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Amides are ubiquitous in biological and medicinal chemistry. In their Research Article (e202112668), Jiannan Zhao and co-workers report an “oxidation–reduction condensation” reaction through the use of PPh₃ as an organic reductant. Synergistic cooperation between a Co(III) and an Ir(III) photoredox catalyst captures electrons from phosphorus and facilitates the formation of acyloxyphosphonium species, which enable direct amidation. The synthetic utility of this photocatalytic method is highlighted by rapid gram-scale peptide synthesis and successful assembly of a tetrapeptide through SPPS.

Photocatalytic hydrogen atom transfer (HAT) transfer is applied to the stereoselective addition of alkanes, acetales, ethers, formamide and aldehydes to levoglucosenone. Bond dissociation energies and partial charges have been calculated in order to discuss the highly selective HAT at cyrene^TM.

Abstract

Using photocatalysis with tetra-n-butylammonium decatungstate (TBADT), alkanes, cyclic acetals, cyclic ethers, formamide and aldehydes were added in a stereoselective way to levoglucosenone (LGO). A hydrogen atom is transferred from the donor compound to the photochemically excited TBADT, and the resulting radicals add onto LGO in a stereoselective way. In the case of the addition of adamantane, two regio-isomers were obtained which form a crystalline solid solution. Cyrene™, obtained by hydrogenation of LGO, was added under the same conditions. In this case, only two of 32 possible isomers of the resulting Cyrene™ dimer were formed. The regio-selectivity of the HAT step is discussed in detail. For this purpose, bond dissociation energies and partial charges have been calculated. Transition state calculations of the radical addition to LGO explain the stereospecificity of this reaction step.

Synthesis
DOI: 10.1055/a-1678-8528

In recent decades, organic isocyanates and isothiocyanates have been often applied as reactive intermediates in research syntheses or manufacturing routes of many agrochemicals. These heterocumulenes allowed the installation of crucial carboxylic functions, such as carbamates, ureas, and semicarbazones, but have also been used for the construction of five- and six-membered heterocycles, such as tetrazolones, thiazoles, and uracils.1 Introduction2 Preparation of Carboxylic Acid Functions3 Preparation of Heterocyclic Rings4 Conclusion
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Article in Thieme eJournals:
Table of contents  |  Abstract  |  Full text

Nature Communications, Published online: 29 November 2021; doi:10.1038/s41467-021-27165-z

Phenolic compounds are important functionalities in synthetic, natural, and industrial chemistry. Recently, the photochemical activity of their corresponding electron-rich anions (phenolates) has been exploited to perform novel carbon-carbon bond-forming reactions. This Minireview article describes the main features of excited state phenolates, highlighting their ability to drive radical organic transformations. We foresee that this Minireview might stimulate forthcoming investigations in such research field. For more information see the Minireview by Filippini, Prato et al. on page 16062.

Synthesis
DOI: 10.1055/a-1647-7292

The modular synthesis of carbazole functionalized phthalimides (PIs) and their applicability as catalyst in selected photocatalytic transformations are reported. The developed synthetic approach provides high variability of phthalimide considering that the synthesis of the phthalimide core can be easily performed. Starting from fluorophthalic acid anhydrides, the corresponding fluorophthalimides were prepared with various amines, and the fluoro function ensured the introduction of carbazoles into the phthalimide framework through aromatic nucleophilic substitution. Besides the synthetic developments, some of the carbazolyl phthalimides were tested in four different photocatalytic transformations, which showed attractive and comparable activity to the known 4-CzIPN and noble metal complexes.
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Article in Thieme eJournals:
Table of contents  |  Abstract  |  Full text

A dual Cu/Ni catalytic system is identified for linear selective hydroalkylation of vinylarenes with complementary regioselectivities to similar catalytic systems. Turnover numbers (TONs) with respect to Ni are as high as 72, and Cu is revealed to accelerate the rate of formation of the linear alkyl nickel intermediate. Examples for the diversification of pharmaceuticals are also demonstrated.

Abstract

Disclosed here is a dual copper and nickel catalytic system with a silyl hydride source for promoting the linear selective hydroalkylation of vinylarenes. This carbon–carbon bond-forming protocol is applied to couple a variety of functionalized vinylarenes with alkyl halides applying a nickel(II) NNN pincer complex in the presence of an NHC-ligated copper catalyst. This combination allows for a 1 mol % loading of the nickel catalyst leading to turnover numbers of up to 72. Over 40 examples are presented, including applications for pharmaceutical diversification. Labeling experiments demonstrated the regioselectivity of the reaction and revealed that the copper catalyst plays a crucial role in enhancing the rate for formation of the reactive linear alkyl nickel complex. Overall, the presented work provides a complimentary approach for hydroalkylation reactions, whilst providing a preliminary mechanistic understanding of the cooperativity between the copper and nickel complexes.

Nature, Published online: 29 October 2021; doi:10.1038/d41586-021-02961-1

The Front Cover shows highly versatile reagents gravitating in the galaxy of reactions aiming to introduce fluorine-containing units, namely fluoroalkylchalcogenosulfonates. Indeed, this family of compounds enables trifluoromethylation, trifluoromethylsulfonylation, fluoroalkylthiolation, and fluoroalkylselenolation reactions through several activation modes. Thus, these valuable fluorinated motifs can be introduced following electrophilic, nucleophilic, or radical pathways onto a plethora of organic substrates. More information can be found in the Minireview by C. Ghiazza and T. Billard.

Various symmetrical aryl thiosulfonates are efficiently synthesized via reductive coupling of aryl sulfonyl chlorides in the presence of copper catalyst and organic amine reductant. This simple and convenient protocol also shows good functional group tolerance and features a broad substrate scope.

Abstract

A variety of symmetrical thiosulfonates are synthesized via Cu-catalyzed reductive homocoupling of aryl sulfonyl chlorides. This protocol uses organic amine acting as a mild reductant and low-cost copper as an effective catalyst. Such a reductive coupling process features a broad substrate scope and good functional group tolerance. Related thiosulfonate products can also be converted into diverse functional molecules.