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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

preprint
revised on 19.01.2020 and posted on 21.01.2020 by Eric Greve, Jacob D. Porter, Chris Dockendorff
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 aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that 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. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (t-Bu)PyBOX-Pt2+complex, but neither were the desired C-C bond formations observed under several different conditions.

Funding

American Chemical Society Petroleum Research Fund (55732-DNI1)

Marquette University Arthur J. Schmitt Fellowship (for E.G.)

History

Email Address of Submitting Author

christopher.dockendorff@mu.edu

Institution

Marquette University

Country

United States

ORCID For Submitting Author

0000-0002-4092-5636

Declaration of Conflict of Interest

None

Version Notes

Version 2 (submitted Jan. 19, 2020) contains details of a successful intramolecular reaction, plus additional DFT calculations.

Exports