst with an amido-diphosphine-oxazoline ligand, the geometrical isomerization of E/Z mixtures of 1,3-dienes proceed in a stereoconvergent manner, affording (E) isomers in high stereoselectivity. This facile transformation features a broad substrate scope with good functional group tolerance and could be scaled up to the gram scale smoothly with a catalyst loading of 1 mol %.
Wang, Wei,He, Shuying,Zhong, Yuqing,Chen, Jianhui,Cai, Cheng,Luo, Yanshu,Xia, Yuanzhi
(2022/03/27)

Pd-Catalyzed Cross-Coupling of Organostibines with Styrenes to Give Unsymmetric (E)-Stilbenes and (1 E,3 E)-1,4-Diarylbuta-1,3-dienes and Fluorescence Properties of the Products
A general and effective palladium-catalyzed cross-coupling of organostibines with styrenes to give (E)-olefins was disclosed. By the use of an organostibine reagent, this method can produce unsymmetric (E)-1,2-diarylethylenes and (1E,3E)-1,4-diarylbuta-1,3-dienes in good yields with high E/Z selectivity and good functional group tolerance. Resveratrol and DMU-212 were synthesized in high yield. The protocol can be extended to the synthesis of (1E,3E,5E)-1,6-diphenylhexa-1,3,5-triene in 40% yield. Products 5e, 5f, and 7a showed good photoluminescence quantum yields ranging from 72 to 99%.
Zhang, Zhao,Zhang, Dejiang,Zhu, Longzhi,Zeng, Dishu,Kambe, Nobuaki,Qiu, Renhua
supporting information
p. 5317 - 5322
(2021/06/28)

Nickel- and Palladium-Catalyzed Cross-Coupling Reactions of Organostibines with Organoboronic Acids
A strategy for the formation of antimony-carbon bond was developed by nickel-catalyzed cross-coupling of halostibines. This method has been applied to the synthesis of various triaryl- and diarylalkylstibines from the corresponding cyclic and acyclic halostibines. This protocol showed a wide substrate scope (72 examples) and was compatible to a wide range of functional groups such as aldehyde, ketone, alkene, alkyne, haloarenes (F, Cl, Br, I), and heteroarenes. A successful synthesis of arylated stibine 3 a in a scale of 34.77 g demonstrates high synthetic potential of this transformation. The formed stibines (R3Sb) were then used for the palladium-catalyzed carbon–carbon bond forming reaction with aryl boronic acids [R?B(OH)2], giving biaryls with high selectivity, even the structures of two organomoieties (R and R′) are very similar. Plausible catalytic pathways were proposed based on control experiments.
Zhang, Dejiang,Le, Liyuan,Qiu, Renhua,Wong, Wai-Yeung,Kambe, Nobuaki
supporting information
p. 3104 - 3114
(2020/12/11)

Stereospecific Iron-Catalyzed Carbon (sp2)-Carbon (sp2) Cross-Coupling of Aryllithium with Vinyl Halides
We present herein an efficient synthetic protocol involving iron-catalyzed cross-coupling of organolithium compounds with vinyl halides as key coupling partners. More than 30 examples were obtained with moderate to good yields and high stereoselectivities. The practicality of this method is evidenced by a gram-scale synthesis. In addition, a preliminary mechanistic investigation was also performed.
Chen, Peng,Peng, Xiao-Shui,Wang, Zhi-Yong,Wong, Henry N. C.
supporting information
p. 4385 - 4390
(2021/06/27)

Asymmetric Aminomethylative Etherification of Conjugated Dienes with Aliphatic Alcohols Facilitated by Hydrogen Bonding
The asymmetric construction of allylic C-O bonds with primary or secondary aliphatic alcohols remains a substantial challenge in Pd-catalyzed allylation chemistry. Here, we report the development of an additive-free, palladium-catalyzed asymmetric aminomethylative etherification of conjugated dienes that enables the efficient, asymmetric O-allylation of primary and secondary aliphatic alcohols as well as water. Mechanism studies revealed that the hydrogen-bonding interaction between the alcohol and the in situ introduced aminomethyl moiety is critical to facilitate the nucleophilic addition of the alcohol to the π-allylpalladium species, which opened up the possibility of using aliphatic alcohols and water as nucleophilic substrates. This reaction tolerates a broad range of functional groups and shows remarkable regioselectivities and uniformly high enantioselectivities, which provides a direct and rapid approach to optically pure allylic 1,3-amino ethers and 1,3-amino alcohols from simple starting materials.
Chang, Rui,Cai, Shoule,Yang, Guoqing,Yan, Xuyang,Huang, Hanmin
supporting information
p. 12467 - 12472
(2021/08/30)

[Rh(Cod)Cl]2/Pph3?catalyzed dehydrogenative silylation of styrene derivatives with NBE as a hydrogen acceptor
Direct synthesis of arylalkenylsilanes by [Rh(COD)Cl]2/ PPh3-catalyzed dehydrogenative silylation of styrene derivatives with R3SiH (R = alkyl, alkoxy, aryl) was realized, in which norbornene (NBE) and PPh3 play a key role in achieving excellent selectivity in the formation of dehydrogenative silylation products. Moreover, this high-yielding transformation exhibits a broad substrate scope and good functional group tolerance.
Li, Chengyang,Lu, Wenkui,Wu, Xiaoyu,Xie, Xiaomin,Zhang, Zhaoguo
p. 3780 - 3788
(2020/11/23)

Co?MOF-74@Cu?MOF-74 Derived Bifunctional Co?C@Cu?C for One-Pot Production of 1, 4-Diphenyl-1, 3-Butadiene from Phenylacetylene
Carbon-supported metal nanoparticles (NPs) play important roles in heterogeneous catalysis. In particular, supported bimetallic catalytic systems can be promising multifunctional catalysts for one-pot tandem/cascade reactions, in which two or more successive independent reactions are realized in one pot. In this manuscript, we report the preparation of a carbon-supported bimetallic CoCu catalytic system (Co?C@Cu?C), with Co NPs wrapped by carbon-supported Cu NPs, from the pyrolysis of a core-shell structured Co?MOF-74@Cu?MOF-74. The as-obtained Co?C@Cu?C acts as a bifunctional catalyst for the transformation of phenylacetylene to 1, 4-diphenyl-1, 3-butadiene in one pot, in which supported metallic Cu NPs and Co NPs are active for the coupling and hydrogenation reaction respectively. By tuning the reaction rates of the coupling and the hydrogenation in this tandem reaction over the Co?C@Cu?C via changing the reaction medium and the reducing agent, an efficient direct transformation of phenylacetylene to 1, 4-diphenyl-1, 3-butadiene was realized. This work not only highlights the important role of MOFs in the preparation of multifunctional carbon supported metal NPs for heterogeneous catalysis, but also demonstrates the possibility of tuning the reaction rates of different catalytic steps in a tandem reaction to realize an efficient overall reaction.
Cai, Jingyu,Zhuang, Yuzheng,Chen, Yi,Xiao, Longqiang,Zhao, Yulai,Jiang, Xiancai,Hou, Linxi,Li, Zhaohui
p. 6241 - 6247
(2020/10/15)

Regioselectivity of the Chan–Lam coupling of ambident nitropyrazoles with trans-styrylboronic acid
Regioselectivity of the Chan–Lam coupling of ambident nitropyrazoles with trans-styrylboronic acid depends on the base and catalyst nature and can vary the N(1)/N(2)-isomer ratio from ～2: 1 to ～1: 2. 2-Methyl-4-nitro- and 2,4-dinitroimidazoles are unreact
Davydov, Dmitry V.,Oprunenko, Yurii F.,Sazonov, Petr K.
p. 185 - 187
(2020/05/25)

Copper quinolate: A simple and efficient catalytic complex for coupling reactions
We describe an effective and novel method to prepare N-aryl imidazoles via the copper quinolate-catalyzed N-arylation of aryl halides and imidazoles. A wide range of products were obtained in moderate to excellent yields under the optimal reaction conditions. Applying standard conditions, the model reaction could be performed on a gram scale. This method also presents a new avenue to the “click” reaction of terminal alkynes, benzyl bromide, and sodium azide and to the construction of C–C bonds by homocoupling of phenylboronic acid or phenylacetylene derivatives with the aid of copper quinolate.
Wu, Fengtian,Li, Huiqin,Xie, Jianwei
(2019/11/22)

Iron-Catalyzed Reductive Vinylation of Tertiary Alkyl Oxalates with Activated Vinyl Halides
We present herein a rare and efficient method for the creation of vinylated all carbon quaternary centers via Fe-catalyzed cross-electrophile coupling of vinyl halides with tertiary alkyl methyl oxalates. The reaction displays excellent functional group tolerance and broad substrate scope, which allows cascade radical cyclization and vinylation to afford complex bicyclic and spiral structural motifs. The reaction proceeds via tertiary alkyl radicals, and the putative vinyl-Br/Fe complexation appears to be crucial for activating the alkene and enabling a possibly concerted radical addition/C-Fe forming process.
Chen, Haifeng,Gong, Hegui,Yao, Ken,Ye, Yang
supporting information

(2020/03/13)

AgSbF6-Catalyzed: Anti -Markovnikov hydroboration of terminal alkynes
AgSbF6-Catalyzed anti-Markovnikov addition of pinacolborane (HBpin) to terminal alkynes to produce the E-vinylboronates is reported. This efficient methodology is scalable, compatible with sterically and electronically diverse alkynes, and works at room temperature under solvent-free condition. The utility of this method is demonstrated in the facile synthesis of the clinically important (E)-2,4,3′,5′-tetramethoxystilbene.
Mamidala, Ramesh,Pandey, Vipin K.,Rit, Arnab
p. 989 - 992
(2019/01/23)

Fluoroalkenylation of boronic acids: Via an oxidative Heck reaction
A fluoroalkenylation of boronic acids with fluoroalkyl alkenes has been developed. The Pd-catalyzed oxidative Heck coupling reaction proceeds under an oxygen atmosphere at room temperature, in the absence of a base and/or a ligand, showing excellent practicality of the process. This simple transformation is highly stereoselective to provide only E-isomers. In addition to the general approach using alkenes with functionalized fluoroalkyl reagents, this method, by transferring an aromatic system to the electron-deficient fluoroalkyl alkene, provides an efficient alternative method to yield valuable organofluorines.
Lee, Da Seul,Cho, Eun Jin
p. 4317 - 4325
(2019/05/06)

H2-Acceptorless Dehydrogenative Boration and Transfer Boration of Alkenes Enabled by Zirconium Catalyst
The first example of an efficient and direct dehydrogenative boration of alkenes for vinyl boronate ester synthesis was achieved using a zirconium catalyst. Our methodology avoids using precious transition metals, additional hydrogen acceptors, high temperatures, and long reaction times, which were required to overcome the reducing ability of borane, to give alkyl boronate esters. Detailed mechanistic studies revealed a reversible reaction pathway and further suggested applying the zirconium complex as a “shuttle catalyst” for transfer boration, which thus sidesteps the use of relatively sensitive borane.
Shi, Xiaonan,Li, Sida,Wu, Lipeng
p. 16167 - 16171
(2019/11/03)

The photoisomerization of: Cis, trans -1,2-dideuterio-1,4-diphenyl-1,3-butadiene in solution. No bicycle-pedal
cis,trans-1,2-Dideuterio-1,4-diphenyl-1,3-butadiene (ct-DPBd2) was synthesized and its cis-trans photoisomerization in cyclohexane-d12 (C6D12) at room temperature was monitored by 1H NMR spectroscopy. The results reveal formation of only trans,trans-1,2-dideuterio-1,4-diphenyl-1,3-butadiene (tt-DPBd2). The failure to detect formation of trans,cis-1,2-dideuterio-1,4-diphenyl-1,3-butadiene (tc-DPBd2) eliminates the possibility that an identity bicycle pedal process contributes to inefficiency in the cis-trans photoisomerization of cis,trans-1,4-diphenyl-1,3-butadiene (ct-DPB).
Saltiel, Jack,Redwood, Christopher E.,Ratheesh Kumar
p. 2174 - 2179
(2019/09/18)

Iron(III)/O2-Mediated Regioselective Oxidative Cleavage of 1-Arylbutadienes to Cinnamaldehydes
A simple, efficient, and environmentally benevolent regioselective oxidative cleavage of 1-arylbutadienes to cinnamaldehydes mediated by iron(III) sulfate/O2 has been developed. The reaction offered good yields and excellent regioselectivity and showed good functional group tolerance (31 examples). The method is important, as few reports with limited substrate scope are available for such excellent oxidative cleavage of conjugated dienes.
Bhowmik, Amit,Fernandes, Rodney A.
supporting information
p. 9203 - 9207
(2019/11/14)

A POCO type pincer complex of iridium: Synthesis, characterization, and catalysis
A convenient synthesis of a new POCO-type pincer ligand, “tBuPOCOH” (3-(di-tert-butylphosphinito)acetophenone is reported. Metallation using [Ir(COD)Cl]2 provides the dimeric species (μ-Cl-[tBuPOCOIrHCl]2) (1a) as a major product, along with isomer 1b. Though not fully characterized, 1b is shown to be chemically equivalent to 1a by a series of experiments with AgOTf and CO which lead to formation of a single product, tBuPOCOIr(CO)HOTf (3). The 1a/b mixture gives inferior results to iPrPCPIr when used as pre-catalyst in the dehydrogenative coupling of vinyl arenes, though olefin isomerization activity is enhanced. This system was also evaluated in the Geurbet conversion of ethanol to n-butanol and higher alcohols. The CO adducts of 1a/b, cis/trans-2, were found to give the best results as pre-catalyst, achieving a 33% yield of n-butanol and an overall 47% yield of n-alcohols with a catalyst loading of 0.5% when heated at 150 °C for 4 hours. This represents the first example of a pincer ligated iridium complex as catalyst in the Geurbet reaction of ethanol.
Wilklow-Marnell, Miles,Brennessel, William W.
p. 83 - 91
(2019/01/08)

Ligand-Free Iron-Catalyzed Carbon (sp2)-Carbon (sp2) Oxidative Homo-Coupling of Alkenyllithiums
A new strategy was developed for the efficient synthesis of di-, tetra-, and hexa-substituted 1,3-butadienes. This one-pot procedure involves lithium-iodine exchange to generate the corresponding vinyllithium intermediates. A subsequent iron-catalyzed ligand-free oxidative homo-coupling eventually led to the formation of 1,3-butadienes in acceptable to excellent isolated yields.
Zhong, Zhuliang,Wang, Zhi-Yong,Ni, Shao-Fei,Dang, Li,Lee, Hung Kay,Peng, Xiao-Shui,Wong, Henry N. C.
supporting information
p. 700 - 704
(2019/02/07)

Stereospecific Iron-Catalyzed Carbon(sp2)-Carbon(sp3) Cross-Coupling with Alkyllithium and Alkenyl Iodides
An efficient synthetic protocol involving iron-catalyzed cross-coupling reactions between organolithium compounds and alkenyl iodides as key coupling partners was achieved. More than 30 examples were obtained with moderate to good yields and high stereospecificity. Gram-scale and synthetic applications of this procedure are recorded herein to demonstrate its feasibility and potential utilization.
Lu, Xiao-Lin,Shannon, Mark,Peng, Xiao-Shui,Wong, Henry N. C.
supporting information
p. 2546 - 2549
(2019/03/26)

Epoxidation of Cyclooctene Using Water as the Oxygen Atom Source at Manganese Oxide Electrocatalysts
Epoxides are useful intermediates for the manufacture of a diverse set of chemical products. Current routes of olefin epoxidation either involve hazardous reagents or generate stoichiometric side products, leading to challenges in separation and significant waste streams. Here, we demonstrate a sustainable and safe route to epoxidize olefin substrates using water as the oxygen atom source at room temperature and ambient pressure. Manganese oxide nanoparticles (NPs) are shown to catalyze cyclooctene epoxidation with Faradaic efficiencies above 30%. Isotopic studies and detailed product analysis reveal an overall reaction in which water and cyclooctene are converted to cyclooctene oxide and hydrogen. Electrokinetic studies provide insights into the mechanism of olefin epoxidation, including an approximate first-order dependence on the substrate and water and a rate-determining step which involves the first electron transfer. We demonstrate that this new route can also achieve a cyclooctene conversion of ～50% over 4 h.
Jin, Kyoungsuk,Maalouf, Joseph H.,Lazouski, Nikifar,Corbin, Nathan,Yang, Dengtao,Manthiram, Karthish
supporting information
p. 6413 - 6418
(2019/05/02)

Copper Hydride Catalyzed Enantioselective Synthesis of Axially Chiral 1,3-Disubstituted Allenes
The general enantioselective synthesis of axially chiral disubstituted allenes from prochiral starting materials remains a long-standing challenge in organic synthesis. Here, we report an efficient enantio- and chemoselective copper hydride catalyzed semireduction of conjugated enynes to furnish 1,3-disubstituted allenes using water as the proton source. This protocol is sufficiently mild to accommodate an assortment of functional groups including keto, ester, amino, halo, and hydroxyl groups. Additionally, applications of this method for the selective synthesis of monodeuterated allenes and chiral 2,5-dihydropyrroles are described.
Bayeh-Romero, Liela,Buchwald, Stephen L.
supporting information
p. 13788 - 13794
(2019/09/10)

N, C-Disubstituted Biarylpalladacycles as Precatalysts for ppm Pd-Catalyzed Cross Couplings in Water under Mild Conditions
Various monosubstitution and disubstitution patterns on the parent biarylamine skeleton characteristic of palladacycles, as well as the counterion effect, have been studied while looking for ways to increase the effectiveness of the catalyst formed under micellar catalysis conditions in water, with the goal of reducing the amount of Pd needed for coupling reactions. Several substituted palladacycles containing readily accessible ligands were chosen for evaluation. The results indicate that (1) preactivation of Pd(II) salts as precursors for Suzuki-Miyaura (SM) couplings via treatment with a reducing agent is not required; (2) reactions could be performed with approximately half the loading of Pd, relative to that previously required based on a combination of a Pd(II) salt and ligand; and (3) the most effective palladacycle precatalyst has been identified as that containing an isopropyl group on both an aryl ring and on nitrogen, together with the ligand EvanPhos and triflate as the counterion (P13). This precatalyst is also effective in other C-C bond-forming reactions, such as Heck and Sonogashira couplings. No organic solvents were needed for these processes, while the aqueous reaction medium could be recycled several times. A one-pot, four-step sequence involving Suzuki-Miyaura, reduction, alkylation, and acylation reactions highlights the potential for this precatalyst to maximize synthetic gain while minimizing costs and waste generation.
Thakore, Ruchita R.,Takale, Balaram S.,Gallou, Fabrice,Reilly, John,Lipshutz, Bruce H.
p. 11647 - 11657
(2019/11/29)

Efficient Homocoupling of Aryl- and Alkenylboronic Acids in the Presence of Low Loadings of [{Pd(μ-OH)Cl(IPr)} 2 ]
NHC-palladium(II) complex [{Pd(μ-OH)Cl(IPr)} 2 ] (IPr = bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) catalyzes the oxidative coupling of a broad spectrum of aryl- and alkenylboronic acids at loadings down to 5 ppm. At the concentration of 0.05 mol% the catalyst permits an efficient reaction under base-free conditions.
Ostrowska, Sylwia,Rogalski, Szymon,Lorkowski, Jan,Walkowiak, Jedrzej,Pietraszuk, Cezary
supporting information
p. 1735 - 1740
(2018/07/21)

Pd-catalyzed oxidative homo-coupling of acrylates and aromatic alkenes for the conjugated diene synthesis
We developed a bidentate monoanionic nitrogen ligand that was effective in the Pd-catalyzed oxidative homo-coupling reaction of acrylates and aromatic alkenes. In the presence of Pd(OAc)2/ligand several conjugated dienes were obtained in good yields with high stereoselectivities.
Zhu, Ting,Li, Zhen,Xiao, Fanhua,Duan, Wei-Liang
supporting information
p. 3238 - 3241
(2018/07/21)

M -C2B10H11HgCl/AgOTf-Catalyzed Reaction for Reductive Deoxygenation
A m -C2B10H11HgCl/AgOTf-catalyzed reaction of allyl silyl ethers with N -Boc- N ′-tosylhydrazine has been developed. Under mild conditions, the resulting allyl hydrazine products were transformed into naked alkenes in good yield. Furthermore, the used m -C2B10H11HgCl could be recovered quantitatively.
Yamasaki, Naoto,Kanno, Marina,Sakamoto, Kyohei,Kasai, Yusuke,Imagawa, Hiroshi,Yamamoto, Hirofumi
p. 169 - 175
(2018/03/26)

Nickel-Catalyzed system for the cross-coupling of alkenyl methyl ethers with grignard reagents under mild conditions
A nickel-catalyzed cross-coupling of alkenyl methyl ethers with Grignard reagents, under mild conditions, is described. These conditions allowed access to various stilbenes and heterocyclic stilbenic derivatives as well as to a potential anticancer agent DMU-212.
Hostier, Thomas,Neouchy, Zeina,Ferey, Vincent,Gomez Pardo, Domingo,Cossy, Janine
supporting information
p. 1815 - 1818
(2018/04/14)

Can the Ti(OiPr)4/nBuLi combination of reagents function as a catalyst for [2+2+2] alkyne cyclotrimerisation reactions?
Catalysis of the cyclotrimerisation of alkynes with the Ti(OiPr)4/nBuLi system was studied, leading to the development of a particularly convenient and reliable protocol. This method allows the [2+2+2] cycloaddition reaction to proceed within a few minutes under microwave conditions, with generally good selectivity from a variety of aromatic and aliphatic alkynes.
Siemiaszko, Gabriela,Six, Yvan
supporting information
p. 20219 - 20226
(2018/12/13)

A Copper-Catalyzed Reductive Defluorination of β-Trifluoromethylated Enones via Oxidative Homocoupling of Grignard Reagents
An efficient copper-catalyzed reductive defluorination of β-trifluoromethylated enones via an oxidative homocoupling of Grignard reagents is reported. The reaction proceeded smoothly with a wide range of substrates, including the ones bearing aromatic heterocycles, such as furyl and thienyl ring systems in high yields (80-92%, except one example) under mild conditions. This provides a practical method for synthesis of gem-difluoroolefin ketones. It is also worth noting that this homocoupling process of Grignard reagents using β-trifluoromethylated enones as oxidizing reagents is effective for both the Csp2-Csp2 and Csp3-Csp3 bond formations, including for substrates whose β-hydride elimination of the corresponding transition metal alkyl complex is particularly facile, affording coupling products with high yields (83-95%), simultaneously.
Wu, Xiaoting,Xie, Fang,Gridnev, Ilya D.,Zhang, Wanbin
supporting information
p. 1638 - 1642
(2018/03/23)

Palladium-Catalyzed Germylation of Aryl Bromides and Aryl Triflates Using Hexamethyldigermane
Palladium-catalyzed germylation of aryl bromides and aryl triflates using commercially available hexamethyldigermane is described. Optimized reaction conditions afforded various functionalized aryltrimethylgermanes, including drug-like molecules, in moderate to good yields, demonstrating the versatility of the presented protocols.
Komami, Narumi,Matsuoka, Keitaro,Yoshino, Tatsuhiko,Matsunaga, Shigeki
supporting information
p. 2067 - 2075
(2018/02/26)

O -Iodoxybenzoic acid mediated generation of aryl free radicals: Synthesis of stilbenes through C-C cross-coupling with β-nitrostyrenes
The generation of an aryl free radicals in the presence of nitrostyrenes through a combination of aryl hydrazines and o-iodoxybenzoic acid led to the synthesis of stilbenes by forming a new carbon-carbon bond after subsequent elimination of a nitrosyl radical. The symmetrical and unsymmetrical stilbenes with excellent E-selectivity were synthesized in good yields, with advantages of broad substrate scope and transition metal free, mild reaction conditions, under an open atmosphere in a short reaction time. A free radical mediated mechanism was postulated and supported by radical trapping experiments. Application of the developed methodology is demonstrated through a simple, two step synthesis of resveratrol, a valuable stilbenoid for anticancer and neurological studies via its prodrug E-1,3-dimethoxy-5-(4-methoxystyryl)benzene.
Wagh, Ganesh,Autade, Snehalata,Patil, Pravin C.,Akamanchi, Krishnacharya G.
p. 3301 - 3309
(2018/03/06)

Transition-Metal-Free Sulfuration/Annulation of Alkenes: Economical Access to Thiophenes Enabled by the Cleavage of Multiple C-H Bonds
A novel, atom economical, and transition-metal-free strategy for the synthesis of thiophenes from substituted buta-1-enes with potassium sulfide has been presented. The reaction achieves double C-S bond formations via cleavage of multiple C-H bonds and provides an efficient approach to access various functionalized thiophenes. Moreover, the strategy can also be used for the synthesis of thiophenes from 1,4-diaryl-1,3-dienes. Mechanistically, DMSO plays a role of oxidant and S3?- in situ generated from K2S is involved.
Chen, Liang,Min, Hao,Zeng, Weilan,Zhu, Xiaoming,Liang, Yun,Deng, Guobo,Yang, Yuan
supporting information
p. 7392 - 7395
(2019/01/03)

Copper(I)-Mediated Borofluorination of Alkynes
The electrophilic fluorination of N-heterocyclic carbene (NHC) copper(I) vinyls results in fluoroalkene formation. Alkynes can be converted to cis-(β-fluorovinyl)boronates by a reaction with an (NHC)copper(I) boryl generated in situ, followed by N-fluorobenzenesulfonimide (NFSI). This sequence gives rise to anti-Markovnikov fluorination products from terminal alkynes. Oxidation of a cis-(β-fluorovinyl)trifluoroboronate yields an α-fluoroketone, whereas a palladium-catalyzed Suzuki-Miyaura coupling yields a tetrasubstituted monofluoroalkene.
Jordan, Abraham J.,Thompson, Percie K.,Sadighi, Joseph P.
p. 5242 - 5246
(2018/09/12)

Intramolecular Desulfitative Coupling: Nickel-Catalyzed Transformation of Diaryl Sulfones into Biaryls via Extrusion of SO2
As a new transformation of organosulfur compounds, intramolecular desulfitative coupling of diaryl sulfones to the corresponding biaryls has been developed with the aid of nickel-NHC catalysts. This catalytic elimination of SO2 was also applicable to alkenyl aryl sulfone to furnish the corresponding alkenyl arene.
Takahashi, Fumiya,Nogi, Keisuke,Yorimitsu, Hideki
supporting information
p. 6601 - 6605
(2018/10/20)

One-pot Synthesis of 1,3-Butadiene and 1,6-Hexanediol Derivatives from Cyclopentadiene (CPD) via Tandem Olefin Metathesis Reactions
A novel tandem reaction of cyclopentadiene leading to high value linear chemicals via ruthenium catalyzed ring opening cross metathesis (ROCM), followed by cross metathesis (CM) is reported. The ROCM of cyclopentadiene (CPD) with ethylene using commercially available 2nd gen. Grubbs metathesis catalysts (1-G2) gives 1,3-butadiene (BD) and 1,4-pentadiene (2) (and 1,4-cyclohexadiene (3)) with reasonable yields (up to 24 % (BD) and 67 % (2+3) at 73 % CPD conversion) at 1–5 mol % catalyst loading in toluene solution (5 V% CPD, 10 bar, RT) in an equilibrium reaction. The ROCM of CPD with cis-butene diol diacetate (4) using 1.00 - 0.05 mol % of 3rd gen. Grubbs (1-G3) or 2nd gen. Hoveyda-Grubbs (1-HG2) catalysts loading gives hexa-2,4-diene-1,6-diyl diacetate (5), which is a precursor of 1,6-hexanediol (an intermediate in polyurethane, polyester and polyol synthesis) and hepta-2,5-diene-1,7-diyl diacetate (6) in good yield (up to 68 % or TON: 1180). Thus, convenient and selective synthetic procedures are revealed by ROCM of CPD with ethylene and 4 leading to BD and 1,6-hexanediol precursor, respectively, as key components of commercial intermediates of high-performance materials.
Turczel, Gábor,Kovács, Ervin,Csizmadia, Eszter,Nagy, Tibor,Tóth, Imre,Tuba, Robert
p. 4884 - 4891
(2018/09/25)

Ni-Catalyzed Reductive Coupling of Electron-Rich Aryl Iodides with Tertiary Alkyl Halides
This work illustrates the reductive coupling of electron-rich aryl halides with tertiary alkyl halides under Ni-catalyzed cross-electrophile coupling conditions, which offers an efficient protocol for the construction of all carbon quaternary stereogenic centers. The mild and easy-to-operate reaction tolerates a wide range of functional groups. The utility of this method is manifested by the preparation of cyclotryptamine derivatives, wherein successful incorporation of 7-indolyl moieties is of particular interest as numerous naturally occurring products are composed of these key scaffolds. DFT calculations have been carried out to investigate the proposed radical chain and double oxidative addition pathways, which provide useful mechanistic insights into the part of the reaction that takes place in solution.
Wang, Xuan,Ma, Guobin,Peng, Yu,Pitsch, Chloe E.,Moll, Brenda J.,Ly, Thu D.,Wang, Xiaotai,Gong, Hegui
supporting information
p. 14490 - 14497
(2018/11/02)

DINAPHTHOTHIOPHENE COMPOUNDS
The present invention generally relates to various dinaphthothiophene compounds and processes for preparing these compounds.
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Paragraph 0044; 0045

(2019/01/04)

Copper(I)-catalyzed stereoselective hydrogenation of 1,3-diynes and enynes
A stereoselective hydrogenation of 1,3-diynes with an air-stable copper(I)/N-heterocyclic carbene complex, [IPrCuOH], has been developed. The corresponding products, 1,3-dienes, are obtained in a stereoselective manner depending on their substitution pattern: Diaryl-diynes yield E,E-1,3-dienes, whereas dialkyl-diynes are converted to the corresponding Z,Z-1,3-dienes. Hydrogenation and deuteration experiments with enynes indicate that these are competent reaction intermediates in the hydrogenation of diynes.
Thiel, Niklas O.,Kemper, Sebastian,Teichert, Johannes F.
p. 5023 - 5028
(2017/07/27)

Mechanism of a Suzuki-Type Homocoupling Reaction Catalyzed by Palladium Nanocubes
The trans-2-phenylvinylboronic acid homocoupling reaction catalyzed by palladium nanocubes (Pd-NCs) was investigated by kinetics, spectroscopy, and poisoning experiments. The reaction was evidenced to be sensitive to the presence of the base, which acts synergistically with the substrate molecules and assists the leaching of Pd oxide (PdOx) species to the reaction medium. This species catalyzes the homocoupling reaction through the formation of Pd-Ox-B(OH)2R pretransmetalation intermediates, via coordination with the vinylboronic acid molecules, involving an oxo-palladium-type interaction. The reaction rate was not enhanced by the saturation of the reaction medium with O2, which is due to the oxidized nature of the Pd-NC surface.
Elias, Welman C.,Signori, Aline M.,Zaramello, Laize,Albuquerque, Brunno L.,De Oliveira, Daniela C.,Domingos, Josiel B.
p. 1462 - 1469
(2017/08/09)

Carbon-carbon bond forming reactions via Pd-catalyzed detellurative homocoupling of diorganyl tellurides
A simple and highly efficient method for the constructions of Csp-Csp, Csp2-Csp2 and Csp3-Csp3 bonds is reported. The symmetrical diaryl tellurides undergo detellurative homocouplings to afford symmetrical biaryl products. The reactions are carried out at ambient temperature using PdCl2 as a catalyst in the presence of Ag2O and Na2CO3. Similarly, the detellurative homocouplings of dibenzyl telluride and bis(phenylethynyl)telluride give bibenzyl and the conjugated diyne, respectively.
Zhang, Shaozhong,Kolluru, Lalitha,Vedula, Souseelya K.,Whippie, Drew,Jin, Jin
supporting information
p. 3594 - 3597
(2017/08/23)

Catalytic Dehydrogenative C-C Coupling by a Pincer-Ligated Iridium Complex
The pincer-iridium fragment (iPrPCP)Ir (RPCP = ?3-2,6-C6H3(CH2PR2)2) has been found to catalyze the dehydrogenative coupling of vinyl arenes to afford predominantly (E,E)-1,4-diaryl-1,3-butadienes. The eliminated hydrogen can undergo addition to another molecule of vinyl arene, resulting in an overall disproportionation reaction with 1 equiv of ethyl arene formed for each equivalent of diarylbutadiene produced. Alternatively, sacrificial hydrogen acceptors (e.g., tert-butylethylene) can be added to the solution for this purpose. Diarylbutadienes are isolated in moderate to good yields, up to ca. 90% based on the disproportionation reaction. The results of DFT calculations and experiments with substituted styrenes indicate that the coupling proceeds via double C-H addition of a styrene molecule, at β-vinyl and ortho-aryl positions, to give an iridium(III) metalloindene intermediate; this intermediate then adds a β-vinyl C-H bond of a second styrene molecule before reductively eliminating product. Several metalloindene complexes have been isolated and crystallographically characterized. In accord with the proposed mechanism, substitution at the ortho-aryl positions of the styrene precludes dehydrogenative homocoupling. In the case of 2,4,6-trimethylstyrene, dehydrogenative coupling of β-vinyl and ortho-methyl C-H bonds affords dimethylindene, demonstrating that the dehydrogenative coupling is not limited to C(sp2)-H bonds.
Wilklow-Marnell, Miles,Li, Bo,Zhou, Tian,Krogh-Jespersen, Karsten,Brennessel, William W.,Emge, Thomas J.,Goldman, Alan S.,Jones, William D.
p. 8977 - 8989
(2017/07/12)

Reductive Homocoupling of Organohalides Using Nickel(II) Chloride and Samarium Metal
A homocoupling method for organohalides and organosulfonates promoted by samarium metal and HMPA, and catalyzed by NiCl2 has been developed. Various organohalides (benzyl, aryl, heterocyclic, alkenyl and alkyl halides), α-haloacetophenones, and phenyl organosulfonates were tolerated, and the reaction afforded coupling products with high efficiency. Excellent chemoselectivity was exhibited between halides and other groups, such as ?COOH, ?NO2, halogen, heterocyclic ring, ester, and ketone groups. The stereoselectivity suggested that the reaction mechanism might involve an organosamarium species.
Liu, Yongjun,Xiao, Shuhuan,Qi, Yan,Du, Feng
p. 673 - 678
(2017/03/22)

Cyclobutene vs 1,3-Diene Formation in the Gold-Catalyzed Reaction of Alkynes with Alkenes: The Complete Mechanistic Picture
The intermolecular gold(I)-catalyzed reaction between arylalkynes and alkenes leads to cyclobutenes by a [2 + 2] cycloaddition, which takes place stepwise, first by formation of cyclopropyl gold(I) carbenes, followed by a ring expansion. However, 1,3-butadienes are also formed in the case of ortho-substituted arylalkynes by a metathesis-type process. The corresponding reaction of alkenes with aryl-1,3-butadiynes, ethynylogous to arylalkynes, leads exclusively to cyclobutenes. A comprehensive mechanism for the gold(I)-catalyzed reaction of alkynes with alkenes is proposed on the basis of density functional theory calculations, which shows that the two pathways leading to cyclobutenes or dienes are very close in energy. The key intermediates are cyclopropyl gold(I) carbenes, which have been independently generated by retro-Buchner reaction from stereodefined 1a,7b-dihydro-1H-cyclopropa[a]naphthalenes.
De Orbe, M. Elena,Amenós, Laura,Kirillova, Mariia S.,Wang, Yahui,López-Carrillo, Verónica,Maseras, Feliu,Echavarren, Antonio M.
p. 10302 - 10311
(2017/08/09)

Nickel-catalyzed N-vinylation of heteroaromatic amines via C-H bond activation
Here, we report a ligand- and reductant-free nickel-catalyzed N-vinylation of heteroaromatic amines using biorenewable p-cymene as a solvent. This unprecedented cross-coupling strategy has high functional group tolerance (halides, alkoxy, cyano, chiral motif, etc.) and proceeded via C-H bond activation.
Landge, Vinod G.,Rana, Jagannath,Subaramanian, Murugan,Balaraman, Ekambaram
supporting information
p. 6896 - 6900
(2017/09/01)

Synthesis of the 1,2-seco fusicoccane diterpene skeleton by Stille coupling reaction between the highly functionalized A and C ring segments of cotylenin A
1-Hydroxy-14-isopropyl-3β-methoxymethyl-7β,11β-dimethyl-3α-[((2-trimethylsilyl)ethoxy)methoxy]-1,2-secofusicocca-8,10(14)-dien-2-one, a highly functionalized 1,2-seco fusicoccane diterpene skeleton related to cotylenin A was synthesized in a convergent manner. The A ring segment, i. e., (1′R,2S, 2′E,5S)-2-methoxymethyl-5-[1′-methyl-3’-(trimethylstannyl)prop-2-enyl]-2-[((2″-trimethylsilyl)ethoxy)methoxy]cyclopentanone, was synthesized in 20.1% yield over 18 steps from known (S)-5-isopropenyl-2-methylcyclopent-1-enecarbaldehyde. This was coupled with the C ring segment, i. e., (R)-5-hydroxymethyl-2-isopropyl-5-methylcyclopent-1-en-1-yl trifluoromethylsulfonate, which was prepared according to our previous report. The Stille coupling reaction between alkenylstannane and sterically hindered triflate proceeded successfully in the presence of PEPPSI-SIPr (85%), and the total yield of the target molecule was 17.1% over the longest linear sequences (19 steps) from (S)-5-isopropenyl-2-methylcyclopent-1-enecarbaldehyde.
Kuwata, Kazuaki,Hanaya, Kengo,Higashibayashi, Shuhei,Sugai, Takeshi,Shoji, Mitsuru
p. 6039 - 6045
(2017/09/18)

Metathesis of renewable polyene feedstocks – Indirect evidences of the formation of catalytically active ruthenium allylidene species
Cross-metathesis (CM) of conjugated polyenes, such as 1,6-diphenyl-1,3,5-hexatriene (1) and α-eleostearic acid methyl ester (2) with several olefins, including 1-hexene, dimethyl maleate and cis-stilbene as model compounds has been carried out using (1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene)-dichloro(o-isopropoxyphenylmethylene)ruthenium (Hoveyda-Grubbs 2nd generation, HG2) catalyst. The feasibility of these reactions is demonstrated by the observed high conversions and reasonable yields. Thus, regardless of the relatively low electron density, =CH–CH= conjugated units of molecules, including compound 2 as a sustainable, non-foodstuff source, can be utilized as building blocks for the synthesis of various value-added chemicals via olefin metathesis. DFT-studies and the product spectrum of the self-metathesis of 1,6-diphenyl-1,3,5-hexatriene suggest that a Ru η1-allylidene complex is the active species in the reaction.
Kovács, Ervin,Sághy, Péter,Turczel, Gábor,Tóth, Imre,Lendvay, Gy?rgy,Domján, Attila,Anastas, Paul T.,Tuba, Róbert
supporting information
p. 213 - 217
(2017/09/12)

Synthesis of Unsymmetric Monosubstituted and Disubstituted Dinaphthothiophenes
Dinaphthothiophenes (DNTs) are a class of compounds with potential uses in organic semiconductors and the synthesis of unsymmetric catalysts. Symmetrical or asymmetrical addition of functional groups to the DNT structure may be desired for steric bulk in binaphthyl catalyst synthesis or tuning the electronic properties of semiconductors. Thus, versatility of functional group addition is a great asset in DNT synthesis. Until now, no versatile and concise methods for the synthesis of unsymmetrically substituted DNTs have been reported. Herein, we report three synthetic routes for the creation of three different classes of DNTs. Each route involves the successive addition of two functionalized styryl groups to a thiophene ring, followed by a photocyclization to form the desired asymmetric DNT. Various novel unsymmetrically monosubstituted and disubstituted dinaphtho[2,1-b:1′,2′-d]thiophenes, dinaphtho[1,2-b:1′,2′-d]thiophenes, and dinaphtho[1,2-b:2′,1′-d]thiophenes were synthesized from 2-bromothiophene,2,4-dibromothiophene, and 3,4-dibromothiophene in three or four steps. These methods can be used to synthesize a wide variety of unsymmetrically functionalized DNTs.
Throgmorton, John C.,Chintala, Satyanarayana M.,McCulla, Ryan D.
supporting information
p. 3682 - 3688
(2017/10/09)

Enantioselective Rhodium-Catalyzed Alkenylation of Aliphatic Imines
An efficient, enantioselective rhodium-catalyzed addition of potassium alkenyltrifluoroborates to N-nosyl aliphatic imines has been realized. Good reaction yields and excellent enantioselectivities (94-99% ee) were obtained for a variety of aliphatic imines and nucleophilic alkenyltrifluoroborates. An active rhodium-diene catalyst and the precise reaction condition control proved to be pivotal for success.
Qian, Xue-Wei,Xue, Ze-Jian,Zhao, Qian,Cui, Zhe,Chen, Ya-Jing,Feng, Chen-Guo,Lin, Guo-Qiang
supporting information
p. 5601 - 5604
(2017/10/25)