title: Photoenolization of o-Methylvalerophenone Ester Derivative.
abstract: Photolysis of ester 1 in argon-saturated methanol and acetonitrile does not produce any product, whereas irradiation of 1 in oxygen-saturated methanol yields peroxide 2. Laser flash photolysis studies demonstrate that 1 undergoes intramolecular H atom abstraction to form biradical 3 (λmax ~340 nm), which intersystem crosses to form photoenols Z-4 and E-4 (λmax ~380 nm). Photoenols 4 decay by regenerating ester 1. With the aid of density functional theory calculations, it was concluded the photoenol E-4 does not undergo spontaneous lactonization or electrocyclic ring closure because the transition state barriers for these reactions are too large to compete with reketonization of E-4 to form 1.
authors.affiliation: Department of Chemistry, University of Cincinnati, Cincinnati, OH.
authors.forename: Anushree
authors.initials: A
authors.lastname: Das
authors.affiliation: Department of Chemistry, University of Cincinnati, Cincinnati, OH.
authors.forename: Emily A
authors.initials: EA
authors.lastname: Lao
authors.affiliation: Department of Chemistry, University of Cincinnati, Cincinnati, OH.
authors.forename: Anna D
authors.initials: AD
authors.lastname: Gudmundsdottir