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

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.

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

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.

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

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.

Practical allylation with unactivated allylic alcohols under mild conditions

2021 ◽  
Author(s):  
Shuangshuang Li ◽  
Ju Qiu ◽  
Bowen Li ◽  
Zuolian Sun ◽  
Peizhong Xie ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Catalytic System ◽  
Allylic Alcohols ◽  
Mild Conditions ◽  
Accelerate Proton

A practical palladium/calcium catalytic system was developed for dehydrative allylation concerning unactivated allylic alcohols. EtOH solvent with H2O additive was identified as powerful media to accelerate proton transfer. That catalytic...

scholarly journals Asymmetric Addition of Allylsilanes to Aldehydes – A Cr/Photoredox Dual Catalytic Approach Complementing the Hosomi–Sakurai Reaction

2021 ◽  
Author(s):  
Felix Schäfers ◽  
Subhabrata Dutta ◽  
Roman Kleinmans ◽  
Christian Mück-Lichtenfeld ◽  
Frank Glorius
Keyword(s):  
Organic Chemistry ◽  
Transition State ◽  
Bioactive Compound ◽  
General Strategy ◽  
Acid Activation ◽  
Mechanistic Studies ◽  
Mild Conditions ◽  
Homoallylic Alcohols ◽  
Synthetic Utility ◽  
Fundamental Transformation

The allylation of aldehydes is a fundamental transformation in synthetic organic chemistry. Among the multitude of available reagents, especially allylsilanes have been established as preferred allyl source. As initially reported by Hosomi & Sakurai, these non-toxic and highly stable reagents add to carbonyls via an open transition state upon Lewis acid activation. Herein, we report a general strategy to access a variety of valuable homoallylic alcohols in opposite chemo- and diastereoselectivity to the established Hosomi–Sakurai conditions by switching to photocatalytic activation in combination with a closed transition state (Chromium catalysis). Moreover, this dual catalytic approach displays a straightforward way to introduce excellent levels of enantioselectivity and its mild conditions allow for a broad substrate scope including chiral boron-substituted products as a highlight. To emphasize the synthetic utility, our method was applied as the key step in the synthesis of a bioactive compound and in the late-stage functionalization of steroid derivatives. Detailed mechanistic studies and DFT calculations hint towards an unprecedented photo-initiated chain being operative.

Isotherm, kinetics and mechanistic studies of methylene blue biosorption onto red seaweedGracilaria corticata

2015 ◽  
Vol 57 (29) ◽  
pp. 13540-13548 ◽  
Author(s):  
J. Vijayaraghavan ◽  
T. Bhagavathi Pushpa ◽  
S.J. Sardhar Basha ◽  
J. Jegan
Keyword(s):  
Methylene Blue ◽  
Mechanistic Studies

A Pd-Catalyzed in situ domino process for mild and quantitative production of 2,5-dimethylfuran directly from carbohydrates

2017 ◽  
Vol 19 (9) ◽  
pp. 2101-2106 ◽  
Author(s):  
Hu Li ◽  
Wenfeng Zhao ◽  
Anders Riisager ◽  
Shunmugavel Saravanamurugan ◽  
Zhongwei Wang ◽  
...  
Keyword(s):  
Catalytic System ◽  
Mild Conditions

A sustainable catalytic system is developed to be efficient for producing the biofuel 2,5-dimethylfuran directly from carbohydrate biomass via an in situ domino process under mild conditions.

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

2021 ◽  
Author(s):  
Feng Zhao ◽  
Sa Guo ◽  
Yan Zhang ◽  
Ting Sun ◽  
Xin Wang ◽  
...  
Keyword(s):  
Catalytic System ◽  
Mechanistic Studies ◽  
Convenient Access

We report a practical Ag-catalyzed decarboxylative difluoroalkylation–carbocyclization reaction. Various structurally diverse gem-fluorinated quinolinones were obtained in moderate to good yields. Mechanistic studies suggested that the catalytic system involved a formal...

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