Chiral Bicyclic NHC/Cu Complexes for Catalytic Asymmetric Borylation of α,β-Unsaturated Esters

Miwa, Yuya; Kamimura, Takumi; Sato, K.; Shishido, Daichi; Yoshida, Kazuhiro

doi:10.1021/acs.joc.9b02096

Cited by 12 publications

(5 citation statements)

References 40 publications

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“…Recently, our group has developed optically active bicyclic NHC ligands 3 having a rigid and effective chiral environment (Scheme ). An important feature of our ligands is their modularity; that is, a variety of 3 can be prepared by combining various enantiomerically pure imidazoles 1 and electrophiles (R′-X). In fact, by taking advantage of this feature, we have found catalytic systems that exhibit good enantioselectivities in the Ir-catalyzed asymmetric transfer hydrogenation of ketones (up to 98% ee) and the Cu-catalyzed asymmetric borylation reaction of α,β-unsaturated esters (up to 85% ee).…”

Section: Introductionmentioning

confidence: 87%

“…THF was distilled from sodium benzophenone ketyl under argon prior to use. Imidazolium salts 2 , dimesityliodonium trifluoromethanesulfonate, [RhCl(cod)] 2 , and oxabenzonorbornadienes 6 were prepared according to the reported procedures. Cu(OAc) 2 ·H 2 O, anhydrous DMF, Amberlite IRA402 chloride form, Ag 2 O, NaI, NaBr, KI, CsI, TBAI, N -methylaniline, N -ethylaniline, 3-methyl- N -methylaniline, and 3-chloro- N -methylaniline were used as received.…”

Section: Methodsmentioning

confidence: 99%

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Chiral Bicyclic NHC/Rh Complexes and Their Application to Catalytic Asymmetric Ring-Opening Reaction of Oxabenzonorbornadienes with Amines

Seki

Yoshida

2022

J. Org. Chem.

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A rhodium complex bearing a chiral bicyclic NHC ligand, [RhCl(3az)(cod)] 4az, was synthesized and fully characterized by X-ray diffraction analysis, high-resolution mass spectrometry, and multinuclear NMR spectroscopy. The electronic and steric properties of NHC ligand 3az were evaluated by IR measurement and X-ray diffraction analysis of dicarbonyl complex [RhCl(3az)(CO) 2 ] 5az, which was prepared by replacing the COD ligand of 4az with CO. The potential of novel complex 4az as a chiral catalyst was investigated in the Rh-catalyzed asymmetric ringopening reaction of oxabenzonorbornadienes with amines, and the corresponding products were afforded in good yields with good enantioselectivities (up to 81% ee).

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Section: Introductionmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 99%

Chiral Bicyclic NHC/Rh Complexes and Their Application to Catalytic Asymmetric Ring-Opening Reaction of Oxabenzonorbornadienes with Amines

Seki

Yoshida

2022

J. Org. Chem.

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“…As a complement to this approach, we recently reported a 'configuration sampling' strategy demonstrating that the position of the pendant group on the five-membered heterocycle is of utmost importance in achieving high enantioselectivity in a conjugate boron addition reaction (Scheme 1b). 20 A variety of different ligand types such as bisphosphines (Josiphos, 21,22 Qui-noxP*, 23 Taniaphos), 24 NHCs, 25,26 and other planar chiral ligands 27,28 are effective here, but other P,N-ligands have been met with limited success. Our interest in this reaction is primarily to push the boundaries of the P,N-ligand class with our ligand design.…”

Section: Feature Synthesismentioning

confidence: 99%

Tuning StackPhim Ligands: Applications in Enantioselective Borylation and Alkynylation

2022

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In this manuscript we present a new Stack-Ligand with a modified imidazoline backbone prepared from cyclohexane diamine. This new Stack-Ligand, Cy-StackPhim, has been found to complement the parent StackPhim ligand in an enantioselective borylation reaction. Additionally, a correlation between the nature of substituents on the imidazoline ring and the substituents on the electrophile is also discussed.

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“…Compared to simple olefins, a, β -unsaturated compounds are more reactive and could be used as substrates to selectively form C-B bonds at the β -position, so methods [ 18 , 19 , 20 , 21 , 22 , 23 ] to achieve conjugated boron addition reactions via a, β -unsaturated compounds have been developed successively. Transition metals such as rhodium [ 24 , 25 ], palladium [ 26 , 27 ], platinum [ 28 , 29 ], nickel [ 30 , 31 ] and copper [ 32 , 33 ] are mostly used as catalysts. The use of copper salts or copper complexes as catalysts will greatly reduce the cost of the reaction and therefore have an important place in the conjugation borylation of α, β -unsaturated compounds.…”

Section: Introductionmentioning

confidence: 99%

Copper Foam as Active Catalysts for the Borylation of α, β-Unsaturated Compounds

Zheng

Liu

Meng

et al. 2022

IJMS

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The use of simple, inexpensive, and efficient methods to construct carbon–boron and carbon–oxygen bonds has been a hot research topic in organic synthesis. We demonstrated that the desired β-boronic acid products can be obtained under mild conditions using copper foam as an efficient heterogeneous catalyst. The structure of copper foam before and after the reaction was investigated by polarized light microscopy (PM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and the results have shown that the structure of the catalyst copper foam remained unchanged before and after the reaction. The XPS test results showed that the Cu(0) content increased after the reaction, indicating that copper may be involved in the boron addition reaction. The specific optimization conditions were as follows: CH3COCH3 and H2O were used as mixed solvents, 4-methoxychalcone was used as the raw material, 8 mg of catalyst was used and the reaction was carried out at room temperature and under air for 10 h. The yield of the product obtained was up to 92%, and the catalytic efficiency of the catalytic material remained largely unchanged after five cycles of use.

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Chiral Bicyclic NHC/Cu Complexes for Catalytic Asymmetric Borylation of α,β-Unsaturated Esters

Cited by 12 publications

References 40 publications

Chiral Bicyclic NHC/Rh Complexes and Their Application to Catalytic Asymmetric Ring-Opening Reaction of Oxabenzonorbornadienes with Amines

Chiral Bicyclic NHC/Rh Complexes and Their Application to Catalytic Asymmetric Ring-Opening Reaction of Oxabenzonorbornadienes with Amines

Tuning StackPhim Ligands: Applications in Enantioselective Borylation and Alkynylation

Copper Foam as Active Catalysts for the Borylation of α, β-Unsaturated Compounds

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