| BOWNIK, Iwona Božena, Peter ŠEBEJ, Jaromír LITERÁK, Dominik HEGER, Zdeněk ŠIMEK, Richard S. GIVENS and Petr KLÁN. 4-Hydroxyphenacyl Ammonium Salts: A Photoremovable Protecting Group for Amines in Aqueous Solutions. The Journal of Organic Chemistry. ACS Publications, 2015, vol. 80, No 19, p. 9713-9721. ISSN 0022-3263. Available from: https://dx.doi.org/10.1021/acs.joc.5b01770. |
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@article{1314432,
author = {Bownik, Iwona Božena and Šebej, Peter and Literák, Jaromír and Heger, Dominik and Šimek, Zdeněk and Givens, Richard S. and Klán, Petr},
article_number = {19},
doi = {http://dx.doi.org/10.1021/acs.joc.5b01770},
keywords = {photochemistry; ammonium salts; photoremovable protecting group},
language = {eng},
issn = {0022-3263},
journal = {The Journal of Organic Chemistry},
title = {4-Hydroxyphenacyl Ammonium Salts: A Photoremovable Protecting Group for Amines in Aqueous Solutions},
url = {http://pubs.acs.org/doi/10.1021/acs.joc.5b01770},
volume = {80},
year = {2015}
}
TY - JOUR
ID - 1314432
AU - Bownik, Iwona Božena - Šebej, Peter - Literák, Jaromír - Heger, Dominik - Šimek, Zdeněk - Givens, Richard S. - Klán, Petr
PY - 2015
TI - 4-Hydroxyphenacyl Ammonium Salts: A Photoremovable Protecting Group for Amines in Aqueous Solutions
JF - The Journal of Organic Chemistry
VL - 80
IS - 19
SP - 9713-9721
EP - 9713-9721
PB - ACS Publications
SN - 00223263
KW - photochemistry
KW - ammonium salts
KW - photoremovable protecting group
UR - http://pubs.acs.org/doi/10.1021/acs.joc.5b01770
L2 - http://pubs.acs.org/doi/10.1021/acs.joc.5b01770
N2 - Irradiation of N-protected p-hydroxyphenacyl (pHP) ammonium caged derivatives at 313 nm releases primary and secondary amines or ammonia in nearly quantitative yields via the photo-Favorskii reaction when conducted in acidic or neutral aqueous buffered media. The reaction efficiencies are strongly dependent on the pH with the most efficient and highest yields obtained when the pH of the media maintains the ammonium and p-hydroxyl groups as their conjugate acids. For example, the overall quantum yields of simple secondary amines release are 0.5 at acidic pH from 3.9 to 6.6 dropping to 0.1 at neutral pH 7.0 and 0.01 at pH 8.4. Speciation studies provide an acid-base profile that helps define the scope and limitations of the reaction. When the pK(a) of the ammonium group is lower than that of the phenolic hydroxyl group, as is the case for the alpha-amino-protected amino acids, the more acidic ammonium ion deprotonates as the media pH is changed from acidic toward neutral or basic, thus diminishing the leaving group ability of the amino group. This, in turn, lowers the propensity for the photo-Favorskii rearrangement reaction to occur and opens the reaction pathway to alternative competing photoreduction process.
ER -
BOWNIK, Iwona Božena, Peter ŠEBEJ, Jaromír LITERÁK, Dominik HEGER, Zdeněk ŠIMEK, Richard S. GIVENS and Petr KLÁN. 4-Hydroxyphenacyl Ammonium Salts: A Photoremovable Protecting Group for Amines in Aqueous Solutions. \textit{The Journal of Organic Chemistry}. ACS Publications, 2015, vol.~80, No~19, p.~9713-9721. ISSN~0022-3263. Available from: https://dx.doi.org/10.1021/acs.joc.5b01770.
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