Co-Authors:
Veierov, D., Departments of Organic and Structural Chemistry, Weizmann Institute of Science, Rehovot, Israel
Bercovici, T., Departments of Organic and Structural Chemistry, Weizmann Institute of Science, Rehovot, Israel
Fischer, E., Departments of Organic and Structural Chemistry, Weizmann Institute of Science, Rehovot, Israel
Mazur, Y., Departments of Organic and Structural Chemistry, Weizmann Institute of Science, Rehovot, Israel
Yogev, A., Departments of Organic and Structural Chemistry, Weizmann Institute of Science, Rehovot, Israel
Abstract:
1,3-Dicarbonyl compounds II, which exist in hydrocarbon solvents predominantly in the chelated enol form I, are shown by flash photolysis to undergo facile photoisomerization to the corresponding nonchelated and short-lived enol form III (Scheme I), whose existence and UV absorption spectra are reported here for the first time. The III isomers are thermally unstable and revert spontaneously to either I (diketones), II (ethyl acetoacetate), or both (ethyl benzoylacetate). A UV-induced low-yield photoconversion I → II and the reverse thermal reaction are observed with stationary spectrophotometric methods.