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@article{842154, author = {Stensrud, Kenneth F. and Noh, Jihyun and Kandler, Karl and Wirz, Jakob and Heger, Dominik and Givens, Richard}, article_number = {15}, keywords = {RESOLVED RESONANCE RAMAN; PHOTOREMOVABLE PROTECTING GROUPS; DENSITY-FUNCTIONAL THEORY; TRIPLET-STATE; EXCITED-STATE; PHOTODEPROTECTION; SPECTROSCOPY; HYDROXYACETOPHENONE; ABSORPTION; ACTIVATION}, language = {eng}, issn = {0022-3263}, journal = {JOURNAL OF ORGANIC CHEMISTRY}, title = {Competing Pathways in the Photo-Favorskii Rearrangement and Release of Esters: Studies on Fluorinated p-Hydroxyphenacyl-Caged GABA and Glutamate Phototriggers}, volume = {74}, year = {2009} }
TY - JOUR ID - 842154 AU - Stensrud, Kenneth F. - Noh, Jihyun - Kandler, Karl - Wirz, Jakob - Heger, Dominik - Givens, Richard PY - 2009 TI - Competing Pathways in the Photo-Favorskii Rearrangement and Release of Esters: Studies on Fluorinated p-Hydroxyphenacyl-Caged GABA and Glutamate Phototriggers JF - JOURNAL OF ORGANIC CHEMISTRY VL - 74 IS - 15 SP - 5219-5227 EP - 5219-5227 SN - 00223263 KW - RESOLVED RESONANCE RAMAN KW - PHOTOREMOVABLE PROTECTING GROUPS KW - DENSITY-FUNCTIONAL THEORY KW - TRIPLET-STATE KW - EXCITED-STATE KW - PHOTODEPROTECTION KW - SPECTROSCOPY KW - HYDROXYACETOPHENONE KW - ABSORPTION KW - ACTIVATION N2 - Three new trifluoromethylated p-hydroxyphenacyl (pHP)-caged gamma-aminobutyric acid (GABA) and glutamate (Glu) derivatives have been examined for their efficacy as photoremovable protecting groups in aqueous solution. Through the replacement of hydrogen with fluorine, e.g., a m-trifluoromethyl or a m-trifluoromethoxy versus m-methoxy substituents on the pHP chromophore, modest increases in the quantum yields for the release of amino acids GABA and glutamate as well as improved lipophilicity were realized. The pH P triplet undergoes a photo-Favorskii rearrangement with concomitant release of the amino acid substrate. Deprotonation competes with the rearrangement from the triplet excited state and yields the pHP conjugate base that, upon reprotonation, regenerates the starting ketoester, a chemically unproductive or "energy-wasting" process. When picosecond pump-probe spectroscopy is employed, GABA derivatives 2-5 are characterized by short triplet lifetimes, a manifestation of their rapid release of GABA. The bioavailability of released GABA at the GABA(A) receptor improved when the release took place from m-OCF3 (2) but decreased for m-CF3 (3) when compared with the parent pHP derivative. These studies demonstrate that pK(a) and lipophilicity exert significant but sometimes opposing influences on the photochemistry and biological activity of pHP phototriggers. ER -
STENSRUD, Kenneth F., Jihyun NOH, Karl KANDLER, Jakob WIRZ, Dominik HEGER a Richard GIVENS. Competing Pathways in the Photo-Favorskii Rearrangement and Release of Esters: Studies on Fluorinated p-Hydroxyphenacyl-Caged GABA and Glutamate Phototriggers. \textit{JOURNAL OF ORGANIC CHEMISTRY}. 2009, roč.~74, č.~15, s.~5219-5227. ISSN~0022-3263.
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