Abstract
The ketone functional group has a unique reactivity in organic chemistry and is associated with a number of useful reactions. Catalytic methods for ketone synthesis are continually being ...developed. Here, we report a photoredox, nickel and phosphoranyl radical synergistic cross-electrophile coupling of commercially available chemicals, aromatic acids and aryl/alkyl bromides. This allows for concise synthesis of highly functionalized ketones directly, without the preparation of activated carbonyl intermediates or organometallic compounds, and thus complements the conventional Weinreb ketone synthesis. Use of the appropriate photocatalyst, ligand amount and solvents can match the reaction rate required by any simple catalytic cycle. The practicality and synthetic robustness of the reaction are illustrated by the facile synthesis of complex ketones from readily available feedstock chemicals.
The construction of an aryl ketone structural unit by means of catalytic carbon-carbon coupling reactions represents the state-of-the-art in organic chemistry. Herein we achieved the direct ...deoxygenative ketone synthesis in aqueous solution from readily available aromatic carboxylic acids and alkenes, affording structurally diverse ketones in moderate to good yields. Visible-light photoredox catalysis enables the direct deoxygenation of acids as acyl sources with triphenylphosphine and represents a distinct perspective on activation. The synthetic robustness is supported by the late-stage modification of several pharmaceutical compounds and complex molecules. This ketone synthetic strategy is further applied to the synthesis of the drug zolpidem in three steps with 50% total yield and a concise construction of cyclophane-braced 18-20 membered macrocycloketones. It represents not only the advancement for the streamlined synthesis of aromatic ketones from feedstock chemicals, but also a photoredox radical activation mode beyond the redox potential of carboxylic acids.
C-H bonds are ubiquitous in organic molecules. Homogenous gold-catalyzed direct functionalization of unsaturated C-H bonds has emerged as a powerful method in our synthetic toolbox. However, C
sp
3
...-H bonds have larger dissociation energy and lower proton acidity, and thus the efficient and exquisitely selective cleavage of this kind of chemical bonds for the formation of new carbon-carbon and carbon-heteroatom bonds is still a great challenge. In this tutorial review, we will highlight the recent achievements of gold-catalyzed oxidative and redox-neutral C
sp
3
-H bond functionalization, which opens new avenues for economical and sustainable construction of fine chemicals.
Homogeneous gold-catalyzed sp
3
C-H bond functionalization strategy opens a new avenue for economical and sustainable construction of fine chemicals.
The synthesis of all-carbon tetrasubstituted olefins under mild reaction conditions is challenging because of the inevitable issues including significant steric hindrance and the uncontrolled Z/E ...stereoselectivity. In this paper, we report the synthesis of all-carbon tetrasubstituted alkenes from readily available carboxylic acids and alkenyl triflates with the synergistic catalysis of cyclo-octa-1,5-diene(tetramethyl-1,4-benzoquinone)nickel and visible light under an air atmosphere, thus avoiding the need for a glovebox or a Schlenk line. A wide range of aromatic carboxylic acids and cyclic and acyclic alkenyl triflates undergo the C-C coupling process smoothly, forming structurally diverse alkenes stereospecifically in moderate to good yields. The practicality of the method is further illustrated by the late-stage modification of complex molecules, the one pot synthesis and gram-scale applications. This is an important step towards the valuable utilization of carboxylic acids, and it also simplifies the experimental operation of metallophotoredox catalysis with moisture sensitive nickel(0) catalysis.
Abstract
Development of catalytic amide bond-forming methods is important because they could potentially address the existing limitations of classical methods using superstoichiometric activating ...reagents. In this paper, we disclose an Umpolung amidation reaction of carboxylic acids with nitroarenes and nitroalkanes enabled by the triplet synergistic catalysis of FeI
2
, P(V)/P(III) and photoredox catalysis, which avoids the production of byproducts from stoichiometric coupling reagents. A wide range of carboxylic acids, including aliphatic, aromatic and alkenyl acids participate smoothly in such reactions, generating structurally diverse amides in good yields (86 examples, up to 97% yield). This Umpolung amidation strategy opens a method to address challenging regioselectivity issues between nucleophilic functional groups, and complements the functional group compatibility of the classical amidation protocols. The synthetic robustness of the reaction is demonstrated by late-stage modification of complex molecules and gram-scale applications.
In recent years, visible-light-mediated C–H bond functionalization has become an emerging field at the forefront of organic synthesis. It is of considerable interest to academic and industrial ...chemists owing to the atom/step economical features as well as the overall sustainability. In this Letter, we mainly discussed the recent typical examples in sp2 and sp3 C–H bond functionalization by means of visible-light photoredox catalysis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
7.
Radical deuteration Li, Nian; Li, Yantao; Wu, Xiaopeng ...
Chemical Society reviews,
08/2022, Volume:
51, Issue:
15
Journal Article
Peer reviewed
Deuterated chemicals are becoming irreplaceable in pharmaceutical engineering, material science and synthetic chemistry. Many excellent reviews have discussed acid/base-dependent or metal-catalyzed ...deuteration reactions, but radical deuterations have been discussed less. With the development of radical chemistry, there has been a rapid growth in radical deuterium-labelling technology. Diverse mild, cheap and efficient strategies for deuterium atom installation have been reported, and this review summarizes the recent achievements of radical deuteration classified by the reaction types.
This review is a systematic summary of radical deuteration with four reaction types: reductive deuteration, defunctionalization-deuteration, hydrogen-deuterium (H/D) exchange and radical deuteroalkylation.
The benzylic positions in drugs are sites that readily react with cytochrome P450 oxidases via single-electron oxidation. New synthetic methodologies to incorporate a fluoroalkyl group at the ...benzylic site are continually being developed, and in this paper, we report a metal-free and site-selective organophotoredox-catalyzed trifluoromethylthiolation of benzylic C-H bonds for a wide variety of alkyl arenes and heteroarenes. The precise and predictive regioselectivity among various C(sp
)-H bonds originates from an inner-sphere benzylic radical initiation mechanism, and avoids the use of external oxidants or hydrogen atom abstractors. Its practicality stems from the trifluoromethylthiolation of a series of drugs and complex organic molecules, which is overwhelmingly selective for benzyl groups. This operationally simple protocol can provide a general and practical access to structurally diverse benzylic trifluoromethyl sulfides produced from ubiquitous benzylic C-H bonds. Large scale trifluoromethylthiolation can be achieved with continuous flow photoredox technology.
A novel visible light promoted carbodifluoroalkylation of allylic alcohols is disclosed. A series of difluoro 1,5-dicarbonyl compounds were obtained through a tandem radical addition and 1,2-aryl ...migration process. Mechanistic analysis indicated that the 1,2-aryl rearrangement proceeded via a radical intermediate.
The first catalytic inverse hydroboration of imines with N‐heterocyclic carbene (NHC) boranes has been realized by means of cooperative organocatalysis and photocatalysis. This catalytic combination ...provides a promising platform for promoting NHC‐boryl radical chemistry under sustainable and radical‐initiator‐free conditions. The highly important functional‐group compatibility and possible application in late‐stage hydroborations represent an important step forward to an enhanced α‐amino organoboron library.
Unprecedented inversion: The first catalytic inverse hydroboration of imines with N‐heterocyclic carbene boranes has been realized by means of cooperative organocatalysis and photocatalysis. The nature of the thiol is vital for inverse hydroboration. This procedure represents an important step forward to enhancing α‐amino organoboron libraries.
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