Silver-Catalyzed Decarboxylative Radical Relay Difluoroalkylation-Carbocyclization: Convenient Access to CF2-Containing Quinolinones

A [3+2] Cyclization of Siloxyalkynes and Isocyanides for the Synthesis of Oxazoles

Synlett ◽

10.1055/s-0037-1610402 ◽

2018 ◽

Vol 30 (04) ◽

pp. 515-518

Author(s):

An Wu ◽

Jianwei Sun

Keyword(s):

Catalytic System ◽

Mechanistic Studies ◽

Cyclization Reactions ◽

Aromatic Heterocycles ◽

Mechanistic Insight

A mild and efficient [3+2] cyclization of siloxyalkynes for the synthesis of aromatic heterocycles is developed. It is a new addition to the cyclization reactions of these versatile species. In the presence of TBAF as promoter, siloxyalkynes react with electron-withdrawing isocyanides to form a range of oxazole products. In this reaction, siloxyalkynes contribute the C–O unit for the cyclization, which is different from previous typical examples where it is a two-carbon contributor. Mechanistic studies provided insights into the mechanism, which involves a ketene intermediate. Based on the mechanistic insight, an alternative catalytic system was also demonstrated to be effective for the same transformation.

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Rhodium-Catalyzed Oxidative Annulation of 2- or 7-Arylindoles with Alkenes/Alkynes Using Molecular Oxygen as the Sole Oxidant Enabled by Quaternary Ammonium Salt

Molecules ◽

10.3390/molecules26175329 ◽

2021 ◽

Vol 26 (17) ◽

pp. 5329

Author(s):

Weihui Zhuang ◽

Jiaqi Zhang ◽

Yanping Zheng ◽

Qiufeng Huang

Keyword(s):

Molecular Oxygen ◽

Ammonium Salt ◽

Catalytic System ◽

Quaternary Ammonium ◽

Atmospheric Pressure ◽

Quaternary Ammonium Salt ◽

Michael Reaction ◽

Mechanistic Studies ◽

Dehydrogenative Coupling

Developing an efficient catalytic system using molecular oxygen as the oxidant for rhodium-catalyzed cross-dehydrogenative coupling remains highly desirable. Herein, rhodium-catalyzed oxidative annulation of 2- or 7-phenyl-1H-indoles with alkenes or alkynes to assemble valuable 6H-isoindolo[2,1-a]indoles, pyrrolo[3,2,1-de]phenanthridines, or indolo[2,1-a]isoquinolines using the atmospheric pressure of air as the sole oxidant enabled by quaternary ammonium salt has been accomplished. Mechanistic studies provided evidence for the fast intramolecular aza-Michael reaction and aerobic reoxidation of Rh(I)/Rh(III), facilitated by the addition of quaternary ammonium salt.

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Synthesis of 1,5-Functionalized 1,2,3-Triazoles Using Ionic Liquid/Iron(III) Chloride as Efficient and Reusable Homogeneous Catalyst

10.20944/preprints201807.0620.v1 ◽

2018 ◽

Author(s):

Antonio De Nino ◽

Pedro Merino ◽

Vincenzo Algieri ◽

Monica Nardi ◽

Maria Luisa Di Gioia ◽

...

Keyword(s):

Ionic Liquid ◽

Liquid Iron ◽

Catalytic System ◽

Dipolar Cycloaddition ◽

Homogeneous Catalyst ◽

Mechanistic Studies ◽

Elimination Process ◽

Cheap Method

An efficient, eco-compatible and very cheap method for the construction of triazoles via eliminative azide–olefin cycloaddition (EAOC) reaction has been developed by a catalytic system IL/FeCl3, offering an highly regioselective approach to structurally diverse 1,5-disubstituted 1,2,3-triazoles in up to 95% yield. This strategy features the reuse of catalytic system through simple operations. Mechanistic studies indicated that an asynchronous concerted dipolar cycloaddition-elimination process might be involved.

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First experimental evidence for a bis-ethene chromium(I) complex forming from an activated ethene oligomerization catalyst

Science Advances ◽

10.1126/sciadv.abd7057 ◽

2020 ◽

Vol 6 (51) ◽

pp. eabd7057

Author(s):

S. Chabbra ◽

D. M. Smith ◽

N. L. Bell ◽

A. J. B. Watson ◽

M. Bühl ◽

...

Keyword(s):

Electron Paramagnetic Resonance ◽

Experimental Evidence ◽

Catalytic System ◽

Isotope Labeling ◽

Catalytic Transformation ◽

Mechanistic Studies ◽

Paramagnetic Resonance ◽

Electron Paramagnetic

A bis-ethene chromium(I) species, which is the postulated key intermediate in the widely accepted metallacyclic mechanism for ethene oligomerization, is experimentally observed. This catalytic transformation is an important commercial route to linear α-olefins (primarily, 1-hexene and 1-octene), which act as comonomers for the production of polyethene. Here, electron paramagnetic resonance studies of a catalytic system based on [Cr(CO)4(PNP)][Al(OC(CF3)3)4] [PNP = Ph2PN(iPr)PPh2] activated with Et6Al2 provide the first unequivocal evidence for a chromium(I) bis-ethene complex. The concentration of this species is enhanced under ethene and isotope labeling studies that confirm its composition as containing [Cr(C2H4)2(CO)2(PNP)]+. These observations open a new route to mechanistic studies of selective ethene oligomerization.

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Development of highly efficient platinum catalysts for hydroalkoxylation and hydroamination of unactivated alkenes

Nature Communications ◽

10.1038/s41467-021-22287-w ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yali Zhou ◽

Xingjun Xu ◽

Hongwei Sun ◽

Guanyu Tao ◽

Xiao-Yong Chang ◽

...

Keyword(s):

Catalytic System ◽

Rational Design ◽

Platinum Catalysts ◽

High Reactivity ◽

Structural Components ◽

Mechanistic Studies ◽

Mild Conditions ◽

Naturally Occurring ◽

Donor Acceptor ◽

Type Intermediate

AbstractHydrofunctionalization, the direct addition of an X–H (e.g., X=O, N) bond across an alkene, is a desirable strategy to make heterocycles that are important structural components of naturally occurring molecules. Described here is the design and discovery of “donor–acceptor”-type platinum catalysts that are highly effective in both hydroalkoxylation and hydroamination of unactivated alkenes over a broad range of substrates under mild conditions. A number of alkene substitution patterns are accommodated, including tri-substituted, 1,1-disubstituted, (E)-disubstituted, (Z)-disubstituted and even mono-substituted double bonds. Detailed mechanistic investigations suggest a plausible pathway that includes an unexpected dissociation/re-association of the electron-deficient ligand to form an alkene-bound “donor–acceptor”-type intermediate. These mechanistic studies help understand the origins of the high reactivity exhibited by the catalytic system, and provide a foundation for the rational design of chiral catalysts towards asymmetric hydrofunctionalization reactions.

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Micellar photocatalysis enables divergent C-H arylation and N dealkylation of benzamides via N-acyliminium cations

10.33774/chemrxiv-2021-fm09s-v2 ◽

2022 ◽

Author(s):

Martyna Cybularczyk-Cecotka ◽

Jędrzej Predygier ◽

Stefano Crespi ◽

Joanna Szczepanik ◽

Maciej Giedyk

Keyword(s):

Methylene Blue ◽

Light Source ◽

Catalytic System ◽

Chemical Space ◽

Mechanistic Studies ◽

Mild Conditions ◽

Reducing Conditions ◽

Benzamide Derivatives

Micellar photocatalysis has recently opened new avenues to activate strong carbon halide bonds. So far, however, it has mainly explored strongly reducing conditions restricting the available chemical space to radical or anionic reactivity. Here, we demonstrate a radical-polar crossover process involving cationic intermediates, which enables chemodivergent modification of chlorinated benzamide derivatives via either C H arylation or N dealkylation. The catalytic system operates under mild conditions employing methylene blue as a photocatalyst and blue LEDs as the light source. Factors determining the reactivity of substrates and preliminary mechanistic studies are presented.

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A Widely Applicable Dual Catalytic System for Cross-Electrophile Coupling Enabled by Mechanistic Studies

ACS Catalysis ◽

10.1021/acscatal.0c03237 ◽

2020 ◽

Vol 10 (21) ◽

pp. 12642-12656

Author(s):

David J. Charboneau ◽

Emily L. Barth ◽

Nilay Hazari ◽

Mycah R. Uehling ◽

Susan L. Zultanski

Keyword(s):

Catalytic System ◽

Mechanistic Studies

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Development of Highly Efficient Platinum Catalysts for Hydroalkoxylation and Hydroamination of Unactivated Alkene

10.21203/rs.3.rs-82534/v1 ◽

2020 ◽

Author(s):

Yali Zhou ◽

Xingjun Xu ◽

Hongwei Sun ◽

Guanyu Tao ◽

Xiaoyong Chang ◽

...

Keyword(s):

Catalytic System ◽

Rational Design ◽

Platinum Catalysts ◽

High Reactivity ◽

Structural Components ◽

Mechanistic Studies ◽

Mild Conditions ◽

Naturally Occurring ◽

Donor Acceptor ◽

Type Intermediate

Abstract Hydrofunctionalization, the direct additon of an X–H (e.g., X = O, N) bond across an alkene, is a desirable strategy to make heterocycles that are important structural components of naturally occurring molecules. Described here is the design and discovery of “donor–acceptor”-type platinum catalysts that are highly effective in both hydroalkoxylation and hydroamination of unactivated alkenes over a broad range of substrates under mild conditions. A number of alkene substitution patterns were accommodated, including tri-substituted, 1,1-disubstituted, (E)-disubstituted, (Z)-disubstituted and even mono-substituted double bonds. Detailed mechanistic investigations suggest a plausible pathway that includes an unexpected dissociation/re-association of the electron-deficient ligand to form an alkene-bound “donor–acceptor”-type intermediate. These mechanistic studies help understand the origins of the high reactivity exhibited by the catalytic system, and provide a foundation for the rational design of chiral catalysts towards asymmetric hydrofunctionalization reactions.

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Organoselenium and DMAP co-catalysis: regioselective synthesis of medium-sized halolactones and bromooxepanes from unactivated alkenes

Chemical Communications ◽

10.1039/c5cc10245f ◽

2016 ◽

Vol 52 (22) ◽

pp. 4179-4182 ◽

Cited By ~ 34

Author(s):

Ajay Verma ◽

Sadhan Jana ◽

Ch. Durga Prasad ◽

Abhimanyu Yadav ◽

Sangit Kumar

Keyword(s):

Catalytic System ◽

Regioselective Synthesis ◽

Mechanistic Studies

A co-catalytic system has been developed for the synthesis of medium-sized halolactones and bromooxepanes possessing high transannular strain. Mechanistic studies reveal that quaternary selenium intermediate is involved in catalysis.

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