- A boron-oxygen transborylation strategy for a catalytic midland reduction
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The enantioselective hydroboration of ketones is a textbook reaction requiring stoichiometric amounts of an enantioenriched borane, with the Midland reduction being a seminal example. Here, a turnover strategy for asymmetric catalysis, boron.oxygen transb
- Nicholson, Kieran,Dunne, Joanne,DaBell, Peter,Garcia, Alexander Beaton,Bage, Andrew D.,Docherty, Jamie H.,Hunt, Thomas A.,Langer, Thomas,Thomas, Stephen P.
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p. 2034 - 2040
(2021/02/20)
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- Bimetal Cooperatively Catalyzed Arylalkynylation of Alkynylsilanes
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An unprecedented Pd/Rh cooperatively catalyzed arylalkynylation of alkynylsilanes was developed to merge an alkynylidene moiety with benzosilacycle. These silaarenes possess a particular aggregation-induced emission behavior. Mechanistic investigations demonstrate that the relay trimetallic transmetalation plays a pivotal role in governing this transformation.
- Chen, Xing,Li, Mengke,Liu, Zhipeng,Yang, Can,Xie, Haisheng,Hu, Xinwei,Su, Shi-Jian,Jiang, Huanfeng,Zeng, Wei
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supporting information
p. 6724 - 6728
(2021/09/08)
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- Silver Mediated Banert Cascade with Carbon Nucleophiles
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The Banert cascade of propargylic azides can be promoted by simple silver salts, and the triazafulvene intermediate can be intercepted by carbon nucleophiles. Various indoles (>25 examples, up to 92% yield) and electron-rich heterocycles were effective. T
- Alexander, Juliana R.,Kevorkian, Paul V.,Topczewski, Joseph J.
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supporting information
p. 3227 - 3230
(2021/05/05)
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- Intercepting the Banert cascade with nucleophilic fluorine: Direct access to α-fluorinated: N H-1,2,3-triazoles
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The treatment of propargylic azides with silver(i) fluoride in acetonitrile was found to yield α-fluorinated NH-1,2,3-triazoles via the Banert cascade. The reaction was regioselective and the products result from an initial [3,3] rearrangement. The reacti
- Alexander,Kevorkian,Topczewski
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supporting information
p. 5024 - 5027
(2021/05/28)
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- An efficient nanocluster catalyst for Sonogashira reaction
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Pd together with CuI has been well known as the catalyst towards Sonogashira reaction, which provides an effective route to functional alkynes. However, the achievement of high activity and selectivity of this catalytic system is still challenging in some cases. Illustrative examples include their low activity for aryl chloride substrates, and switched selectivity to oxidative coupling products in air atmosphere. In this work, a Cu-incorporated Au13 nanocluster [Au13Cu2(PPh3)6(SC2H4Ph)6]+[NO3]- (Au13Cu2) was designed and prepared in high yield via rapid synthesis. This atomically precise nanocluster shows the potential to be a novel catalytic system for Sonogashira reaction, featuring high activity and selectivity, as well as good recyclability even in air atmosphere.
- Chen, Cheng,Chen, Li,Li, Man-Bo,Luo, Gen,Lv, Qi-Long,Wu, Zhikun,Xu, Guo-Yong,Yang, Jinlong,Yang, Ying,Ye, Sun-Feng,Yuan, Jinyun
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p. 206 - 213
(2021/08/16)
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- Nickel-catalyzed asymmetric propargylic amination of propargylic carbonates with aniline derivatives
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A study for the development of the nickel-catalyzed highly enantioselective propargylic amination of propargylic carbonates with aniline derivatives is described. The reaction of internal alkyne-substituted propargylic carbonates with a series of aniline derivatives smoothly proceeded in DMSO using a combination of Ni(cod)2 and (R)-SEGPHOS as the catalyst to give the corresponding chiral propargylic amines in 61-93% yields with 91-97% ee (24 examples).
- Tsuji, Hiroaki,Shimizu, Yuka,Miyazaki, Yusuke,Kawatsura, Motoi
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supporting information
p. 1002 - 1005
(2021/05/19)
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- Efficient Synthesis of Polysubstituted Furans through a Base-Promoted Oxacyclization of (Z)-2-En-4-yn-1-ols
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An efficient base catalyzed oxacyclization of Z-enynols has been developed under transition metal-free reaction conditions, thus resulting in a variety of new di-, tri-, and tetra-substituted furans. This approach allowed us to obtain 32 new compounds. Furthermore, DFT calculations were realized to depict a relationship between the natural population analysis and experimental results with alkyl or aryl groups for the synthesis of 2-benzylfuran. A one-pot Sonogashira/oxacyclization approach offers a flexible, robust and efficient alternative to base catalyzed cyclization is also carried out.
- Hrizi, Asma,Thiery, Emilie,Romdhani-Younes, Moufida,Jacquemin, Johan,Thibonnet, Jér?me
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supporting information
p. 3798 - 3806
(2021/06/14)
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- Aromatic Aza-Claisen Rearrangement of Arylpropargylammonium Salts Generated in situ from Arynes and Tertiary Propargylamines
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The charge-accelerated aza-Claisen rearrangement of ammonium salts serves as a key step in the construction of complex nitrogen-containing molecules. However, much less attention has been paid to the aromatic aza-Claisen rearrangement than to the aliphatic one. Herein, we report an unprecedented aromatic aza-Claisen rearrangement of arylpropargylammonium salts, generated in situ from arynes and tertiary propargylamines, delivering structurally diverse 2-propargylanilines in moderate to good yields with high regioselectivity. This rearrangement proceeds in the absence of strong bases or transition metals, is compatible with moisture and air, tolerates a wide variety of functional groups, and is amenable to forming 11- to 13-membered heterocycles with a triple bond. The 2-propargylaniline products were treated with aluminum chloride in ethanol to afford multisubstituted indoles in moderate to excellent yields. Finally, a series of deuterium-labeling experiments was performed to elucidate the reaction mechanism.
- Han, Lu,Li, Sheng-Jun,Zhang, Xue-Ting,Tian, Shi-Kai
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supporting information
p. 3091 - 3097
(2021/01/21)
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- Unified Approach to Furan Natural Products via Phosphine-Palladium Catalysis
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Polyalkyl furans are widespread in nature, often performing important biological roles. Despite a plethora of methods for the synthesis of tetrasubstituted furans, the construction of tetraalkyl furans remains non-trivial. The prevalence of alkyl groups in bioactive furan natural products, combined with the desirable bioactivities of tetraalkyl furans, calls for a general synthetic protocol for polyalkyl furans. This paper describes a Michael–Heck approach, using sequential phosphine-palladium catalysis, for the preparation of various polyalkyl furans from readily available precursors. The versatility of this method is illustrated by the total syntheses of nine distinct polyalkylated furan natural products belonging to different classes, namely the furanoterpenes rosefuran, sesquirosefuran, and mikanifuran; the marine natural products plakorsins A, B, and D and plakorsin D methyl ester; and the furan fatty acids 3D5 and hydromumiamicin.
- Chen, Violet Yijang,Kwon, Ohyun
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supporting information
p. 8874 - 8881
(2021/03/17)
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- Synthesis of Highly Substituted Biaryls by the Construction of a Benzene Ring via in Situ Formed Acetals
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Herein, we present an interesting method for the construction of a benzene ring using propargylic alcohols and 1,3-dicarbonyls, which involves three new C-C bond formations via cascade alkylation, formylation, annulation, and aromatization to make substituted biaryls. This one-pot Br?nsted acid-promoted protocol utilizes the unique reactivity of the acetal formed under the reaction conditions. Alkynyl methyl ketones could be employed instead of 1,3-dicarbonyls as they are converted to 1,3-dicarbonyls by hydration under the reaction conditions.
- Balamurugan, Rengarajan,Manojveer, Seetharaman,Tarigopula, Chandrahas
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p. 11871 - 11883
(2021/09/13)
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- A sustainable access to ynones through laccase/TEMPO-catalyzed metal- and halogen-free aerobic oxidation of propargylic alcohols in aqueous medium
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Tuning laccase/TEMPO-catalyzed aerobic oxidation of secondary propargylic alcohols in aqueous media was accomplished in order to efficiently synthesize ynones. This study led to the formulation of an effective and sustainable catalytic method for the preparation of mono- and bis-substituted ynones compared with traditional oxidative methods.
- Silva, Alana B.V.,Silva, Emmanuel D.,dos Santos, Alcindo A.,Princival, Jefferson L.
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- Divergent Mechanisms of the Banert Cascade with Propargyl Azides
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Triazoles are privileged heterocycles for a variety of applications. The synthesis of 1H-triazoles can be accomplished by the Banert cascade from propargylic azides. Depending on the substrate and conditions, the Banert cascade can proceed by either a sigmatropic or prototropic mechanism. This report describes the first detailed kinetic analysis of the Banert cascade proceeding by both pathways including substituent effects and KIE. The analysis identified the inflection point in the divergent pathways, allowing future work to predict which Banert products are accessible.
- Alexander, Juliana R.,Packard, Mary H.,Hildebrandt, Alanna M.,Ott, Amy A.,Topczewski, Joseph J.
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p. 3174 - 3181
(2020/03/23)
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- Benzene-1,3,5-triyl Triformate (TFBen)-Promoted Palladium-Catalyzed Carbonylative Synthesis of 2-Oxo-2,5-dihydropyrroles from Propargyl Amines
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In this letter, we developed a palladium-catalyzed procedure for the cyclocarbonylation of propargyl amines. Benzene-1,3,5-triyl triformate (TFBen) has been explored as the CO source and also as the key promotor. Various substituted 2-oxo-dihydropyrroles were produced in a facile manner in good yields (up to 90%).
- Ying, Jun,Le, Zhengjie,Wu, Xiao-Feng
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supporting information
p. 194 - 198
(2020/01/03)
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- Synthesis of substituted benzo[: B] [1,4]oxazepine derivatives by the reaction of 2-aminophenols with alkynones
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We have developed a novel synthetic method accessing benzo[b][1,4]oxazepines that are one of the rare classes of benzoxazepine derivatives by reaction of 2-aminophenols with alkynones in 1,4-dioxane at 100 °C. A series of benzo[b][1,4]oxazepine derivatives can be prepared by using this synthetic protocol. Mechanistic experiments indicated that the hydroxy proton of the aminophenol could play a crucial role in the formation of an alkynylketimine intermediate that undergoes 7-endo-dig cyclization.
- Oshimoto, Kohei,Zhou, Biao,Tsuji, Hiroaki,Kawatsura, Motoi
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supporting information
p. 415 - 419
(2020/01/30)
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- Transition-Metal-Free Synthesis of Electron Rich 1,3-Dienes via Base Promoted Isomerization of Propargylic Ethers
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Herein, a novel and scalable synthesis of electron rich 1,3-dienes based on KOtBu mediated isomerization of propargylic ether derivatives was developed. This new process features easy handling reaction conditions, transition-metal-free isomerization, high isolated yields, and most of all, it could be used for modification of natural products at late stage functionalizations.
- Liu, Chunxiang,Deng, Guogang,Li, Xin,Xu, Yiren,Yu, Kaili,Chen, Wen,Zhang, Hongbin,Yang, Xiaodong
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supporting information
p. 483 - 487
(2020/01/25)
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- Nickel-Catalyzed Asymmetric Friedel-Crafts Propargylation of 3-Substituted Indoles with Propargylic Carbonates Bearing an Internal Alkyne Group
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The nickel-catalyzed highly enantioselective Friedel-Crafts propargylation of 3-substituted indoles with propargylic carbonates bearing an internal alkyne group was developed. A wide array of the propargylic carbonates as well as 3-substituted indoles can be applicable to the asymmetric nickel catalysis, providing the corresponding chiral C-3 propargylated indolenine derivatives bearing two vicinal chiral centers in up to 89% yield with up to >99% ee and 94:6 dr (24 examples).
- Miyazaki, Yusuke,Zhou, Biao,Tsuji, Hiroaki,Kawatsura, Motoi
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supporting information
p. 2049 - 2053
(2020/03/04)
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- DBU-Catalyzed Rearrangement of Secondary Propargylic Alcohols: An Efficient and Cost-Effective Route to Chalcone Derivatives
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A 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed rearrangement of diarylated secondary propargylic alcohols to give α,β-unsaturated carbonyl compounds has been developed. The typical 1,3-transposition of oxy functionality, characteristic of Mayer-Schuster rearrangements, is not observed in this case. A broad substrate scope, functional-group tolerance, operational simplicity, complete atom economy, and excellent yields are among the prominent features of the reaction. Additionally, the photophysical properties and crystal-structure-packing behavior of selected compounds were investigated and found to be of interest.
- De, Rimpa,Savarimuthu, Antony,Ballav, Tamal,Singh, Pijush,Nanda, Jayanta,Hasija, Avantika,Chopra, Deepak,Bera, Mrinal K.
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supporting information
p. 1587 - 1592
(2020/08/28)
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- Regioselective Iron-Catalysed Cross-Coupling Reaction of Aryl Propargylic Bromides and Aryl Grignard Reagents
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An iron-catalysed Kumada-type cross-coupling reaction between aryl substituted propargylic bromides and arylmagnesium reagents has been developed. Propargylic coupling products were the main or only outcome, and propargyl/allene regioselectivity was shown to depend on the electronic nature of the substituents on the triple bond of the substrate and on the arylmagnesium halide. Best selectivities were observed when electron donating substituents were present in either reagent. The process is stereoespecific, occurs with configuration inversion and no carbon-based radicals seem to be involved in the mechanism. (Figure presented.).
- Manjón-Mata, Inés,Quirós, M. Teresa,Bu?uel, Elena,Cárdenas, Diego J.
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supporting information
p. 146 - 151
(2019/12/11)
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- Kinetic Resolution of Propargylic Ethers via [2,3]-Wittig Rearrangement to Synthesize Chiral α-Hydroxyallenes
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An efficient kinetic resolution of propargyloxy dicarbonyl compounds via asymmetric [2,3]-Wittig rearrangement was achieved by using a chiral N,N′-dioxide/NiII complex catalyst. Various chiral α-allenyl alcohols were obtained in high enantioselectivities under mild conditions. The utility of this method was readily demonstrated in the asymmetric synthesis of the chiral 2,5-dihydrofuran derivative.
- Xu, Xi,Dong, Shunxi,Feng, Lili,Wang, Sijing,Liu, Xiaohua,Feng, Xiaoming
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supporting information
p. 2692 - 2696
(2020/03/30)
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- Chemoselective Hydroboration of Propargylic Alcohols and Amines Using a Manganese(II) Catalyst
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The first manganese-catalyzed hydroboration of propargylic alcohols and amines as well as internal alkynes is reported. High regio- and stereoselectivity is achieved by applying 2 mol % of a manganese precatalyst based on the readily accessible bis(imino)pyridine ligand and MnCl2 as metal source. Propargylic alcohols and amines, as well as symmetric internal alkynes, were efficiently converted into the corresponding functionalized alkenes, which can serve as important and valuable intermediates for further synthetic applications such as cross-coupling reactions.
- Brzozowska, Aleksandra,Zubar, Viktoriia,Ganardi, Ruth-Christine,Rueping, Magnus
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supporting information
p. 3765 - 3769
(2020/04/15)
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- Chemoselective Luche-Type Reduction of α,β-Unsaturated Ketones by Magnesium Catalysis
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The chemoselective reduction of α,β-unsaturated ketones by use of an economic and readily available Mg catalyst has been developed. Excellent yields for a wide range of ketones have been achieved under mild reaction conditions, short times, and low catalyst loadings (0.2-0.5 mol %).
- Jang, Yoon Kyung,Magre, Marc,Rueping, Magnus
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p. 8349 - 8352
(2019/10/16)
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- Phosphine-Catalyzed Intermolecular Annulations of Fluorinated ortho-Aminophenones with Alkynones – The Switchable [4+2] or [4+2]/[3+2] Cycloaddition
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A phosphine-catalyzed intermolecular annulation reaction of functionalized ortho-aminoacetophenones with alkynones has been disclosed in this paper. A variety of 2-alkynylquinolines and benzo-fused indolizine were selectively afforded in moderate to good yields at different reaction temperatures and with different phosphine catalysts via the in situ generated zwitterionic intermediate derived from alkynone and phosphine. (Figure presented.).
- Zhang, Yanshun,Sun, Yaoliang,Wei, Yin,Shi, Min
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supporting information
p. 2129 - 2135
(2019/03/13)
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- Asymmetric Propargylic Radical Cyanation Enabled by Dual Organophotoredox and Copper Catalysis
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The first asymmetric propargylic radical cyanation was realized through a dual photoredox and copper catalysis. An organic photocatalyst serves to both generate propargyl radicals and oxidize Cu(I) species to Cu(II) species. A chiral Cu complex functions as an efficient organometallic catalyst to resemble the propargyl radical and cyanide in an enantio-controlled manner. Thus, a diverse range of optically active propargyl cyanides were produced with high reaction efficiency and enantioselectivities (28 examples, 57-97% yields and 83-98% ee). Moreover, mechanistic investigations including experiments and density functional theory calculations were performed to illustrate on the reaction pathway and stereochemical results.
- Lu, Fu-Dong,Liu, Dan,Zhu, Lei,Lu, Liang-Qiu,Yang, Qian,Zhou, Quan-Quan,Wei, Yi,Lan, Yu,Xiao, Wen-Jing
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supporting information
p. 6167 - 6172
(2019/04/17)
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- Stereoselective Modification of N-(α-Hydroxyacyl)-glycinesters via Palladium-Catalyzed Allylic Alkylation
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N-(α-Hydroxyacyl)-glycinesters can be used as excellent nucleophiles in Pd-catalyzed allylic alkylation. The method allows for the stereoselective introduction of a wide range of side chains, including highly functionalized ones. Both diastereomers can be accessed through variation of the reaction conditions. Furthermore, the use of stannylated carbonates introduces vinylstannane motifs, which are eligible for subsequent C-C coupling reactions.
- Horn, Alexander,Kazmaier, Uli
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supporting information
p. 4595 - 4599
(2019/06/27)
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- Controllable chemoselectivity in the coupling of bromoalkynes with alcohols under visible-light irradiation without additives: Synthesis of propargyl alcohols and α-ketoesters
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The chemoselectivity of visible-light-induced coupling reactions of bromoalkynes with alcohols can be controlled by simple changes to the reaction atmosphere (N2 or O2). A N2 atmosphere favours propargyl alcohols via a direct C-C coupling process, whereas an O2 atmosphere results in the generation of α-ketoesters through the oxidative CC/C-O coupling pathway.
- Ni, Ke,Meng, Ling-Guo,Ruan, Hongjie,Wang, Lei
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supporting information
p. 8438 - 8441
(2019/07/22)
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- Bi(OTf)3 catalyzed synthesis of acyclic β-sulfanyl ketones via a tandem Meyer-Schuster rearrangement/conjugate addition reaction
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A new strategy to prepare acyclic β-carbonyl thioethers from propargyl alcohols and sulfur nucleophiles is reported. The investigation of the reaction substrates scope indicated that primary 3-aryl propargyl alcohols and thiols underwent the transformation smoothly. The reaction probably proceeded a Bi(OTf)3-catalyzed tandem Meyer-Schuster rearrangement of 3-aryl propargyl alcohol, followed by a thiol Michael conjugate addition of thiols to in situ generated α, β-unsaturated ketones. The method was 100% atom economic, high-yielding, and easy to handle, making it a valuable method for the construction of β-carbonyl sulfides.
- Wang, Yuan,Yin, Yan,Zhang, Qinglin,Pan, Wanyong,Guo, Huifeng,Pei, Keke
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supporting information
p. 2030 - 2034
(2019/07/03)
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- Site-Selective α-Alkoxyl Alkynation of Alkyl Esters Mediated by Boryl Radicals
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A novel method for site-selective C-H functionalization of ethyl acetate mediated by pyridine-boryl radicals is presented, delivering a variety of 4-phenylbut-3-yn-2-yl acetate derivatives under mild conditions. A distinguishing feature of this reaction i
- Guo, Ao,Han, Jia-Bin,Zhu, Lei,Wei, Yin,Tang, Xiang-Ying
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supporting information
p. 2927 - 2931
(2019/04/17)
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- Synthesis of benzoxazoles via the copper-catalyzed hydroamination of alkynones with 2-aminophenols
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We describe herein the synthetic method to benzoxazole derivatives via the copper-catalyzed hydroamination of alkynones with 2-aminophenols. The method produced a wide variety of functionalized benzoxazole derivatives in good yields. Preliminary mechanistic experiments revealed that the reaction would proceed through the copper-catalyzed hydroamination of alkynones and the sequential intramolecular cyclization of β-iminoketones/elimination of acetophenone promoted by the copper catalyst.
- Oshimoto, Kohei,Tsuji, Hiroaki,Kawatsura, Motoi
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supporting information
p. 4225 - 4229
(2019/05/10)
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- Nickel-Catalyzed Directed Hydroarylation of Alkynes with Boronic Acids
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A regio- and stereoselective nickel-catalyzed hydroarylation of alkynes using propargylic carbamates as directing groups has been developed. The reaction proceeds under mild reaction conditions using arylboronic acids in the absence of base. A range of heterocycles and functional groups are tolerated under the reaction conditions, providing high yields of trisubstituted alkenes with control of olefin geometry.
- Hanna, Luke E.,Konev, Mikhail O.,Jarvo, Elizabeth R.
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supporting information
p. 184 - 187
(2018/12/05)
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- Metal-Free Regioselective Chloroazidation of Internal Alkynes
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A metal-free, room temperature protocol for the regioselective chloroazidation of internal alkynes is disclosed. The reactions of internal alkynes with trimethylsilyl azide (TMSN3) in the presence of 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) afforded the corresponding chloroazidoalkenes in good yields. This reaction has good functional group tolerance and is operationally simple.
- Huang, Bin,Liffert, Raphael,Linden, Anthony,Gademann, Karl
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supporting information
p. 981 - 984
(2019/01/04)
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- Lewis-base-catalysed selective reductions of ynones with a mild hydride donor
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Ynones are efficiently reduced with a mild hydride donor in the presence of a catalytic amount of nucleophilic phosphines. The reactions are selective 1,2-reductions that give propargyl alcohols in yields of up to 96%. It is proposed that success in these reactions depends on the activation of ynones by a Lewis base catalyst. A protic additive plays a key role in suppressing the undesired reaction pathways and accelerating the 1,2-reductions.
- Sch?mberg,Zi,Vilotijevic
-
supporting information
p. 3266 - 3269
(2018/04/05)
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- Expanding the Substrate Specificity of Thermoanaerobacter pseudoethanolicus Secondary Alcohol Dehydrogenase by a Dual Site Mutation
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Here, we report the asymmetric reduction of selected phenyl-ring-containing ketones by various single- and dual-site mutants of Thermoanaerobacter pseudoethanolicus secondary alcohol dehydrogenase (TeSADH). The further expansion of the size of the substrate binding pocket in the mutant W110A/I86A not only allowed the accommodation of substrates of the single mutants W110A and I86A within the expanded active site but also expanded the substrate range of the enzyme to ketones bearing two sterically demanding groups (bulky–bulky ketones), which are not substrates for the TeSADH single mutants. We also report the regio- and enantioselective reduction of diketones with W110A/I86A TeSADH and single TeSADH mutants. The double mutant exhibited dual stereopreference to generate the Prelog products most of the time and the anti-Prelog products in a few cases.
- Musa, Musa M.,Bsharat, Odey,Karume, Ibrahim,Vieille, Claire,Takahashi, Masateru,Hamdan, Samir M.
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p. 798 - 805
(2018/02/21)
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- Trans -Hydroboration vs. 1,2-reduction: Divergent reactivity of ynones and ynoates in Lewis-base-catalyzed reactions with pinacolborane
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Ynones and ynoates react with pinacolborane in a divergent manner in the presence of nucleophilic phosphine catalysts. Ynones are transformed to the corresponding propargyl alcohols in good yields with high regio- and chemoselectivity. Ynoates undergo highly regio- and stereoselective trans-hydroboration to produce E-vinylboronates. Impressive divergence in reactivity of ynones and ynoates can be traced back to the mechanistic aspects of 1,2-reduction and trans-hydroboration. A comparative analysis of the two pathways paints a complex picture in which different reaction rates control selectivity in these seemingly unrelated processes and explains how sufficiently acidic protons in the reaction mixtures can be used to steer the selectivity in different directions.
- Zi, You,Sch?mberg, Fritz,Seifert, Fabian,G?rls, Helmar,Vilotijevic, Ivan
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supporting information
p. 6341 - 6349
(2018/09/10)
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- DBU-promoted carbonylative synthesis of 1,3-oxathiolan-2-ones from propargylic alcohols with TFBen as the CO source
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A DBU-promoted carbonylative cyclization of propargylic alcohols with sulfur was developed. Various 1,3-oxathiolan-2-ones were produced in 61-98% yields under mild conditions in the absence of metal catalysts. TFBen (benzene-1,3,5-triyl triformate) as an efficient and solid CO surrogate and S8 as an ideal sulfur source were employed and incorporated.
- Ying, Jun,Zhou, Chao,Wu, Xiao-Feng
-
supporting information
p. 1065 - 1067
(2018/02/22)
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- Harnessing Nucleophilicity of Allenol Ester with p-Quinone Methides via Gold Catalysis: Application to the Synthesis of Diarylmethine-Substituted Enones
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A gold(I)-catalyzed protocol for intermolecular 1,6-conjugate addition of nucleophilic allenol ester generated in situ through [3,3]-sigmatropic rearrangement with p-quinone methides (p-QMs) has been developed. The gold catalyst plays a dual role by the acid-triggered activation of alkynes and at the same time as a Lewis acid for activation of p-QMs toward nucleophilic attack. This method enables rapid access to a wide range of densely functionalized diarylmethine-substituted enones, a Morita-Baylis-Hillman (MBH) product with high selectivity, excellent yields, and broad substrate scope.
- Sharma, Brijesh M.,Rathod, Jayant,Gonnade, Rajesh G.,Kumar, Pradeep
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p. 9353 - 9363
(2018/06/29)
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- Phosphine-mediated partial reduction of alkynes to form both (E)- and (Z)-alkenes
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A mild, phosphine-mediated partial reduction of alkynyl carbonyls to the corresponding alkenes was developed. Tuning of the reaction conditions led to either the (E)- or (Z)-diastereomer with high selectivity. A range of alkynyl esters, amides, and ketones were reduced to form alkenes in good to high yields and with excellent functional group tolerance.
- Pierce, Brett M.,Simpson, Brittany F.,Ferguson, Kane H.,Whittaker, Rachel E.
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supporting information
p. 6659 - 6662
(2018/09/29)
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- Iron-Catalyzed Hydroborylative Cyclization of 1,6-Enynes
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We report first Fe-catalyzed hydroborylative cyclization reaction. The process provides one C?C and one C?B bond in a single operation and shows a wide scope, allowing the formation of carbo- and heterocycles containing a homoallylic boryl unit that can b
- Cabrera-Lobera, Natalia,Rodríguez-Salamanca, Patricia,Nieto-Carmona, Juan C.,Bu?uel, Elena,Cárdenas, Diego J.
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supporting information
p. 784 - 788
(2017/11/29)
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- Iron-Catalyzed Coupling of Propargyl Bromides and Alkyl Grignard Reagents
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An iron-catalyzed Kumada-type cross-coupling reaction of propargyl halides with alkylmagnesium reagents is described. The reaction is fast, takes place in smooth conditions, tolerates several functional groups that would be able to react with the Grignard reagent, and may afford either allene or propargyl coupling derivatives. Factors involved in the observed regioselectivity have been studied.
- Domingo-Legarda, Pablo,Soler-Yanes, Rita,Quirós-López, M. Teresa,Bu?uel, Elena,Cárdenas, Diego J.
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supporting information
p. 4900 - 4904
(2018/09/10)
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- Nickel(II)-Catalyzed Asymmetric Propargyl [2,3] Wittig Rearrangement of Oxindole Derivatives: A Chiral Amplification Effect
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A highly enantioselective [2,3] Wittig rearrangement of oxindole derivatives was realized by using a chiral N,N′-dioxide/NiII complex as the catalyst under mild reaction conditions. A strong chiral amplification effect was observed, and allowed access to chiral 3-hydroxy 3-substituted oxindoles bearing allenyl groups in high yields and enantioselectivities (up to 92 % ee) by using a ligand with only 15 % ee. A reasonable explanation was given based on the experimental investigations and X-ray crystal structures of enantiomerically pure and racemic catalysts. Moreover, the first catalytic kinetic resolution of racemic oxindole derivatives by a [2,3] Wittig rearrangement was realized with high efficiency and stereoselectivity.
- Xu, Xi,Zhang, Jianlin,Dong, Shunxi,Lin, Lili,Lin, Xiaobin,Liu, Xiaohua,Feng, Xiaoming
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supporting information
p. 8734 - 8738
(2018/07/14)
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- Gold(III)-Catalyzed Regioselective Oxidation/Cycloisomerization of Diynes: An Approach to Fused Furan Derivatives
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The first gold(III)-catalyzed regioselective oxidation/cycloisomerization of diynes 1 with pyridine N-oxide as the oxidant was developed, providing a range of synthetically valuable and useful fused furan derivatives 3 in moderate to good yields. Control experiments and the confirmation structure of minor products 5 suggest that this chemistry was a concerted gold(III)-catalyzed oxidation/SN2′-type addition/cyclization process via a β-gold vinyloxypyridinium intermediate and a putative vinyl cation intermediate.
- Li, Jian,Xing, Hong-Wen,Yang, Fang,Chen, Zi-Sheng,Ji, Kegong
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supporting information
p. 4622 - 4626
(2018/08/07)
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- On the Distribution of Linear versus Angular Naphthalenes in Aromatic Tetradehydro-Diels–Alder Reactions – Effect of Linker Structure and Steric Bulk
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We report here a systematic study of the aromatic tetradehydro-Diels–Alder (Ar-TDDA) reaction to elucidate the factors that have significant effects on the distribution of linear and angular naphthalene products. Two factors were studied, that is, the nat
- Chinta, Bhavani Shankar,Baire, Beeraiah
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supporting information
p. 3381 - 3385
(2017/06/29)
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- Sonogashira reaction using arylsulfonium salts as cross-coupling partners
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Triarylsulfonium, alkyl- and fluoroalkyl(diaryl)-sulfonium, and aryl(dialkyl)sulfonium triflates are successfully used as a new family of cross-coupling participants in the Sonogashira reaction as aryldiazonium, diaryliodonium, and tetraphenylphosphonium salts. It was found that terminal alkynes reacted mildly with triarylsulfonium or (2,2,2-trifluoroethyl)diphenylsulfonium triflate at room temperature under Pdand Cu-cocatalysis to give the corresponding arylalkynes in up to >99% yield. This protocol represents the first use of arylsulfonium salts as cross-coupling partners in the Pd/Cu-catalyzed Sonogashira reaction.
- Tian, Ze-Yu,Wang, Shi-Meng,Jia, Su-Jiao,Song, Hai-Xia,Zhang, Cheng-Pan
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p. 5454 - 5457
(2017/11/06)
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- Fe(OTf)3-catalyzed tandem Meyer-Schuster rearrangement/intermolecular hydroamination of 3-aryl propargyl alcohols for the synthesis of acyclic β-Aminoketones
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Fe(OTf)3-catalyzed synthesis of acyclic β-aminoketones from 3-aryl propargyl alcohols and nitrogen nucleophiles were investigated. Results showed that propargyl alcohols without bulky groups α to the hydroxyl group underwent the transformation smoothly. Sulphonamides exhibited the higher reactivity than amides as the nitrogen nucleophiles and the transformation of acyclic β-aminoketones were finished in shorter reaction time and higher yields. Finally, racemic fluoxetine was efficiently accessed with the present reaction as the first step. This novel synthesis of acyclic β-aminoketones probable proceeded a Fe(OTf)3-catalyzed Meyer-Schuster rearrangement of 3-aryl propargyl alcohols, followed by a intermolecular hydroamination between nitrogen nucleophiles and α, β-unsaturated ketones.
- Tao, Ruiheng,Yin, Yan,Duan, Yongbin,Sun, Yuxing,Sun, Yue,Cheng, Fengkai,Pan, Jinpeng,Lu, Cheng,Wang, Yuan
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p. 1762 - 1768
(2017/03/08)
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- Photoinduced Gold-Catalyzed Domino C(sp) Arylation/Oxyarylation of TMS-Terminated Alkynols with Arenediazonium Salts
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A selective and convenient synthesis of tri- and tetrasubstituted α,β-unsaturated ketones, as well as 2,3-diarylbenzofurans has been developed with the aid of light and taking advantage of a cooperative gold/photoredox-catalyzed 2-fold arylation reaction of TMS-terminated alkynols. The reaction of 3-(trimethylsilyl)prop-2-yn-1-ols was competent to generate diarylated α,β-unsaturated ketones; whereas the photoredox sequence involving 2-[(trimethylsilyl)ethynyl]phenol exclusively afforded 2,3-diarylbenzofurans. The reaction of terminal alkynes proceeded in poor yields while the use of bulkier silyl groups, such as TIPS, resulted unproductive. Apparently, the C(sp) arylation reaction is the first event on the domino bis-arylative sequence. These results could be explained through the intermediation of arylgold(III) species and several single electron transfer processes.
- Alcaide, Benito,Almendros, Pedro,Busto, Eduardo,Lázaro-Milla, Carlos
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p. 2177 - 2186
(2017/02/26)
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- NiICatalyzes the Regioselective Cross-Coupling of Alkylzinc Halides and Propargyl Bromides to Allenes
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We describe the unprecedented formation of allenes by Ni-catalyzed cross-coupling of propargyl bromides with alkylzinc halides. The reaction regioselectivity is complementary to the previously reported formation of propargyl-coupled compounds. Experiments
- Soler-Yanes, Rita,Arribas-álvarez, Iván,Guisán-Ceinos, Manuel,Bu?uel, Elena,Cárdenas, Diego J.
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supporting information
p. 1584 - 1590
(2017/02/10)
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- Gold-catalyzed Fluorination of Alkynyl Esters and Ketones: Efficient Access to Fluorinated 1,3-Dicarbonyl Compounds
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We developed an efficient synthesis of 2-fluoro-1,3-dicarbonyl compounds using readily available alkynyl ketones or esters as starting material. The key step is the insertion of hydrogen fluoride (HF) to the gold carbene intermediate generated from cationic gold catalyzed addition of N-oxides to alkynyl ketones or esters. This method gives excellent chemical yields and regioselectivity with good functional group tolerance. (Figure presented.).
- Zeng, Xiaojun,Lu, Zhichao,Liu, Shiwen,Hammond, Gerald B.,Xu, Bo
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supporting information
p. 4062 - 4066
(2017/11/30)
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- One-Pot Synthesis of Polysubstituted Imidazoles via Sequential Staudinger/aza-Wittig/Ag(I)-Catalyzed Cyclization/Isomerization
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A new one-pot preparation of polysubstituted imidazoles by a Staudinger/aza-Wittig/Ag(I)-catalyzed cyclization/isomerization has been developed. The easily accessible propargylazide derivatives reacted with triphenylphosphine, isocyanates, and amines sequ
- Xiong, Jun,Wei, Xiao,Liu, Zi-Ming,Ding, Ming-Wu
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p. 13735 - 13739
(2017/12/26)
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- Dual enzymatic dynamic kinetic resolution by Thermoanaerobacter ethanolicus secondary alcohol dehydrogenase and Candida antarctica lipase B
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The immobilization of Thermoanaerobacter ethanolicus secondary alcohol dehydrogenase (TeSADH) using sol-gel method enables its use to racemize enantiopure alcohols in organic media. Here, we report the racemization of enantiopure phenyl-ring-containing secondary alcohols using xerogel-immobilized W110A TeSADH in hexane rather than the aqueous medium required by the enzyme. We further showed that this racemization approach in organic solvent was compatible with Candida antarctica lipase B (CALB)-catalyzed kinetic resolution. This compatibility, therefore, allowed a dual enzymatic dynamic kinetic resolution of racemic alcohols using CALB-catalyzed kinetic resolution and W110A TeSADH-catalyzed racemization of phenyl-ring-containing alcohols.
- Karume, Ibrahim,Musa, Musa M.,Bsharat, Odey,Takahashi, Masateru,Hamdan, Samir M.,El Ali, Bassam
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p. 96616 - 96622
(2016/10/25)
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- Catalytic α-Allylation of Enones with Alcohols via [Gold(I)]-Mediated [3,3]-Sigmatropic Rearrangement of Propargylic Carboxylates
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The site-selective α-allylic alkylation of enones with alcohols via gold-triggered formation of nucleophilic allenoates by means of [3,3]-sigmatropic rearrangements of propargylic carboxylates is reported. A range of α-alkylated enones is obtained in high yields in the presence of the gold complex [JohnPhosAu(ACN)]SbF6 (2 mol%) as the promoting agent. Examples of allylation/Friedel-Crafts alkylation sequences are also provided, delivering densely functionalized dihydroindenes and dihydrobenzo[7]annulenes in a one-pot procedure in moderate yields. The role of the Br?nsted acidity (i.e., pivalic acid) delivered during the reaction course in assisting the formation of carbocationic intermediates is documented.
- Manoni, Elisabetta,Daka, Mario,Mastandrea, Marco M.,Nisi, Assunta De,Monari, Magda,Bandini, Marco
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supporting information
p. 1404 - 1409
(2016/05/19)
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- Sonogashira coupling catalyzed by the Cu(Xantphos)I–Pd(OAc)2system
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An efficient Pd(OAc)2/Cu(Xantphos)I system for Sonogashira coupling is disclosed. Aryl bromides/iodides and electron-poor aryl chlorides were suitable for this reaction. The experimental results suggest that Cu(Xantphos)I plays a unique role in which the phosphine ligand coordinates with copper.
- Liu, Meilin,Ye, Mingyan,Xue, Yeye,Yin, Guodong,Wang, Dunjia,Huang, Jinkun
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supporting information
p. 3137 - 3139
(2016/07/06)
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