Carbene and Photocatalyst-Catalyzed Decarboxylative Radical Coupling of Carboxylic Acids and Acyl Imidazoles to Form Ketones

2021 ◽  
Author(s):  
Shi-Chao Ren ◽  
Xing Yang ◽  
Bivas Mondal ◽  
Chengli Mou ◽  
Weiyi Tian ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Radical Coupling ◽  
Mild Conditions ◽  
Two Component ◽  
Decarboxylative Coupling ◽  
Coupling Partner ◽  
Powerful Strategy ◽  
Operational Simplicity

Abstract The carbene and photocatalyst co-catalyzed radical coupling of acyl electrophile and a radical precursor is emerging as attractive method for ketone synthesis. However, previous reports mainly limited to prefunctionalized radical precursors and two-component coupling. Herein, an N-heterocyclic carbene and photocatalyst catalyzed decarboxylative radical coupling of carboxylic acids and acyl imidazoles is disclosed, in which the carboxylic acids were directly used as radical precursors. The acyl imidazoles could also be generated in situ by reaction of a carboxylic acid with CDI thus furnishing a formally decarboxylative coupling of two carboxylic acids. In addition, the reaction was successfully extended to three-component coupling by using alkene as a third coupling partner via a radical relay process. The mild conditions, operational simplicity, and use of carboxylic acids as the reacting partners make our method a powerful strategy for construction of complex ketones from readily available starting materials, and late-stage modification of natural products and medicines.

scholarly journals Combined Photoredox and Carbene Catalysis for the Synthesis of Ketones from Carboxylic Acids

2020 ◽  
Author(s):  
Anna Davies ◽  
keegan fitzpatrick ◽  
Rick Betori ◽  
Karl Scheidt
Keyword(s):  
Carboxylic Acids ◽  
Late Stage ◽  
Pharmaceutical Compounds ◽  
Single Electron ◽  
Photoredox Catalysis ◽  
Radical Coupling ◽  
Electron Reduction

Disclosed herein is the development of a novel single-electron reduction of acyl azoliums for the formation of ketones from carboxylic acids. Facile construction of the acyl azolium <i>in situ</i> followed by a radical-radical coupling was made possible using merged NHC-photoredox catalysis. The utility of this protocol in synthesis was demonstrated in the late-stage functionalization of a variety of pharmaceutical compounds.

scholarly journals General α-Amino 1,3,4-Oxadiazole Synthesis via Late-Stage Reductive Functionalization of Tertiary Amides and Lactams

2021 ◽  
Author(s):  
Daniel Matheau-Raven ◽  
Darren J. Dixon
Keyword(s):  
Carboxylic Acid ◽  
Late Stage ◽  
Coupling Reaction ◽  
Reductive Activation ◽  
Mild Conditions ◽  
Drug Molecules ◽  
Drug Conjugates ◽  
Iminium Ion ◽  
Tertiary Amides ◽  
Coupling Partner

An iridium-catalyzed reductive three-component coupling reaction for the synthesis of medicinally relevant α-amino 1,3,4-oxadiazoles from abundant tertiary amides or lactams, carboxylic acids, and (N-isocyanimino) triphenylphosphorane, is described. Proceeding under mild conditions using (<1 mol%) Vaska’s complex (IrCl(CO)(PPh<sub>3</sub>)<sub>2</sub>) and tetramethyldisiloxane to access the key reactive iminium ion intermediates, a broad range of structurally complex α-amino 1,3,4-oxadiazole architectures were efficiently accessed from diverse carboxylic acid feedstock coupling partners. Extension to α-amino heterodiazole synthesis was readily achieved by exchanging the carboxylic acid coupling partner for C-, S-, or N-centered Brønsted acids, and provided rapid and modular access to these desirable, yet difficult-to-access, heterocycles. Furthermore, the high chemoselectivity of the catalytic reductive activation step allowed the late-stage functionalization of 10 drug molecules, including the synthesis of novel heterodiazole-fused drug-drug conjugates.<br>

Cu(II)-Catalyzed [3+2] Annulation of Thioamides with AIBN: Facile Access to Highly Functionalized Thiazolidine-4-ones

Synthesis ◽  
2021 ◽  
Author(s):  
Pragya Pali ◽  
Dhananjay Yadav ◽  
Gaurav Shukla ◽  
Maya Shankar Singh
Keyword(s):  
Double Bond ◽  
Functional Groups ◽  
Dual Role ◽  
Direct Access ◽  
One Pot ◽  
Simple Method ◽  
Two Component ◽  
Thiazolidine Ring ◽  
Coupling Partner

An efficient and versatile copper-catalyzed unprecedented intermolecular radical [3 + 2] annulation of thioamides with azobisisobutyronitrile (AIBN) is described. This two-component one-pot copper(II)-catalyzed transformation has been achieved via cascade formation of C-S/C−N bonds through the cyclization of in situ generated N,S-acetal intermediate from β-ketothioamide. This operationally simple method allows direct access to synthetically demanding thiazolidin-4-ones in good to excellent yields containing diverse functional groups of different electronic and steric nature. Remarkably, the readily available reaction partners, avoidance of expensive/toxic reagents and the gram scale synthesis are additional attributes to this strategy. AIBN here plays a dual role as radical initiator and unusual source of two carbon coupling partner. Notably, the products possess Z-stereochemistry with regard to the exocyclic C=C double bond at the 2-position of the thiazolidine ring.

scholarly journals Thio-mediated two-component coupling reaction of carboxylic acids and isonitriles under mild conditions

2009 ◽  
Vol 50 (14) ◽  
pp. 1523-1525 ◽  
Author(s):  
Xiangyang Wu ◽  
Xuechen Li ◽  
Samuel J. Danishefsky
Keyword(s):  
Carboxylic Acids ◽  
Coupling Reaction ◽  
Mild Conditions ◽  
Two Component

scholarly journals Combined Photoredox and Carbene Catalysis for the Synthesis of Ketones from Carboxylic Acids

2020 ◽  
Author(s):  
Anna Davies ◽  
keegan fitzpatrick ◽  
Rick Betori ◽  
Karl Scheidt
Keyword(s):  
Carboxylic Acids ◽  
Late Stage ◽  
Pharmaceutical Compounds ◽  
Single Electron ◽  
Photoredox Catalysis ◽  
Radical Coupling ◽  
Electron Reduction

Disclosed herein is the development of a novel single-electron reduction of acyl azoliums for the formation of ketones from carboxylic acids. Facile construction of the acyl azolium <i>in situ</i> followed by a radical-radical coupling was made possible using merged NHC-photoredox catalysis. The utility of this protocol in synthesis was demonstrated in the late-stage functionalization of a variety of pharmaceutical compounds.

scholarly journals Selective carboxylation of reactive benzylic C–H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system

2018 ◽  
Vol 14 ◽  
pp. 1087-1094 ◽  
Author(s):  
Toshifumi Dohi ◽  
Shohei Ueda ◽  
Kosuke Iwasaki ◽  
Yusuke Tsunoda ◽  
Koji Morimoto ◽  
...  
Keyword(s):  
Organic Solvent ◽  
Carboxylic Acids ◽  
Hypervalent Iodine ◽  
Homolytic Cleavage ◽  
Radical Species ◽  
Direct Introduction ◽  
Mild Conditions ◽  
High Degree ◽  
Oxidation System

An oxidation system comprising phenyliodine(III) diacetate (PIDA) and iodosobenzene with inorganic bromide, i.e., sodium bromide, in an organic solvent led to the direct introduction of carboxylic acids into benzylic C–H bonds under mild conditions. The unique radical species, generated by the homolytic cleavage of the labile I(III)–Br bond of the in situ-formed bromo-λ3-iodane, initiated benzylic carboxylation with a high degree of selectivity for the secondary benzylic position.

Highly efficient conversion of aldehydes to carboxylic acid in the presence of platinum porphyrin sensitizers, air and sunlight

2012 ◽  
Vol 16 (01) ◽  
pp. 93-100 ◽  
Author(s):  
Mahdi Hajimohammadi ◽  
Hamid Mofakham ◽  
Nasser Safari ◽  
Anahita Mortazavi Manesh
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Free Base ◽  
Aliphatic Aldehydes ◽  
Mild Conditions ◽  
Efficient Conversion ◽  
Highly Efficient ◽  
Wide Range ◽  
Platinum Porphyrin

A variety of aromatic and aliphatic aldehydes were oxidized to the corresponding carboxylic acids in the presence of platinum porphyrin, sunlight and air in acetonitrile solvent under mild conditions. Nitrobenzaldehydes were found to be very efficient 1O2 scavengers that quench the formation of acids from any aldehyde in the presence of free-base porphyrin sensitizers. However, nitrobenzaldehydes were converted to the corresponding acids in the presence of platinum porphyrins. The platinum porphyrins are very good and efficient catalysts for a wide range of applications in the aerobic conversion of aldehydes to acids.

scholarly journals Synthesis of higher carboxylic acids from ethers, CO2 and H2

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Ying Wang ◽  
Qingli Qian ◽  
Jingjing Zhang ◽  
Bernard Baffour Asare Bediako ◽  
Zhenpeng Wang ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Catalytic System ◽  
Acid Synthesis ◽  
Alternative Strategy ◽  
Mechanistic Study ◽  
Rwgs Reaction ◽  
Alkyl Iodides

AbstractSynthesis of higher carboxylic acids using CO2 and H2 is of great importance, because CO2 is an attractive renewable C1 resource and H2 is a cheap and clean reductant. Herein we report a route to produce higher carboxylic acids via reaction of ethers with CO2 and H2. We show that the reaction can be efficiently catalyzed by an IrI4 catalyst with LiI as promoter at 170 °C, 5 MPa of CO2 and 2 MPa of H2. The catalytic system applies to various ether substrates. The mechanistic study indicates that the ethers are converted to olefins, which are further transformed into alkyl iodides. The higher carboxylic acids are produced by carbonylation of alkyl iodides with CO generated in situ via RWGS reaction. This report offers an alternative strategy of higher carboxylic acid synthesis and CO2 transformation.

Silver-Promoted Regioselective Oxidative Decarboxylative C–H Alkylation of Phenanthridines with Carboxylic Acids

Synthesis ◽  
2019 ◽  
Vol 52 (02) ◽  
pp. 239-245
Author(s):  
Tianyin Huang ◽  
Yang Yu ◽  
Hui Wang ◽  
Yifan Lin ◽  
Yurui Ma ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Efficient Synthesis ◽  
One Pot ◽  
Mild Conditions ◽  
One Pot Synthesis ◽  
The Given

A novel oxidative decarboxylative C–H alkylation of phenanthridines with carboxylic acids was developed for the efficient synthesis of multi-substituted phenanthridine derivatives. The given method features easy availability of starting materials, high regioselectivity, and mild conditions. Furthermore, a one-pot synthesis of multi-substituted phenanthridine derivatives was realized by the reaction of biphenyl isocyanides and carboxylic acid.

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