Date of Graduation
Summer 2017
Degree
Master of Science in Chemistry
Department
Chemistry and Biochemistry
Committee Chair
Matthew Siebert
Abstract
Propargylic acetates can lead to complex transformations upon exposure to a gold catalyst. Gold catalyzed transformations also allow for simple synthesis of a number of natural products. Gold (III)-cycloisomerization of a 5-acetoxy-1,6-enyne is reported to proceed through two pathways that differ in the order of major events: cyclization followed by ester migration (“cyclization first”) or the reverse (“migration first”). Both pathways could theoretically proceed in either order. This rearrangement is called the Ohloff-Rautenstrauch rearrangement and has high regio- and stereocontrol affording a bicylo[4.1.0]heptane carbon substructure. This rearrangement allows for the synthesis of the carene class of natural products. Computational modeling determining the mechanism and preference for the pathways in the gas- and solvent-phase (dichloroethane, IEFPCM) are described herein. Structures for the pathways are found using the B2PLYP/6-31G(d)-LANL2DZ model chemistry while energies are found at the B2PLYP-D3/def2TZVP//B2PLYP/6-31G(d)-LANL2DZ level. Both pathways feature multiple steps with low energy barriers. Highest-energy structures for both pathways are close in energy (ΔΔE‡ = 2.8 kcal/mol for solvent phase). Turnover frequency for each pathway are calculated suggesting that the cyclization first pathway may dominate.
Keywords
DFT, gold (III), propargylic acetate, carene, natural products
Subject Categories
Organic Chemistry | Physical Chemistry
Copyright
© Jeremy M. Hines
Recommended Citation
Hines, Jeremy M., "Electronic Structure Evaluation of Competing Pathways in the Gold(III)-Catalyzed Ohloff-Rautenstrauch Cyclosimerization Converting Propargylic Acetates to Carene-like Natural Products" (2017). MSU Graduate Theses. 3111.
https://bearworks.missouristate.edu/theses/3111
