Master of Science (MS)
Semester of Degree Completion
T. Howard Black
3-Phenylbenzofuranone, when deprotonated with sodium hydride, forms an extended enolate system which, when treated with excess alkyl chloroformates, affords only oxygen-acylated products, as opposed to the usually desired carbon-functionalized derivatives. It was discovered that such molecules, when treated with a catalytic amount of 4- (N, N-dimethylamino)pyridine (DMAP), rearrange quantitatively to the carbon acylated isomers.
These migrations, which are accompanied by a deep blue color, are proposed to involve a reactive intermediate. This intermediate, which is postulated as an ion pair charge transfer (IPCT) complex, has been closely studied in order to gain a better understanding of the rearrangement mechanism. The spectral data was obtained while the rearrangement was going on, and the lifetime of the reactive intermediate was found to be less than 15 seconds.
The rearrangement times and colors of this intriguing reaction were observed by substituting various substituents on the 3-Phenylbenzofuranone ring system. The λmax values of the reaction color, with various substituents on 3-Phenylbenzofuranone ring system, were correlated with the Hammett substituent constants.
Boppisetti, Jagadish K., "DMAP as a Catalyst for Carbon Acylation: Elucidation of Mechanistic Pathway, Including Spectral Characterization of the Putative Reactive Intermediate" (2003). Masters Theses. 1487.