Graduation Semester and Year
2015
Language
English
Document Type
Thesis
Degree Name
Master of Science in Chemistry
Department
Chemistry and Biochemistry
First Advisor
Junha Jeon
Abstract
Homologation of esters to α,β-unsaturated esters is a useful transformation in organic synthesis. We have developed a new approach for the Ir-catalyzed reductive Horner-Wadsworth-Emmons olefination of esters; a one-pot method for the transformation of esters to α,β-unsaturated esters utilizing silyl acetals as aldehyde equivalents followed by Horner-Wadsworth-Emmons olefination. Lewis based activation of silyl acetals formed by Ir-catalyzed hydrosilylation of esters initially generates putative penta-coordinate silicate acetals which fragment into aldehydes, silanes and alkoxides in situ. The alkoxides deprotonate phosphonate esters which subsequently react with the aldehydes to furnish α,β-unsaturated esters. This method is operationally simple compared with aluminium hydride-based reductive Horner-Wadsworth-Emmons olefination. Notably, Horner-Wadsworth-Emmons olefination of traditionally challenging substrates such as aryl, alkenyl and alkynl esters furnishes the corresponding α,β-unsaturated esters at room temperature with excellent stereoselectivities (E/Z > 20:1) and moderate to excellent yields (48–91%). This transformation will contribute to enhancing the utility of silyl acetals in synthetic chemistry.
Disciplines
Chemistry | Physical Sciences and Mathematics
License
This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License.
Recommended Citation
Dakarapu, Udaya Sree, "Studies On Reductive Horner-Wadsworth-Emmons Olefination Using Mixed Silyl Acetals" (2015). Chemistry & Biochemistry Theses. 99.
https://mavmatrix.uta.edu/chemistry_theses/99
Comments
Degree granted by The University of Texas at Arlington