Francoise Henin, Stephane Letinois, Jacques Muzart, Jakob Wirz, "Flash-photolytic generation of dienols and dienolates from alpha,beta-unsaturated esters and kinetics of their amine-catalyzed ketonization in nonaqueous media", Photochem. Photobiol. Sci. 2006, 5, 426-431.

Abstract: Dienols of alpha,beta--unsaturated esters were generated and observed by flash photolysis and their decay rates in acetonitrile and in hexane solutions were measured in the presence of amines or aminoalcohols. In acetonitrile, 1:1 ammonium dienolate transient intermediates were observed. In hexane, no dienolate could be detected and two moles of the inductor participated in the rate-determining step for tautomerization.