Exploratory Photochemistry: Pushing the Boundaries of the p-Hydroxyphenacyl Photoremovable Protecting Group

Abstract

Abstract Exploratory Photochemistry: Pushing the Boundaries of the p-Hydroxyphenacyl Photoremovable Protecting Group A. Exploratory and Mechanistic Photochemistry B. Novel Applications of the p-Hydroxyphenacyl Photoremovable Protecting Group By Chamani Perera, Ph.D. Department of Chemistry, November 2009 University of Kansas The p-hydroxyphenacyl (pHP) chromophore is an attractive addition to the family of photoremovable protecting groups in chemistry and biology. Substituent effects on the pHP moiety were explored using cyano substituent at otho and para positions, employing GABA and acetate leaving groups. The quantum yield for GABA release from 3-cyano pHP GABA in water was substantially higher (0.42) than that for the parent. Two novel applications of pHP photochemistry were demonstrated. A light sensitive release of a fluorophore from an almost non-fluorescent pHP fluorophore quencher ensembles resulted in regenerated fluorescence upon exposure to ultraviolet radiation. Carbazole as the quencher leaving group drove the photorelease toward an electron-transfer, radical mechanism. A second application demonstrated that fluorophilic pHP derivatives obtained by attaching a fluorous chain, could be employed to separate the products, often in 95-100% yield, after photorelease from the cage by using fluorous solid phase extraction and fluorous liquid-liquid extraction separation technology.