Browsing by Author "Jagadesan, Pradeepkumar"
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- Competing pathways for photoremovable protecting groups: the effects of solvent, oxygen and encapsulationPublication . Field, Thomas; Peterson, Julie; Ma, Chicheng; Jagadesan, Pradeepkumar; Da Silva, José Paulo; Rubina, Marina; Ramamurthy, V.; Givens, Richard S.Extending the applications of Photoremovable Protecting Groups (PPGs) to "cage" phenols has generally met with unusually complex PPG byproducts. In this study, we demonstrate that thep-hydroxyphenacyl (pHP) cage for both simple and complex phenolics, including tyrosine, dispenses free phenols. With the simpler unsubstituted phenols, the reaction is governed by their Bronsted Leaving Group ability. On the other hand, the byproducts of the cage vary with these phenols. For the more acidic phenols the cage byproduct follows the Favorskii rearrangement to formp-hydroxyphenylacetic acid whereas for the weaker phenols other reactions such as reduction and hydrolysis begin to emerge. When the photolysis is conducted in octa acid (OA) containers, non-Favorskii, unrearranged fragments of the cage and other byproducts arise.
- Photorelease of incarcerated guests in aqueous solution with phenacyl esters as the triggerPublication . Jagadesan, Pradeepkumar; Silva, José P. da; Givens, Richard S.; Ramamurthy, V.We report the clean, efficient photorelease of a series of carboxylic acids embedded in octa acid (OA) host and protected by a p-hydroxyphenacyl cage. A key role is played by the cage by providing hydrophobicity for entry into the OA enclosure and yet readily removable as a photoactivated protecting group for release from the host. The rapid photo-Favorskii rearrangement of the departing chromophore does not react with the host OA but diminishes hydrophobicity of the OA contents, leading to their facile release into the solvent.
- Release of guests from encapsulated masked hydrophobic precursors by a phototriggerPublication . Jayaraj, Nithyanandhan; Jagadesan, Pradeepkumar; Samanta, Shampa R.; Silva, José P. da; Ramamurthy, V.Examples of release of organic acids from encapsulated p-methoxyphenacyl esters provided here demonstrate the value of a phototrigger strategy to release chemicals of interest in water from hydrophobic precursors. In this study, a photochemical beta-cleavage process centered on the p-methoxyphenacyl group is exploited to release the acid of interest from a water-soluble capsule made up of octa acid.