title: Competing isomerizations: a combined experimental/theoretical study of phenylpentenone isomerism.
abstract: The possible competition of Z/E versus hydrogen-shift isomerization in (E)-5-phenyl-3-penten-2-one (E-1) and (E)-5-phenyl-4-penten-2-one (E-2) was studied, both experimentally and theoretically. Iodine-catalyzed isomerization experiments and computational modeling studies show that the equilibrated system consists predominantly of E-1 and E-2, with E-2 in moderate excess, and with no detectable amounts of the Z (cis) diastereoisomers. Density functional theory (DFT) calculations corroborated the free energy difference (Delta(r) and Delta(r) were -0.7 and -1.1 kcal mol(-1), respectively), and computations of Boltzmann-weighted (1)H NMR spectra were found to be useful in confirming the assignment of the isomers. The relevance of this equilibrium to earlier work on double-bond stabilization is discussed.
authors: Department of Chemistry and Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.
authors: Zhongyi
authors: Z
authors: Wang
authors: Andrew G H
authors: AG
authors: Wee
authors: Steven S
authors: SS
authors: Hepperle
authors: Ron G
authors: RG
authors: Treble
authors: Allan L L
authors: AL
authors: East