Rhodium-catalyzed alkylation of ketones and alcohols with alcohols

Yu, Xinyan; Wang, Q. Y.; Wu, Qiu‐Jin; Wang, D. W.

doi:10.1134/s107036321601028x

Cited by 25 publications

(15 citation statements)

References 17 publications

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“…In the same year, Kantam and co-workers developed a rhodium-catalyzed procedure for alkylation of ketones with primary alcohols, albeit further reduction of the ketone products was observed . Another strategy employing rhodium, this time able to obtain ketone products, was later realized by Wang and co-workers in 2016 . By this time, an increasing number of homogeneous earth-abundant transition-metal-catalyzed methods were emerging, including the works of Sortais and Darcel in 2015 and Beller and co-workers in 2016 .…”

Section: C–c Bond-forming Processesmentioning

confidence: 99%

“…26 Another strategy employing rhodium, this time able to obtain ketone products, was later realized by Wang and co-workers in 2016. 98 By this time, an increasing number of homogeneous earthabundant transition-metal-catalyzed methods were emerging, including the works of Sortais and Darcel in 2015 99 and Beller and co-workers in 2016. 100 The former demonstrated the ironcatalyzed α-alkylation of ketones with primary alcohols, including application to a Friedlander-type annulation, to synthesize quinolines from 2-aminobenzyl alcohols.…”

Section: ■ Introductionmentioning

confidence: 99%

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Borrowing Hydrogen for Organic Synthesis

et al. 2021

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Borrowing hydrogen is a process that is used to diversify the synthetic utility of commodity alcohols. A catalyst first oxidizes an alcohol by removing hydrogen to form a reactive carbonyl compound. This intermediate can undergo a diverse range of subsequent transformations before the catalyst returns the “borrowed” hydrogen to liberate the product and regenerate the catalyst. In this way, alcohols may be used as alkylating agents whereby the sole byproduct of this one-pot reaction is water. In recent decades, significant advances have been made in this area, demonstrating many effective methods to access valuable products. This outlook highlights the diversity of metal and biocatalysts that are available for this approach, as well as the various transformations that can be performed, focusing on a selection of the most significant and recent advances. By succinctly describing and conveying the versatility of borrowing hydrogen chemistry, we anticipate its uptake will increase across a wider scientific audience, expanding opportunities for further development.

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Section: C–c Bond-forming Processesmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Borrowing Hydrogen for Organic Synthesis

et al. 2021

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“…Apart from iridium‐catalyzed cross‐coupling of alcohols, [4,6] different metal‐catalyzed alkylation of alcohols was also well explored. For example, the cross‐coupling of alcohols was realized with Mn, [9] Cu, [10] Ru, [11] Ni, [12] Co, [13] Zr, [14] Rh, [15] Pd, [16] Au [17] catalysts. In addition to single metal‐catalyzed coupling, the mixed metal catalysts, such as Cu−Ag, [18] Pt−Sn, [19] Ag−Al, [20] Ru‐Ir [21] were also reported.…”

Section: Introductionmentioning

confidence: 99%

Iridium Complexes as Efficient Catalysts for Construction of α‐Substituted Ketones via Hydrogen Borrowing of Alcohols in Water

et al. 2021

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Ketones are of great importance in synthesis, biology, and pharmaceuticals. This paper reports an iridium complexes‐catalyzed cross‐coupling of alcohols via hydrogen borrowing, affording a series of α‐alkylated ketones in high yield (86 %–95 %) and chemoselectivities (>99 : 1). This methodology has the advantages of low catalyst loading (0.1 mol%) and environmentally benign water as the solvent. Studies have shown the amount of base has a great impact on chemoselectivities. Meanwhile, deuteration experiments show water plays an important role in accelerating the reduction of the unsaturated ketones intermediates. Remarkably, a gram‐scale experiment demonstrates this methodology of iridium‐catalyzed cross‐coupling of alcohols has potential application in the practical synthesis of α‐alkylated ketones.

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“…Meanwhile, considerable attention has been paid to the direct coupling of alcohols via acceptorless dehydrogenation. The cross-coupling of secondary alcohols with primary alcohols was realized with iridium, ruthenium, rhodium, copper, cobalt, and manganese catalysts. The homo-coupling of secondary alcohols to β-disubstituted ketones was also reported, but one of the β-substitutes is limited to methyl in most of the reported cases …”

Section: Introductionmentioning

confidence: 99%

Mechanism and Origin of Chemoselectivity of Ru-Catalyzed Cross-Coupling of Secondary Alcohols to β-Disubstituted Ketones

Liu

Tang

et al. 2020

J. Org. Chem.

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Ru-catalyzed cross-coupling of secondary alcohols with only byproducts H 2 and H 2 O provides a green synthetic strategy to prepare β-disubstituted ketones. Density functional theory (DFT) calculations were performed with the coupling of 1-phenylethanol and cyclohexanol as a model reaction to gain deeper mechanistic insights herein. The mechanistic details of the main reaction and the key steps of possible side reactions were clarified, and the obtained results are consistent with reported selectivity. Hydrogenation of α,β-unsaturated ketones and dehydrogenation of ruthenium hydride intermediate are direct chemoselectivity-determining stages. The hydrogenation via 1,4-addition generates more stable intermediates, being favored over that via 1,2-addition, and thus avoids the formation of alkene products. The conjugation and π−π stacking effects of phenyl and the weak electronic effect of alkyls explain the dominance of specific ketone products in the hydrogenation stage. Hydrogenation of ketone products is kinetically operative but not exergonic enough to stop the irreversible dihydrogen release in an open reaction system, and thus alcohol products are absent. Furthermore, water evaporation in aldol condensation is found to be a double-edged sword, as it can accelerate the hydrogenation stage to prevent α,β-unsaturated ketones from being the main products but decrease the selectivity therein from thermodynamics overall.

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Rhodium-catalyzed alkylation of ketones and alcohols with alcohols

Cited by 25 publications

References 17 publications

Borrowing Hydrogen for Organic Synthesis

Borrowing Hydrogen for Organic Synthesis

Iridium Complexes as Efficient Catalysts for Construction of α‐Substituted Ketones via Hydrogen Borrowing of Alcohols in Water

Mechanism and Origin of Chemoselectivity of Ru-Catalyzed Cross-Coupling of Secondary Alcohols to β-Disubstituted Ketones

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