Comprehensive Summary

Ureas are widely used in drugs, materials and catalysts because of their diamide structure, which can form strong hydrogen bonds. Therefore, it is of great scientific significance to develop efficient and green methods for the synthesis of urea compounds, especially unsymmetrical ureas. Here, we have disclosed novel and highly efficient three-component coupling reactions of organic halides, sodium cyanate and amines enabled by nickel/photoredox dual catalysis for the preparation of unsymmetrical ureas. The reaction features simple and safe operations, broad substrate scopes, and product diversities. It allows the facile synthesis of N-aryl/vinyl ureas from readily available, user-friendly feedstocks under mild conditions (27 examples, 36-98% yields). In addition, this method is further derived to alcohols as nucleophiles to synthesize a series of carbamates (15 examples, 40-95% yields). The mechanism experiment shows that the isocyanate produced by the coupling of halide and sodium cyanate may be the key intermediate in this reaction.

This article is protected by copyright. All rights reserved.

A one-pot synthesis of vicinal diamines using indoles, azoles and phenothiazines in a tandem multi-component reaction is developed.

Comprehensive Summary

A one-pot synthesis of vicinal diamines using indoles, azoles and phenothiazines in a tandem multi-component reaction is developed. The utilization of a copper-iodine co-catalytic system enables the generation of a diverse range of vicinal diaminoindoles with good selectivity and moderate to good yields. An attractive aspect of this method is that it can be conducted under mild and environmentally friendly conditions, showcasing its potential as an alternative approach for synthesizing vicinal diamines. Moreover, the use of a multicomponent tandem reaction highlights the power and versatility of such strategies in synthetic chemistry.

The first iron-catalyzed alkenylzincation of internal alkynes featuring mild conditions, simple operation, broad substrate scope, excellent functional group tolerance, and high activity has been developed, which provides an efficient access to multi-substituted conjugated olefins.

Comprehensive Summary

The alkenylzincation of internal alkynes is an effective method for the synthesis of multi-substituted conjugated dienes; however, the current catalytic systems for this reaction are limited in terms of substrate scope and selectivity control, which restricts its practical applications. Herein, we report the first iron-catalyzed alkenylzincation of internal alkynes, which features mild conditions, simple operation, broad substrate scope (including aryl/alkyl, diaryl, and dialkyl acetylenes), excellent functional group tolerance (tolerating highly active functional groups such as ester, methylthio, amide, sulfonyl, cyano, etc.), and high activity (with a turnover number of up to 11500, the highest record for carbometallation reactions). Notably, the catalytic system described in this article also realized the highly selective vinylzincation of unfunctionalized internal alkynes as well as the alkenylzincation of unsymmetrical diarylacetylenes and dialkyl acetylenes, which have not been achieved with other catalytic systems reported in the literatures. The current study provides a highly selective access to synthetically important multi-substituted conjugated dienes.

An efficient nickel-catalyzed cross-electrophile coupling of triazine esters with aryl bromides in the presence of magnesium powder and lithium chloride in THF is reported. The cross-coupling reactions proceeded smoothly at room temperature to afford a variety of structurally diverse diaryl ketones in moderate to good yields with wide functional group tolerance.

Comprehensive Summary

Cross-electrophile coupling of triazine esters with aryl bromides could be facilely accomplished by employing nickel as catalyst, magnesium as metal mediator, and lithium chloride as additive. The reactions proceeded efficiently in THF at room temperature through C—O bond activation to afford an array of structurally different diaryl ketones in moderate to good yields with wide functional group tolerance. Control experiments showed that nickel, magnesium, lithium chloride, and THF are all indispensable for the good performance of the coupling reaction. Preliminary mechanistic exploration indicated that in situ formed arylmagnesium reagent by the insertion of magnesium into aryl bromide might serve as the key intermediate of the cross-coupling. The method which avoids the utilization of moisture-labile and relatively difficult-to-obtain organometallics is step-economical, cost-efficient, and operationally simple, potentially serving as an attractive alternative to documented methods.

Direct alkylation with skipped enynes or cyclopropropylacetylenes represents an ideal process for the installation of pentadienyl group in terms of atom- and step-economy. We herein describe a synergistic chiral primary amine/Pd catalysis for asymmetric α-pentadienylation of β-ketocarbonyls and aldehydes with skipped enynes or cyclopropropylacetylenes. The reaction features the construction of acyclic all-carbon quaternary centers with high enantioselectivity, and good functional group tolerance and scalability.

Comprehensive Summary

Direct alkylation with skipped enynes or cyclopropropylacetylenes represents an ideal process for the installation of pentadienyl group in terms of atom- and step-economy. The development of catalytic asymmetric versions has been frequently pursued and most of the successes have been achieved with enolizable aldehydes. We herein describe a synergistic chiral primary amine/Pd catalysis for asymmetric α-pentadienylation of β-ketocarbonyls and aldehydes with skipped enynes or cyclopropropylacetylenes. The reaction features the construction of acyclic all-carbon quaternary centers with high enantioselectivity, and good functional group tolerance and scalability.

An efficient catalytic asymmetric synthesis of optically active 2,2'-dibromo-6,6'-diiodo -1,1'-biphenyl was reported. This chiral molecule features four carbon-halogen bonds, which can be sequentially elaborated to provide a variety of highly functionalized axially chiral biaryls.

Comprehensive Summary

The widespread applications of atropisomeric compounds have led to an increasing demand for their synthesis. Rather than synthesizing different functionalized atropisomers individually, an attractive alternative is to identify a key intermediate or precursor that can be readily elaborated and functionalized to realize divergent synthesis of this class of compounds. Building on our previous research on asymmetric ring-opening of cyclic diaryliodoniums, in this work we developed a copper-catalyzed enantioselective ring-opening reaction of ortho,ortho’-dibromo substituted cyclic diaryliodonium with lithium iodide. The resulting optically active product 2,2'-dibromo-6,6'-diiodo-1,1'-biphenyl, possessing two C—Br bonds and two C—I bonds, can be selectively advanced to form different functionalities. Remarkably, the utilities of the product were highlighted by successively demonstrating C—I and C—Br metalation, followed by carboxylation, boroylation, oxygenation, allylation, phosphinylation, etc., all of which provide a new and convenient approach to synthesizing a range of functionalized axially chiral biphenyls.

Comprehensive Summary

A series of 3-acyl-substituted isoindolinone derivatives were synthesized in one-pot manner via the reaction of o-bromobenzaldehydes, isocyanides, and carboxylic acids in the presence of palladium catalyst and base. The reaction employing easily available starting materials features simple operation and high efficiency. The mechanistic study showed that the reaction might undergo 1) Pd-catalyzed [3+2] cyclization of o-bromobenzaldehyde with isocyanide and the re-insertion of another molecule of isocyanide, 2) addition of carboxylic acid to in situ formed ketenimine followed by a rearrangement relay to give 3,3-diacyl-substituted isoindolinone derivative. Further transformations of the obtained products through decarbonylation could also be realized.

This article is protected by copyright. All rights reserved.

A copper-catalyzed hydrodifluoroallylation of cyclopropenes and alkenyl boronates with 3,3-difluoroallyl sulfonium salts (DFASs) has been developed. The reaction provides an array of gem-difluoroallyl cyclopropanes and borylalkanes with high efficiency and stereoselectivity under mild reaction conditions. The synthetic utility of this approach has also been demonstrated by the diversified transformations of the gem-difluoroallylated products.

Comprehensive Summary

Despite the paramount applications of organofluorine compounds in life and materials sciences, efficient strategies for stereoselectively constructing the C(sp³)-CF₂R bond at the stereogenic center remain limited. Here, we report a copper-catalyzed hydrodifluoroallylation of cyclopropenes and alkenyl boronates with 3,3-difluoroallyl sulfonium salts (DFASs). The use of DFASs overcomes the previous challenge of suppressing the reduction of fluoroalkylating reagents with M-H species. The reaction provides an array of gem-difluoroallyl cyclopropanes and borylalkanes with high efficiency and stereoselectivity under mild reaction conditions. Using chiral phosphine ligand could provide gem-difluoroallyl borylalkanes with high enantioselectivities, paving a new way for the catalytic asymmetric fluoroalkylation with ubiquitous alkenes. The advantages of this protocol are synthetic convenience, high functional group tolerance, and the synthetic versatility of the resulting gem-difluoroallyl cyclopropanes and borylalkanes. The synthetic utility of this approach has also been demonstrated by the diversified transformations of the gem-difluoroallylated products and the rapid synthesis of bioactive molecule analogs.

A homogeneous cobalt catalyst with dual hydrogenation activities was developed for deoxygenation of ketones with a Lewis acid as the co-catalyst. This protocol features a broad substrate scope and excellent functional group tolerance. Mechanistic studies supported a hydrogenation-dehydration-hydrogenation pathway for this hydrodeoxygenation reaction.

Comprehensive Summary

Reductive deoxygenation of ketones using H₂ is a highly desirable but also challenging transformation in both chemical synthesis, industrial-scale petroleum and biomass feedstock reforming processes. Herein, we report a cooperative cobalt/Lewis acid (LA)-catalyzed hydrodeoxygenation of ketones using H₂ as the reductant. In particular, the newly developed pincer cobalt catalyst possesses dual hydrogenation activities for both ketones and alkenes under the same reaction conditions. This reaction features a broad substrate scope, excellent functional-group compatibility, and potential applicability.

Abstract

Carbon monoxide (CO) has become one of the most relevant and versatile renewable C1 building blocks for chemical synthesis, especially in the fine chemicals industry, due to the development of efficient and selective catalysts for its activation. In this review, we present a comprehensive critical analysis of the last 10 years literature on the use of CO as a renewable feedstock for fine chemicals production. The review is organized by type of catalytic reaction, namely alkene and alkyne carbonylation, hydroformylation, carbonylation of aryl halides, carbonylative cross-coupling and C–H carbonylation. Notable examples of the synthesis of relevant building blocks and/or known pharmaceuticals are highlighted. Emphasis is placed on examples of utilizing CO as the C1 building block in one or more catalytic steps. The catalyst used and the reaction conditions are consistently presented throughout all of the examples.

This article is protected by copyright. All rights reserved.