Mn(III)-Mediated Facile Access to Polysubstituted α-Naphthols from β-Keto Ester Derivatives and Terminal Alkynes

The direct iminoalkynylation of unactivated olefins with terminal alkynes is achieved for the first time by nickel-catalyzed cascade iminyl-radical cyclization/Sonogashira-type coupling of γ,δ-unsaturated oxime esters under mild conditions. This transformation...

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Enantioenriched Quaternary α-Pentafluoroethyl Derivatives of Alkyl 1-Indanone-2-Carboxylates

10.26434/chemrxiv.12102678 ◽

2020 ◽

Author(s):

Albert Granados ◽

Anna Balleteros ◽

Adelina Vallribera

Keyword(s):

Hypervalent Iodine ◽

Catalytic Method ◽

Quaternary Centers ◽

Mild Conditions ◽

Reaction Proceeds ◽

Mechanistic Investigations ◽

Derivatives Of

An electrophilic enantioselective catalytic method for the a-pentafluoroethylation of alkyl 1-indanone-2-carboxylates is described. Under the use of La(OTf)3 in combination with (S,R)-indanyl-pybox ligand good results in terms of yield and enantioselectivities were achieved (up to 89% ee). The reaction proceeds under mild conditions leading to the formation of enantioenriched quaternary centers. This methodology uses an hypervalent iodine(III)-CF2CF3 reagent and mechanistic investigations are consistent with the involvement of a radical pathway.

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Visible-Light-Promoted Radical Cyclization of N-Arylvinylsulfonamides: Synthesis of CF3/CHF2/CH2CF3-Containing 1,3-Dihydrobenzo[c]isothiazole 2,2-Dioxide Derivatives

Synthesis ◽

10.1055/s-0040-1720921 ◽

2021 ◽

Author(s):

Devaiah Vytla ◽

Kumargurubaran Kaliyaperumal ◽

Rajeswari Velayuthaperumal ◽

Parinita Shaw ◽

Raj Gautam ◽

...

Keyword(s):

Visible Light ◽

Radical Cyclization ◽

Mild Conditions ◽

Highly Efficient ◽

Reaction Proceeds ◽

High Yields

AbstractA photocatalyzed and highly efficient trifluoromethylation of N-arylvinylsulfonamides using commercially available CF3SO2Cl as the trifluoromethyl radical source under blue LEDs is reported. The reaction proceeds through radical cyclization under mild conditions. An investigation of the substrate scope is performed to establish a general, synthetically useful protocol for the synthesis of novel trifluoromethylated 1,3-dihydrobenzo[c]isothiazole 2,2-dioxides in moderate to high yields. This method is also successfully applied for the synthesis of difluoromethylated and trifluoroethylated 1,3-dihydrobenzo[c]isothiazole 2,2-dioxides in good to excellent yields.

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Acetic Acid-Promoted Rhodium(III)-Catalyzed Hydroarylation of Terminal Alkynes

Synlett ◽

10.1055/s-0037-1611780 ◽

2019 ◽

Vol 30 (08) ◽

pp. 932-938 ◽

Cited By ~ 4

Author(s):

Chang-Lin Duan ◽

Xing-Yu Liu ◽

Yun-Xuan Tan ◽

Rui Ding ◽

Shiping Yang ◽

...

Keyword(s):

Acetic Acid ◽

Functional Group ◽

Bond Activation ◽

Side Reactions ◽

Terminal Alkynes ◽

Terminal Alkyne ◽

Mechanistic Studies ◽

Mild Conditions ◽

Reaction Proceeds

Rhodium(III)-catalyzed hydroarylation of terminal alkynes has not previously been achieved because of the inevitable oligomerization and other side reactions. Here, we report a novel Cp*Rh(III)-catalyzed hydroarylation of terminal alkynes in acetic acid as solvent to facilitate the C–H bond activation and subsequent transformations. This reaction proceeds under mild conditions, providing an effective approach to the synthesis of alkenylated heterocycles in high to excellent yields (31–99%) with a broad substrate scope (37 examples) and good functional-group compatibility. In this transformation, the loading of the alkyne can be reduced to 1.2 equivalents, which indicates the significant role of HOAc in lowering the reaction temperature and suppressing the oligomerization of the terminal alkyne. Preliminary mechanistic studies are also presented.

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Selective Manganese-Catalyzed Semihydrogenation of Alkynes with in-situ Generated H2 from KBH4 and Methanol

10.33774/chemrxiv-2021-bk2t8 ◽

2021 ◽

Author(s):

Ronald Farrar-Tobar ◽

Stefan Weber ◽

Zita Csendes ◽

Antonio Ammaturo ◽

Sarah Fleissner ◽

...

Keyword(s):

Reaction Mechanism ◽

Dft Calculations ◽

Functional Groups ◽

Hydrogen Gas ◽

Terminal Alkynes ◽

Deuterium Labelling ◽

Reaction Proceeds ◽

Mechanistic Investigations

The selective semihydrogenation of alkynes with the Mn(I) alkyl catalyst fac-[Mn(dippe)(CO)3(CH2CH2CH3)] (dippe = 1,2-bis(di-iso-propylphosphino)ethane) as pre-catalyst is described. Hydrogen gas required for the hydrogenation is generated in situ upon alcoholysis of KBH4 with methanol. A series of aryl-aryl, aryl-alkyl, alkyl-alkyl and terminal alkynes were readily hydrogenated to yield E-alkenes in good to excellent isolated yields. The reaction proceeds at 90°C with catalyst loadings of 0.5 -2 mol%. The implemented protocol tolerates a variety of electron donating and electron withdrawing functional groups including halides, phenols, nitriles, unprotected amines and heterocycles. The reaction can be upscaled to the gram scale. Mechanistic investigations including deuterium labelling studies and DFT calculations were undertaken to provide a reasonable reaction mechanism showing that initially formed Z-isomer undergoes fast isomerization to afford the thermodynamically more stable E-isomer.

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Enantioenriched Quaternary α-Pentafluoroethyl Derivatives of Alkyl 1-Indanone-2-Carboxylates

10.26434/chemrxiv.12102678.v1 ◽

2020 ◽

Author(s):

Albert Granados ◽

Anna Balleteros ◽

Adelina Vallribera

Keyword(s):

Hypervalent Iodine ◽

Catalytic Method ◽

Quaternary Centers ◽

Mild Conditions ◽

Reaction Proceeds ◽

Mechanistic Investigations ◽

Derivatives Of

An electrophilic enantioselective catalytic method for the a-pentafluoroethylation of alkyl 1-indanone-2-carboxylates is described. Under the use of La(OTf)3 in combination with (S,R)-indanyl-pybox ligand good results in terms of yield and enantioselectivities were achieved (up to 89% ee). The reaction proceeds under mild conditions leading to the formation of enantioenriched quaternary centers. This methodology uses an hypervalent iodine(III)-CF2CF3 reagent and mechanistic investigations are consistent with the involvement of a radical pathway.

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Nickel-Catalyzed Asymmetric Reductive Cross-Coupling of α-Chloroesters with (Hetero)Aryl Iodides

Chemical Science ◽

10.1039/d1sc00822f ◽

2021 ◽

Author(s):

Travis DeLano ◽

Sara Dibrell ◽

Caitlin R. Lacker ◽

Adam Pancoast ◽

Kelsey Poremba ◽

...

Keyword(s):

Cross Coupling ◽

Mild Conditions ◽

Aryl Iodides ◽

Reaction Proceeds

An asymmetric reductive cross-coupling of α-chloroesters and (hetero)aryl iodides is reported. This nickel-catalyzed reaction proceeds with a chiral BiOX ligand under mild conditions, affording α-arylesters in good yields and enantioselectivities....

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A metal-free radical cascade reaction of phosphine oxides with 2-aryloxy phenylacetylenes to assemble diphosphonyl xanthene derivatives

Organic & Biomolecular Chemistry ◽

10.1039/d1ob01045j ◽

2021 ◽

Author(s):

Tao Fan ◽

Yan Liu ◽

Caina Jiang ◽

Yanli Xu ◽

Yan-Yan Chen

Keyword(s):

Free Radical ◽

Transition Metal ◽

Cascade Reaction ◽

Phosphine Oxides ◽

Metal Free ◽

Mild Conditions ◽

Xanthene Derivatives ◽

Reaction Proceeds ◽

Radical Cascade

A radical cascade reaction of 2-aryloxy phenylacetylene with phosphine oxides promoted by K2S2O8 was developed, provided diphosphonyl xanthenes as products. This reaction proceeds under transition metal-free and mild conditions with...

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Homocoupling of terminal alkynes catalyzed by CuCl under solvent-free conditions

Journal of Chemical Research ◽

10.1177/17475198211032580 ◽

2021 ◽

pp. 174751982110325

Author(s):

Yan Xiao ◽

Jiyu Gao ◽

Peng Chen ◽

Guangliang Chen ◽

Zicheng Li ◽

...

Keyword(s):

Functional Group ◽

Reaction Times ◽

Environmentally Friendly ◽

Solvent Free ◽

Copper Salt ◽

Terminal Alkynes ◽

Mild Conditions ◽

Solvent Free Conditions ◽

Environmentally Friendly Process

A series of symmetrical 1,4-disubstituted buta-1,3-diynes is prepared with excellent yields (up to 95%) through homocoupling of terminal alkynes catalyzed by a copper salt under solvent-free conditions. This method provides an environmentally friendly process to prepare 1,3-diynes in short reaction times under mild conditions. Furthermore, the method is suitable for a wide substrate scope and has excellent functional group compatibility. The reaction can also be scaled up to gram level.

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Highly selective introduction of heteroatom groups to isocyanides and its application to electrocyclic reactions

Pure and Applied Chemistry ◽

10.1351/pac-con-12-07-01 ◽

2012 ◽

Vol 85 (4) ◽

pp. 785-799 ◽

Cited By ~ 3

Author(s):

Akiya Ogawa ◽

Taichi Tamai ◽

Takenori Mitamura ◽

Akihiro Nomoto

Keyword(s):

Cross Coupling ◽

Molecular Iodine ◽

Radical Cyclization ◽

Sharp Contrast ◽

Quinoline Derivatives ◽

Coupling Reactions ◽

Electrocyclic Reactions ◽

Cross Coupling Reactions ◽

Cyclization Process ◽

Synthetic Intermediates

Photoinduced cyclization of o-alkenylaryl isocyanides with (PhS)2 in the presence of (PhTe)2 affords the corresponding bisthiolated indene derivatives in good yields via radical cyclization process by thio radical. The procedure can be applied to the construction of tetracyclic systems by using bis(o-aminophenyl) disulfides in place of (PhS)2. In sharp contrast, when o-alkynylaryl isocyanides are employed as the substrates, novel electrocyclic reactions take place upon photoirradiation or heating at 40~80 °C to generate quinoline 2,4-biradical species, which are trapped with organic diselenides, ditellurides, and molecular iodine to give the corresponding 2,4-diseleno-, ditelluro-, and diiodo-quinoline derivatives, respectively, in good yields. The obtained quinoline derivatives are useful synthetic intermediates; for example, cross-coupling reactions using 2,4-diiodoquinolines lead to the preparation of functionalized quinoline derivatives.

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