Manganese-Catalyzed β-Alkylation of Secondary Alcohols with Primary Alcohols under Phosphine-Free Conditions

Liu, Tingting; Wang, Liandi; Wu, Kaikai; Yu, Zhengkun

doi:10.1021/acscatal.8b01960

Cited by 160 publications

(57 citation statements)

References 58 publications

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“…They have utilized 0.1 mol % catalytic loading for their reaction and hence our catalysts Ru1 – Ru2 were found to be more effective compared to the catalysts reported by Kundu and co‐workers . However, our catalysts were observed to be less effective than Ru‐NHC based catalyst (0.0001 mol %) reported by the above group …”

Section: Resultsmentioning

confidence: 47%

Efficient Organoruthenium Catalysts for α‐Alkylation of Ketones and Amide with Alcohols: Synthesis of Quinolines via Hydrogen Borrowing Strategy and their Mechanistic Studies

Maji

Singh

et al. 2020

ChemCatChem

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A new family of phosphine free organometallic ruthenium(II) catalysts (Ru1–Ru4) supported by bidentate NN Schiff base ligands (L1–L4 where L1=N,N‐dimethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐ylmethyl)hydrazineylidene)methyl) aniline, L2=N,N‐diethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐ylmethyl)hydrazineylidene)methyl)aniline, L3=N,N‐dimethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐yl)hydrazineylidene)methyl)‐ aniline and L4=N,N‐diethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐yl)hydrazineylidene)methyl) aniline) was prepared and characterized. These half‐sandwich complexes acted as catalysts for C−C bond formation and exhibited excellent performance in the dehydrogenative coupling of ketones and amides. In the synthesis of C–C bonds, alcohols were utilized as the alkylating agent. A broad range of substrates, including sterically hindered ketones and alcohols, were well tolerated under the optimized conditions (TON up to 47000 and TOF up to 11750 h−1). This ruthenium (II) catalysts were also active towards the dehydrogenative cyclization of o‐amino benzyl alcohol for the formation of quinolines derivatives. Various polysubstituted quinolines were synthesized in moderate to excellent yields (TON up to 71000 and TOF up to 11830 h−1). Control experiments were carried out and the ruthenium hydride intermediate was characterized to support the reaction mechanism and a probable reaction pathway of dehydrogenative coupling for the C−C bond formation has been proposed.

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Section: Resultsmentioning

confidence: 47%

Efficient Organoruthenium Catalysts for α‐Alkylation of Ketones and Amide with Alcohols: Synthesis of Quinolines via Hydrogen Borrowing Strategy and their Mechanistic Studies

Maji

Singh

et al. 2020

ChemCatChem

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“…The major challenge is that the alkylation of secondary alcohols with primary alcohols often leads to mixtures of the β‐alkylated alcohols and the β‐alkylated ketones, presenting a tricky selectivity issue (Scheme ) . Very recently, Kempe, Rueping, Yu, and co‐workers reported the β‐alkylation of secondary alcohols with primary alcohols to provide β‐alkylated alcohols using Mn complexes (Scheme b). On the other hand, the β‐alkylation of secondary alcohols with methanol to provide β‐methylated alcohols using Mn complexes were also reported by Leitner, Kempe, and co‐workers .…”

Section: Methodsmentioning

confidence: 99%

Sustainable and Selective Alkylation of Deactivated Secondary Alcohols to Ketones by Non‐bifunctional Pincer N‐heterocyclic Carbene Manganese

Lan

Huang

et al. 2020

ChemSusChem

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A sustainable and green route to access diverse functionalized ketones via dehydrogenative–dehydrative cross‐coupling of primary and secondary alcohols is demonstrated. This borrowing hydrogen approach employing a pincer N‐heterocyclic carbene Mn complex displays high activity and selectivity. A variety of primary and secondary alcohols are well tolerant and result in satisfactory isolated yields. Mechanistic studies suggest that this reaction proceeds via a direct outer‐sphere mechanism and the dehydrogenation of the secondary alcohol substrates plays a vital role in the rate‐limiting step.

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“…However, at the outset of this work, the alkylation of secondary alcohols using/from primary alcohols by Mn catalysis was not known to the best of our knowledge. During the preparation of this Communication a related parallel study was reported by Yu and co‐workers . Here, we demonstrate that the Mn–PNN pincer complex Mn‐1 is a remarkably active and selective catalyst for the alkylation reaction of alcohols (Scheme )…”

Section: Methodsmentioning

confidence: 99%

C‐Alkylation of Secondary Alcohols by Primary Alcohols through Manganese‐Catalyzed Double Hydrogen Autotransfer

et al. 2018

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A new Mn‐catalyzed alkylation of secondary alcohols with non‐activated alcohols is presented. The use of a stable and well‐defined manganese pincer complex, stabilized by a PNN ligand, together with a catalytic amount of base enabled the conversion of renewable alcohol feedstocks to a broad range of higher‐value alcohols in good yields with water as the sole byproduct. The strategy eliminates the need for exogenous and detrimental alkyl halides as well as the use of noble metal catalysts, making the C‐alkylation through double hydrogen autotransfer a highly sustainable and environmentally benign process. Mechanistic investigations support a hydrogen autotransfer mechanism in which a non‐innocent ligand plays a crucial role.

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Manganese-Catalyzed β-Alkylation of Secondary Alcohols with Primary Alcohols under Phosphine-Free Conditions

Cited by 160 publications

References 58 publications

Efficient Organoruthenium Catalysts for α‐Alkylation of Ketones and Amide with Alcohols: Synthesis of Quinolines via Hydrogen Borrowing Strategy and their Mechanistic Studies

Efficient Organoruthenium Catalysts for α‐Alkylation of Ketones and Amide with Alcohols: Synthesis of Quinolines via Hydrogen Borrowing Strategy and their Mechanistic Studies

Sustainable and Selective Alkylation of Deactivated Secondary Alcohols to Ketones by Non‐bifunctional Pincer N‐heterocyclic Carbene Manganese

C‐Alkylation of Secondary Alcohols by Primary Alcohols through Manganese‐Catalyzed Double Hydrogen Autotransfer

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