New Chiral BINOL‐Based Phosphates for Enantioselective [Au(I)]‐Catalyzed Dearomatization of β‐Naphthols with Allenamides

Pedrazzani, Riccardo; An, Juzeng; Monari, Magda; Bandini, Marco

doi:10.1002/ejoc.202100166

Cited by 20 publications

(17 citation statements)

References 87 publications

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“…However, nearly all examples of Au(I)-ACDC reported to date refer to reactions of prochiral allene substrates. 3 , 4 The only exceptions are the desymmetrization of diynes described by the group of Czekelius ( Scheme 1 B) 5 and cases of tandem Au/chiral acid catalysis wherein gold is generally not involved in the enantiodetermining Brønsted acid-catalyzed step. 6 To the best of our knowledge, all other attempts to leverage chiral counterions in more challenging asymmetric Au(I)-catalyzed reactions of alkynes, 7 which, unlike allenes, cannot be prochiral in themselves, were met with failure until now.…”

Section: Introductionmentioning

confidence: 99%

“…Groundbreaking work by Toste and co-workers proved that it was possible to perform gold catalysis enantioselectively by using achiral ligands together with chiral anions, combining a dinuclear gold complex with a chiral silver phosphate to realize the asymmetric cyclization of allenes (Scheme A) . This contributed to the development of the field of “asymmetric-counteranion directed catalysis” (ACDC), and chiral anions have since been employed as stereodirecting elements in other Au(I)-catalyzed transformations, in combination with both achiral and chiral gold complexes. However, nearly all examples of Au(I)-ACDC reported to date refer to reactions of prochiral allene substrates. , The only exceptions are the desymmetrization of diynes described by the group of Czekelius (Scheme B) and cases of tandem Au/chiral acid catalysis wherein gold is generally not involved in the enantiodetermining Brønsted acid-catalyzed step .…”

Section: Introductionmentioning

confidence: 99%

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H-Bonded Counterion-Directed Enantioselective Au(I) Catalysis

2022

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A new strategy for enantioselective transition-metal catalysis is presented, wherein a H-bond donor placed on the ligand of a cationic complex allows precise positioning of the chiral counteranion responsible for asymmetric induction. The successful implementation of this paradigm is demonstrated in 5- exo -dig and 6- endo- dig cyclizations of 1,6-enynes, combining an achiral phosphinourea Au(I) chloride complex with a BINOL-derived phosphoramidate Ag(I) salt and thus allowing the first general use of chiral anions in Au(I)-catalyzed reactions of challenging alkyne substrates. Experiments with modified complexes and anions, 1 H NMR titrations, kinetic data, and studies of solvent and nonlinear effects substantiate the key H-bonding interaction at the heart of the catalytic system. This conceptually novel approach, which lies at the intersection of metal catalysis, H-bond organocatalysis, and asymmetric counterion-directed catalysis, provides a blueprint for the development of supramolecularly assembled chiral ligands for metal complexes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

H-Bonded Counterion-Directed Enantioselective Au(I) Catalysis

2022

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“…combines an iminium with a nucleophile in the presence of a chiral phosphate (Figure 3). 34 As with the chiral phosphoric acid study, to deploy the published chiral phosphate model to predict the impact of utilizing an organometallic intermediate as a reaction component, the sensitivity of the previously identified parameters to computational method must be taken into account. Because we expected natural bond orbital (NBO) charges to be sensitive to the computational methods employed, we re-optimized each iminium intermediate at the M06/def2TZVP level to ensure all electrophilic components (organic and organometallic) were treated uniformly.…”

Section: And Discussionmentioning

confidence: 99%

Transferrable Selectivity Profiles Enable Prediction in Synergistic Catalyst Space

Kuang

Reid

2021

Preprint

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Organometallic intermediates participate in many multi-catalytic enantioselective transformations directed by a chiral catalyst, but the requirement of optimizing two catalyst components is a significant barrier to widely adopting this approach for chiral molecule synthesis. Algorithms can potentially accelerate the screening process by developing quantitative structure-function relationships from large experimental datasets. However, the chemical data available in this catalyst space is limited. We report a data-driven strategy that effectively translates selectivity relationships trained on enantioselectivity outcomes derived from one catalyst reaction systems where an abundance of data exists, to synergistic catalyst space. We describe three case studies involving different modes of catalysis (Brønsted acid, chiral anion, and secondary amine) that substantiate the prospect of this approach to predict and elucidate selectivity in reactions where more than one catalyst is involved. Ultimately, the success in applying our approach to diverse areas of asymmetric catalysis implies that this general workflow should find broad use in the study and development of new enantioselective, multi-catalytic processes.

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“…This protocol has been reported to work well with 2-naphthols and 9-anthryl derived chiral phosphoric acid catalysts but there is little information on how other catalysts and nucleophiles would react. 76 Therefore, this platform provides the ideal opportunity to test our hypothesis beyond what is included in the model while allowing the reaction scope to be meaningfully extended in the process. It should be noted that this reaction can be performed solely with a Brønsted acid but the reaction requires very high molecular weight catalysts to achieve excellent levels of enantioselectivity and some substrates perform less well.…”

Section: Inverse Catalyst Designmentioning

confidence: 99%

A Statistical Modeling Approach to Catalyst Generality Assessment in Enantioselective Synthesis

Lai

Betinol

et al. 2022

Preprint

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Selecting the optimal catalyst to impart high levels of enantioselectivity in a new transformation is challenging because the ideal molecular requirements of the catalyst for one reaction do not always simply translate to another. In these reaction scenarios practitioners typically use the most general catalyst structure as a starting point for optimization. However, for many reaction systems and catalyst chemotypes the most general catalyst structure may be largely unknown presenting a significant limitation in catalyst application to new reaction space. Herein, we demonstrate that comprehensive statistical models can be applied to identify the most general catalyst for many chemical systems. These inclusive statistical models that encompass many reaction types can provide information about the relevant structural requirements necessary for high enantioselectivity across a broad reaction range. By validating this approach on diverse regions of organocatalyzed reaction space we discovered structurally distinct catalysts can in some cases provide similar levels of enantioselectivity. The second curious finding determined that the best and most popular catalyst systems may not be equivalent. Validation of this approach on a multi-catalytic dearomatization reaction resulted in the discovery that our general catalyst findings allowed for streamlined reaction development for highly complex transformations.

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New Chiral BINOL‐Based Phosphates for Enantioselective [Au(I)]‐Catalyzed Dearomatization of β‐Naphthols with Allenamides

Cited by 20 publications

References 87 publications

H-Bonded Counterion-Directed Enantioselective Au(I) Catalysis

H-Bonded Counterion-Directed Enantioselective Au(I) Catalysis

Transferrable Selectivity Profiles Enable Prediction in Synergistic Catalyst Space

A Statistical Modeling Approach to Catalyst Generality Assessment in Enantioselective Synthesis

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