Rh-Catalyzed Asymmetric Hydrogenation of β-Branched Enol Esters for the Synthesis of β-Chiral Primary Alcohols

Liu, Chong; Yuan, Jing; Zhang, Jian; Wang, Zhihui; Zhang, Zhenfeng; Zhang, Wanbin

doi:10.1021/acs.orglett.7b03469

Cited by 37 publications

(9 citation statements)

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“…( R )‐PhanePhos, ( R , R )‐Me‐FcPhos (the P‐Rh‐P angle of an analogous Rh I ‐complex: 99°) [51], and ( R , Sp )‐JosiPhos (the P‐Rh‐P angle of an analogous Rh I ‐complex: 95°) [52] promoted the hydrogenation with complete conversions; however unsatisfactory enantioselectivities were still observed. Similar to the trend observed for the AH of β ‐branched enol esters and β ‐branched enamides [23,33], the ligands ( R )‐SDP and ( R )‐SKP, bearing a large bite angle in their Rh I ‐complexes (97° according to the XRD of [Rh(( R )‐SKP)(cod)]SbF 6 shown in Table 1), showed high activities and enantioselectivities. To our delight, the rhodium complex of ( R )‐SKP showed the most promising results, giving the desired product with both an excellent conversion and a high enantioselectivity of 91% ee.…”

Section: Resultssupporting

confidence: 79%

“…Continuing our efforts to develop efficient AH of challenging substrates, we are conviced that the additional coordination of a directing group to the metal and attractions between the ligand and substrate play a crucial role for both high reactivity and stereoselectivity [23–41]. Typically, catalyzed by a bisphosphine‐Rh complex bearing a large bite angle (SKP [42,43] or SDP [44,45]) and assisted by a directing group (amide or ester) present in substrates, β ‐branched enamides or enol esters have been hydrogenated to produce β ‐chirogenic amines or alcohols in quantitative yields and with excellent enantioselectivities [23,33]. Inspired by these results, we wondered whether the challenging AH of γ ‐branched allylamines bearing a remote directing group, which is considered to form a larger and more unstable coordinating ring, can be realized by adopting a similar strategy.…”

Section: Resultsmentioning

confidence: 99%

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Asymmetric hydrogenation of γ‐branched allylamines for the efficient synthesis of γ‐chirogenic amines

et al. 2021

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The efficient construction of γ‐chirogenic amines has been realized via asymmetric hydrogenation of γ‐branched N‐phthaloyl allylamines by using a bisphosphine‐Rh catalyst bearing a large bite angle. The desired products possessing different γ‐substituents were obtained in quantitative yields and with excellent enantioselectivities (up to >99% ee). This protocol provides a practical method for the preparation of γ‐chirogenic amine derivatives such as the famous antidepressant drug Fluoxetine (up to 50000 S/C). The mechanistic calculations show an unusual P‐Rh‐P trans‐chelating pattern and a weak interaction‐promoted activation mode which are completely different from the traditional cis‐chelating pattern and coordination‐promoted activation mode in metal‐catalyzed hydrogenations. Key points Novel methodology of asymmetric hydrogenation was developed for efficient synthesis of γ‐chirogenic amines. New synthetic route was developed for the well‐known antidepressant drug Fluoxetine. Unusual mechanism information was found in the bidentate bisphosphine‐Rh‐catalyzed hydrogenation.

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Section: Resultssupporting

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Asymmetric hydrogenation of γ‐branched allylamines for the efficient synthesis of γ‐chirogenic amines

et al. 2021

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“…The application of SKP ligands has also been extended to the Rh-catalyzed asymmetric hydrogenation reaction of enol ester recently. As shown in Scheme 19, Rh-catalyzed asymmetric hydrogenation of β-branched enol esters 63 in the presence of SKP afforded β-chiral primary alcohol derivatives 64 with >99% conversion and excellent enantioselectivities (Scheme 19), 46 while most of the tested chiral diphosphines only gave the product 64 with low enantioselectivities (<72% ee). It should be noted that chiral ligands (S)-CH 2 OH-DPPF and (R)-PhanePhos, usually regarded as large bite angle ligands, showed dramatically improved activity in the hydrogenation of 63.…”

Section: Skp/rh(i)-catalyzed Asymmetric Alkene Hydrogenationmentioning

confidence: 99%

A Type of Structurally Adaptable Aromatic Spiroketal Based Chiral Diphosphine Ligands in Asymmetric Catalysis

et al. 2021

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Metrics & MoreArticle Recommendations CONSPECTUS: While spectacular successes have been achieved in homogeneous catalysis with the use of achiral diphosphine ligands featuring a wide natural bite angle, such as XantPhos, chiral diphosphines that can induce a large P−M−P bite angle in their transition metal complexes are conspicuously less explored in asymmetric catalysis, probably due to the challenges in the identification and efficient construction of a suitable chiral backbone. In the past decade, a highly efficient synthesis of chiral aromatic spiroketals and the corresponding diphosphine ligands (SKPs) has been developed in this group.Based on a one-pot catalytic tandem double asymmetric hydrogenation−spiroketalization ring-closure reaction sequence, these SKP ligands featuring an extraordinarily long P•••P distance and a flexible backbone have been readily prepared in large scale. Remarkably versatile coordination modes have been found in the complexes of SKP with some catalysis-relevant transition metals, for example, Pd, Cu, Au, and Rh. Whereas SKP enforces an unusually large bite angle in [Pd(SKP)Cl 2 ] and [Cu(SKP)Cl] complexes (160.1°and 132.8°, respectively), it also allows for a bimetallic Au−Au interaction (3.254 Å) in the complex of [Au 2 (SKP)Cl 2 ] or a square-planar coordination geometry for the [Rh(SKP)(cod)]SbF 6 complex. Such an adaptable nature of SKP ligands for transition metal coordination has profound consequences in homogeneous asymmetric catalysis, as demonstrated by their unique performance in several types of catalytic asymmetric reactions. One of the most exciting examples is SKP/Pd-catalyzed asymmetric allylic amination of Morita−Baylis−Hillman (MBH) adducts, in which SKP/Pd complexes demonstrated excellent control of regio-and enantioselectivities and exhibited exceptionally high efficiency (with a TON up to 4750) in the catalysis. SKP ligands have also found a diversity of successful applications in Cu-, Au-, or Rh-catalyzed asymmetric reactions, further attesting their wide utilities in asymmetric catalysis. Overall, this class of readily accessible SKP ligands featuring a chiral aromatic spiroketal skeleton have demonstrated unique adaptable structures in a variety of transition metal complexes and provided outstanding performance in some difficult asymmetric transformations. The works delineated herein would be expected to stimulate further research efforts on the application of this type of chiral ligand and to provide useful clues in the design of new chiral diphosphine ligands with adaptable bite angles for transition metal catalyzed asymmetric reactions.

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“…The hydrogenation of alkenes is an important transformation within synthetic chemistry . Advances in catalyst design have produced an array of conditions capable of chemo-, regio-, and stereoselective hydrogenation that also exhibit impressive functional-group tolerance and have led to its widespread application within industry and academia. , Conventionally, dihydrogen gas (H 2 ) is used, but many examples of the use of deuterium gas (D 2 ) have also been reported . By contrast, the use of the isotopically mixed congener hydrogen deuteride (HD) is exceptionally rare (Scheme , top). − …”

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Regioselective Transfer Hydrodeuteration of Alkenes with a Hydrogen Deuteride Surrogate Using B(C₆F₅)₃ Catalysis

Walker

Oestreich

2018

Org. Lett.

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A regioselective hydrodeuteration of alkenes using monodeuterated cyclohexa-1,4-dienes as surrogates for hydrogen deuteride (HD) gas is reported. The metal-free process proceeds under B(C 6 F 5 ) 3 catalysis presumably by deuteride abstraction to form borodeuteride [DB(C 6 F 5 ) 3 ] − and highly Brønsted-acidic Wheland intermediates. Low catalyst loadings (2.5 mol %) are used, and the reaction proceeds at room temperature.

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Rh-Catalyzed Asymmetric Hydrogenation of β-Branched Enol Esters for the Synthesis of β-Chiral Primary Alcohols

Cited by 37 publications

References 87 publications

Asymmetric hydrogenation of γ‐branched allylamines for the efficient synthesis of γ‐chirogenic amines

Asymmetric hydrogenation of γ‐branched allylamines for the efficient synthesis of γ‐chirogenic amines

A Type of Structurally Adaptable Aromatic Spiroketal Based Chiral Diphosphine Ligands in Asymmetric Catalysis

Regioselective Transfer Hydrodeuteration of Alkenes with a Hydrogen Deuteride Surrogate Using B(C₆F₅)₃ Catalysis

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Rh-Catalyzed Asymmetric Hydrogenation of β-Branched Enol Esters for the Synthesis of β-Chiral Primary Alcohols

Cited by 37 publications

References 87 publications

Asymmetric hydrogenation of γ‐branched allylamines for the efficient synthesis of γ‐chirogenic amines

Asymmetric hydrogenation of γ‐branched allylamines for the efficient synthesis of γ‐chirogenic amines

A Type of Structurally Adaptable Aromatic Spiroketal Based Chiral Diphosphine Ligands in Asymmetric Catalysis

Regioselective Transfer Hydrodeuteration of Alkenes with a Hydrogen Deuteride Surrogate Using B(C6F5)3 Catalysis

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Regioselective Transfer Hydrodeuteration of Alkenes with a Hydrogen Deuteride Surrogate Using B(C₆F₅)₃ Catalysis