A Borrowing Hydrogen Strategy for Dehydrative Coupling of Aminoisoquinolines with Benzyl Alcohols in Water

Hikawa, Hidemasa; Tan, Rie; Tazawa, Aoi; Kikkawa, Shoko; Azumaya, Isao

doi:10.1002/ejoc.201901606

Cited by 8 publications

(4 citation statements)

References 68 publications

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“…Taking the results from the control experiments and previous literature 7,8 together, we proposed a possible mechanism for the reaction (Scheme 5). First, the deprotonation of primary alcohol 3a assisted by the NaOH affords the active species A , which then participates in the reaction.…”

Section: Resultsmentioning

confidence: 99%

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Preparation of a novel cadmium-containing coordination polymer and catalytic application in the synthesis of N-alkylated aminoquinoline derivatives via the borrowing hydrogen approach

Li,

Mao,

et al. 2024

Dalton Trans.

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Section: Resultsmentioning

confidence: 99%

“…7 Later, several reports on the N -alkylation of 2-aminoquinolines were presented with homogeneous Ru, Pd catalysts. 8 However, all the above reports used noble metal catalysts for the reaction, and only one example of the substrate scope and have not conducted universal investigations of the substrate. 9…”

Section: Introductionmentioning

confidence: 99%

Preparation of a novel cadmium-containing coordination polymer and catalytic application in the synthesis of N-alkylated aminoquinoline derivatives via the borrowing hydrogen approach

Li,

Mao,

et al. 2024

Dalton Trans.

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“…Then the dehydrative condensation of benzaldehyde intermediate with amine gives the corresponding imine which is then reduced by the palladium(II) hydride complex 19 to give the target N ‐mono‐benzylated amine product and meanwhile regenerating the benzyl palladium(II) species 18 . Later, they extended this π‐benzyl palladium system‐mediated hydrogen borrowing method to the dehydrative N ‐benzylation of 2‐aminopyridines or aminoisoquinolines with benzyl alcohols in water [48,49] …”

Section: Borrowing Hydrogen Reactions In Aqueous Mediamentioning

confidence: 99%

“…Later, they extended this π-benzyl palladium system-mediated hydrogen borrowing method to the dehydrative N-benzylation of 2-aminopyridines or aminoisoquinolines with benzyl alcohols in water. [48,49] In addition to these simple water-soluble TM catalysts, some novel catalysts bearing extraordinary metal-muti-functional ligand were also reported. In 2014, Li and coworkers reported the N-alkylation of poor nucleophilic sulfonamides with alcohols in water using a muti-functional Iridium complex 20 (Scheme 31).…”

Section: Homogeneous Borrowing Hydrogen Reactionmentioning

confidence: 99%

Transition‐Metal‐Catalyzed Direct Substitution of Alcohols in Aqueous Media

Yan

2023

Eur J Org Chem

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The direct use of alcohols as the much greener and more sustainable alkylated reagents in substitution reactions is one of the emerging areas in green chemisty. However, owing to the poor leaving character of OH group, the direct substitution of alcohols is not an easy thing. Transition metal (TM) catalysis such as Pd‐catalyzed allylic/benzyl substitution and Ir‐catalyzed borrowing hydrogen provides efficient protocols for the direct substitution of alcohols, however, an organic solvent and servely anhydrous conditions are generally required. In recent decade, TM‐catalyzed direct substitution of alcohols in aqueous media was developed as a much greener alternative. In this review, the recent develpoments of this area are summarized. The activation mechanism of alcohols in aqueous reactions are emphatically discussed.

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Palladium‐Catalyzed Dehydrogenative Synthesis of Imidazoquinolines in Water

et al. 2022

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We report a synthesis of imidazoquinolines via dehydrogenative coupling of 3,4-diaminoquinolines with benzylic alcohols utilizing our π-benzylpalladium(II) system in water. Readily available benzylic alcohols initially undergo catalytic dehydrogenation to form benzaldehydes, which are then reacted with 3,4-diaminoquinolines via sequential cyclocondensation/aromatization, leading to the formation of imidazoquinolines. This experimentally simple and practical one-pot procedure provides direct access to the desired products without adding strong bases, toxic oxidants or other additives. Several experiments were carried out toward an understanding of the reaction mechanism to propose plausible catalytic cycles. The dehydrogenative coupling was found to be first order with respect to the benzyl alcohol and Pd catalyst, and zero order with respect to the 3,4-diaminoquinoline substrate. A kinetic isotope effect of 3.1 was observed by separately determining the reaction rates of benzyl alcohol and benzylα,α-d 2 alcohol. Water molecules accelerate the catalytic dehydrogenative coupling, suggesting that they act as a proton donor to activate the benzylic alcohols by a hydrogen-bonding network.

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A Borrowing Hydrogen Strategy for Dehydrative Coupling of Aminoisoquinolines with Benzyl Alcohols in Water

Cited by 8 publications

References 68 publications

Preparation of a novel cadmium-containing coordination polymer and catalytic application in the synthesis of N-alkylated aminoquinoline derivatives via the borrowing hydrogen approach

Preparation of a novel cadmium-containing coordination polymer and catalytic application in the synthesis of N-alkylated aminoquinoline derivatives via the borrowing hydrogen approach

Transition‐Metal‐Catalyzed Direct Substitution of Alcohols in Aqueous Media

Palladium‐Catalyzed Dehydrogenative Synthesis of Imidazoquinolines in Water

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