Design and Synthesis of Oxazoline-Based Scaffolds for Hybrid Lewis Acid/Lewis Base Catalysis of Carbon–Carbon Bond Formation

Wiedenhoeft, Dennis; Benoit, Adam R.; Porter, Jacob D.; Wu, Yibiao; Virdi, Rajdeep S; Shanaa, Alaa; Dockendorff, Chris

doi:10.1055/s-0035-1560436

Synthesis

2016

DOI: 10.1055/s-0035-1560436

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Design and Synthesis of Oxazoline-Based Scaffolds for Hybrid Lewis Acid/Lewis Base Catalysis of Carbon–Carbon Bond Formation

Dennis Wiedenhoeft

Adam R. Benoit

Jacob D. Porter

et al.

Abstract: A new class of hybrid Lewis acid/Lewis base catalysts has been designed and prepared with an initial objective of promoting stereoselective direct aldol reactions. Several scaffolds were synthesized that contain amine moieties capable of enamine catalysis, connected to heterocyclic metalchelating sections composed of an oxazole-oxazoline or thiazole-oxazoline. Early screening results have identified oxazole-oxazoline-based systems capable of promoting a highly diastereo-and enantioselective direct aldol reacti… Show more

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Cited by 4 publications

References 28 publications

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The Use of Lewis Acids for Repairing Chemoselectivity of the Organocatalyzed Morita‐Baylis‐Hillman Reaction

Fallek

Portnoy

2019

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A substantial improvement in the chemoselectivity of the Morita-Baylis-Hillman reaction was realized by adding a diimino-or diaminopyridine coordination site within the backbone of bis-imidazole organocatalysts and using Lewis acids situated at this coordination site. The optimal outcome of 90-95% selectivity was achieved by proper matching of the catalyst/additive pair, as well as their respective amount (0.4 equiv. of AgOAc per 1 equiv. of diaminopyridine-incorporating catalyst).

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The Use of Lewis Acids for Repairing Chemoselectivity of the Organocatalyzed Morita‐Baylis‐Hillman Reaction

Fallek

Portnoy

2019

ChemistrySelect

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Computationally‐Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

2020

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Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehydes/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that pyridine‐2,6‐bis(oxazoline) (PyBOX)‐Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan's imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C−C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. Consistent with the calculations, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (t‐Bu)PyBOX‐Pt2+ complex. The desired intermolecular C−C bond formation was not observed under several different conditions, but this novel catalytic system facilitated an intramolecular C−C bond formation (Conia‐ene type reaction) with a formyl alkyne substrate.

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DFT-assisted design and evaluation of bifunctional copper(I) catalysts for the direct intermolecular addition of aldehydes and ketones to alkynes

et al. 2018

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Bifunctional catalysts containing discrete metal pi-acid and amine sites were designed and investigated for the direct intermolecular addition of aldehydes and ketones to unactivated alkynes. Copper(I)-based catalystswere prioritized based on intramolecular (Conia-ene type) reactions, and complexes were designed with tridentate ligands and potentially hemilabile heterocyclic spacers. The structures of the designed catalysts were computed using density functional theory (DFT), and the relative energies of putative catalytic intermediates were estimated and used to prioritize catalyst designs. Novel bifunctional precatalysts containing a thiazole spacer were synthesized via a 9-step sequence and combined with transition metals before screening for the direct addition of aldehydes and ketones to several internal and terminal alkynes. Despite the lack of desired intermolecular reactions, DFT calculations of putative catalyst intermediates appears to be a promising strategy for the design and prioritization of bifunctional catalysts for C C bond formation.

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Design and Synthesis of Oxazoline-Based Scaffolds for Hybrid Lewis Acid/Lewis Base Catalysis of Carbon–Carbon Bond Formation

Cited by 4 publications

References 28 publications

The Use of Lewis Acids for Repairing Chemoselectivity of the Organocatalyzed Morita‐Baylis‐Hillman Reaction

The Use of Lewis Acids for Repairing Chemoselectivity of the Organocatalyzed Morita‐Baylis‐Hillman Reaction

Computationally‐Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

DFT-assisted design and evaluation of bifunctional copper(I) catalysts for the direct intermolecular addition of aldehydes and ketones to alkynes

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