Transformations of Aryl Ketones via Ligand‐Promoted C−C Bond Activation

Abstract

The coupling of aromatic electrophiles (aryl halides, aryl ethers, aryl acids, aryl nitriles etc.) with nucleophiles is a core methodology for the synthesis of aryl compounds. Transformations of aryl ketones in an analogous manner via carbon–carbon bond activation could greatly expand the toolbox for the synthesis of aryl compounds due to the abundance of aryl ketones. An exploratory study of this approach is typically based on carbon–carbon cleavage triggered by ring‐strain release and chelation assistance, and the products are also limited to a specific structural motif. Here we report a ligand‐promoted β‐carbon elimination strategy to activate the carbon–carbon bonds, which results in a range of transformations of aryl ketones, leading to useful aryl borates, and also to biaryls, aryl nitriles, and aryl alkenes. The use of a pyridine‐oxazoline ligand is crucial for this catalytic transformation. A gram‐scale borylation reaction of an aryl ketone via a simple one‐pot operation is reported. The potential utility of this strategy is also demonstrated by the late‐stage diversification of drug molecules probenecid, adapalene, and desoxyestrone, the fragrance tonalid as well as the natural product apocynin.

Recent Advances in Catalytic Conversion of 5‐Hydroxymethylfurfural (5‐HMF) to 2,5‐Dimethylfuran (2,5‐DMF): Mechanistic Insights and Optimization Strategies

“…Likewise, the oxygen atoms in the ‐OH groups of 2,5‐BHMF are activated by the CoO x species followed by hydrogenolysis producing 5‐MFA. The authors discussed the key role that 5‐MFA played as an intermediary, because it explains the formation of 5‐MTHFA as a non‐desirable product due to the hydrogenation of unsaturated bonds in furan ring and, simultaneously, explains the 2,5‐DMF formation as main product [53] . This reaction mechanism is very similar to the one that has been raised by Chen et al., showing the high capability of cobalt as a hydrogen transfer agent.…”

“…As we have discussed before the selective conversion biomass‐derived 5‐HMF into 2,5‐DMF is a promising approach for research in the field of biomass and in the heterogenous catalytic processes [1,20,53,57,69] . This way, it is possible to recognize that 5‐HMF is as crucial platform molecule for the obtainment of many interesting products which may be useful at industry level [1,46,69] .…”

“…Li et al., [53] prepared a Co 3 O 4 catalyst by co‐precipitation method and then, they were reduced at different temperatures to obtain Co‐CoO x catalytic systems which were evaluated in 5‐HMF selective hydrogenation towards 2,5‐DMF. The characterization of all catalysts was carried out by XRD, TEM, XPS, TPR‐H 2 , N 2 ‐physisorption and TPD‐NH 3 .…”

2-Methylimidazole-modulated 2D Cu metal–organic framework for 5-hydroxymethylfurfural hydrodeoxygenation

“…25 The conversion of HMF to 2,5-DMF involves not only the hydrogenation of CvO but also the cleavage of C-O. 26,27 In addition, by-products such as hydrogenation or ring opening of CvC are also produced. 28 To this end, various heterogeneous catalysts have been developed for the production of 2,5-DMF, such as the precious metals Pd, Pt, and Ru, as well as cheap transition metals like Fe, Co, Ni, and Cu.…”