Making Spiroketal‐based Diphosphine (SKP) Ligands via a Catalytic Asymmetric Approach

Wang, Xiaoming; Ding, Kuiling

doi:10.1002/cjoc.201800247

Cited by 26 publications

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References 70 publications

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“…To this end, a highly efficient Ir-catalyzed asymmetric hydrogenation of the CC double bond of α,β-unsaturated ketones, reported by Bolm and Hou independently in 2008, appears to be ideal for rapid generation of a dihydroxyketone intermediate, wherein the carbonyl group would be flanked by two chiral carbon centers. With the inspiration of these studies, we started to develop the first catalytic asymmetric synthesis of nonracemic chiral aromatic spiroketals in 2012. , As shown in Scheme a, α,α′-bis(2-hydroxyarylidene)ketones 1 underwent double asymmetric hydrogenation of the two CC bonds smoothly using ( S , S )-Bn-SpinPHOX/Ir complex developed in this lab previously as the single chiral catalyst, and most gratifyingly, the subsequent diastereoselective spiroketalization of the corresponding dihydroxyketone intermediates proceeded spontaneously in a tandem fashion, thereby affording a series of aromatic spiroketal trans - 2 in one pot in high yields, with diastereomeric ratio up to 98/2 ( trans / cis ) and >99% ee for the trans isomer. Control experiments suggested that the iridium complexes might play a dual role in the transformation, namely, being the catalysts for both the double asymmetric hydrogenation and the ensuing spiroketalization.…”

Section: Skp Ligands: Catalytic Asymmetric Synthesis and Structural C...mentioning

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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Section: Skp Ligands: Catalytic Asymmetric Synthesis and Structural C...mentioning

confidence: 99%

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

et al. 2021

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“…α,α′-Bis(2-hydroxyarylidene) ketones were reduced with concomitant spiro ketalization (Scheme ). This is a very attractive tandem reaction that opens the door to novel spiro ketal phosphine (SKP) ligands bearing oxygens in the backbone . The reaction was catalyzed by a chiral ( S,S )-configured benzyl-substituted Ir–SpinPHOX catalyst as shown in Scheme .…”

Section: Asymmetric Catalytic Reactions With Rigid C-stereogenic Spir...mentioning

confidence: 99%

Recent Advances in Asymmetric Hydrogenation Catalysis Utilizing Spiro and Other Rigid C-Stereogenic Phosphine Ligands

2021

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Transition-metal-catalyzed asymmetric reactions have been a powerful tool in organic synthesis for many years. The design of chiral ligands with the right configuration is fundamental to induce high regio- and stereoselectivity to catalytic reactions and to achieve high turnover numbers and high yields. A challenge is the control of prochiral centers with similar electronic properties in a similar steric environment within the same molecule. Over the last 10 years, a range of novel rigid C-stereogenic chiral phosphine ligands has been developed and successfully applied in various types of asymmetric transformations. Many of these ligands are of a di-, tri-, or multidentate nature. The purpose of this Perspective is to highlight recent synthetic achievements (since 2010) with spiro-phosphines and other rigid phosphines and discuss some mechanistic aspects of the catalytic reactions.

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“…Chiral heterobicyclic molecules, such as spiroketals, spiroaminals, bicyclic acetals and their analogues, are found as the prevalent substructures occurring frequently in a number of biologically active compounds, privileged chiral ligands as well as important frameworks in functional materials . For examples, the marine natural products Xyloketal B that exhibited potential application for the treatment of Parkinson's disease and Azaspiracid‐1 was found as a new potent biotoxin (Figure ).…”

Section: Figurementioning

confidence: 99%

A Versatile Enantioselective Catalytic Cyclopropanation‐Rearrangement Approach to the Divergent Construction of Chiral Spiroaminals and Fused Bicyclic Acetals

et al. 2020

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A highly enantioselective synthesis of various chiral heterobicyclic molecules including spiroaminals and fused bicyclic acetals has been developed via a chiral copper catalyzed cyclopropanation-rearrangement (CP-RA) approach under mild reaction conditions. Remarkably, the asymmetric CP-RA for exocyclic vinyl substrates without a pro-stereogenic carbon at the b-position has been realized for the first time and a broad substrate scope with excellent results (33 examples; 34-99 % yields; > 95/5 dr and 91-99 % ee) has been achieved. An application of a successive enantioselective CP-RA approach was also described, providing a concise access to complex chiral heteropolycycles.

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Making Spiroketal‐based Diphosphine (SKP) Ligands via a Catalytic Asymmetric Approach

Cited by 26 publications

References 70 publications

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

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

Recent Advances in Asymmetric Hydrogenation Catalysis Utilizing Spiro and Other Rigid C-Stereogenic Phosphine Ligands

A Versatile Enantioselective Catalytic Cyclopropanation‐Rearrangement Approach to the Divergent Construction of Chiral Spiroaminals and Fused Bicyclic Acetals

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