Diastereoselective Iridium-Catalyzed Amination of Biosourced Isohexides Through Borrowing Hydrogen Methodology

Jacolot, Maïwenn; Moebs‐Sanchez, Sylvie; Popowycz, Florence

doi:10.1021/acs.joc.8b01162

Cited by 23 publications

(21 citation statements)

References 44 publications

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“…Herein, we disclose that by employing aN oyori Ru-diamine-diphosphine catalyst, well-known in asymmetric hydrogenation, enantiomerically enriched chiral alcohols could be produced from the cross coupling of racemic secondary alcohols with primary benzylic alcohols,providing the first examples of asymmetric Guerbet reaction. Thecatalysis disclosed also adds anew transformation to the asymmetric "borrowing hydrogen" reactions [10] reported by Nishibayashi, [7] Williams, [11] Oe, [12] Adolfsson, [8] Zhao, [13] Beller, [14] Quintard, [15] Zhou, [16] Popowycz, [17] Donohoe [9] and Dydio. [18] It proceeds via an interesting cooperative Ru-catalyzed hydrogen autotransfer and base-catalyzed isomerization process (Figure 1d).…”

Section: Introductionmentioning

confidence: 88%

Asymmetric Guerbet Reaction to Access Chiral Alcohols

et al. 2020

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The first example of an asymmetric Guerbet reaction has been developed. Using commercially available, classic Noyori RuII‐diamine‐diphosphine catalysts, well‐known in asymmetric hydrogenation, racemic secondary alcohols are shown to couple with primary alcohols in the presence of a base, affording new chiral alcohols with enantiomeric ratios of up to 99:1. Requiring no reducing agents, the protocol provides an easy, alternative route for the synthesis of chiral alcohols. Mechanistic studies reveal that the reaction proceeds via a Ru‐catalyzed asymmetric hydrogen autotransfer process in concert with a base‐promoted allylic alcohol isomerization.

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Section: Introductionmentioning

confidence: 88%

Asymmetric Guerbet Reaction to Access Chiral Alcohols

et al. 2020

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“…This step is followed by enantioselective/diastereoselective reduction of the resulting imine with the hydride. Circumventing the need for imines and reductants, and with water as the only by product, the method has since been exploited for the synthesis of a range of chiral amines by the groups of Beller, Zhou, and Popowycz (Figure ). Whilst featuring high stereoselectivity, the borrowing hydrogen strategies reported so far necessitate the use of transition‐metal catalysts, special chiral ligands, or additives, which could hamper its practical application in large‐scale pharmaceutical manufacturing.…”

Section: Introductionmentioning

confidence: 99%

Transition‐Metal‐Free Hydrogen Autotransfer: Diastereoselective N‐Alkylation of Amines with Racemic Alcohols

Xing

Xin

et al. 2019

Angew Chem Int Ed

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A practical method for the synthesis of α‐chiral amines by alkylation of amines with alcohols in the absence of any transition‐metal catalysts has been developed. Under the co‐catalysis of a ketone and NaOH, racemic secondary alcohols reacted with Ellman's chiral tert‐butanesulfinamide by a hydrogen autotransfer process to afford chiral amines with high diastereoselectivities (up to >99:1). Broad substrate scope and up to a 10 gram scale production of chiral amines were demonstrated. The method was applied to the synthesis of chiral deuterium‐labelled amines with high deuterium incorporation and optical purity, including examples of chiral deuterated drugs. The configuration of amine products is found to be determined solely by the configuration of the chiral tert‐butanesulfinamide regardless of that of alcohols, and this is corroborated by DFT calculations. Further mechanistic studies showed that the reaction is initiated by the ketone catalyst and involves a transition state similar to that proposed for the Meerwein–Ponndorf–Verley (MPV) reduction, and importantly, it is the interaction of the sodium cation of the base with both the nitrogen and oxygen atoms of the sulfinamide moiety that makes feasible, and determines the diastereoselectivity of, the reaction.

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“…With 1 mol% of catalyst 3, toluene as solvent and KOH as base at 120 °C, the amine products were obtained in yields ranging from 31% to 89% with most examples giving >95:5 dr (Figure 4-d). In 2018, Popowycz et al 26 disclosed an efficient methodology for the diastereoselective direct amination of biobased isohexides. Under the cooperative catalysis of an iridium complex (chiral or achiral) and an achiral phosphoric acid, the aminated products were obtained with good yields (44-83%) and excellent selectivity (>99:1 dr) using benzylic or aliphatic amines ( Figure 5).…”

Section: Chirality Controlled By Chiral Substratesmentioning

confidence: 99%

Synthesis of Chiral Amines via Asymmetric Hydrogen Borrowing

Wang¹,

Xing²,

Wang³

2020

Synlett

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Chiral amines have been widely used in pharmaceutical, agrochemical and fine-chemical industries. With water as the only byproduct and requiring no extra reducing reagent, the reaction of alcohols with amines via a ‘hydrogen borrowing’ pathway is a green route to prepare chiral amines. This paper gives a brief summary of progress on asymmetric amination of alcohols to produce chiral amines via the ‘hydrogen borrowing’ strategy.

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Diastereoselective Iridium-Catalyzed Amination of Biosourced Isohexides Through Borrowing Hydrogen Methodology

Cited by 23 publications

References 44 publications

Asymmetric Guerbet Reaction to Access Chiral Alcohols

Asymmetric Guerbet Reaction to Access Chiral Alcohols

Transition‐Metal‐Free Hydrogen Autotransfer: Diastereoselective N‐Alkylation of Amines with Racemic Alcohols

Synthesis of Chiral Amines via Asymmetric Hydrogen Borrowing

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