C−O Bond Fragmentation of 4-Picolyl- and N-Methyl-4-picolinium Esters Triggered by Photochemical Electron Transfer
摘要:
Photochemical reduction of several 4-picolyl- and N-methyl-4-picolinium esters was examined using product analysis, laser flash photolysis, and fluorescence quenching. It is demonstrated that the radical (anions) formed in these reactions readily fragment to yield a carboxylic acid and a 4-pyridylmethyl radical intermediate. The high chemical and quantum yields observed for these photoreactions suggests that these esters can be used as photolabile protecting groups.
Photolytic Release of Carboxylic Acids Using Linked Donor−Acceptor Molecules: Direct versus Mediated Photoinduced Electron Transfer to <i>N</i>-Alkyl-4-picolinium Esters
作者:Chitra Sundararajan、Daniel E. Falvey
DOI:10.1021/ol050744n
日期:2005.6.1
[reaction: see text] Efficient photorelease (Phi = 0.7) of carboxylic acids is achieved with a covalently linked mediator (benzophenone) protecting group (N-alkyl-4-picolinium ester) molecule. The mechanism involves initial photoreduction of the mediator, followed by rapid electrontransfer to the protecting group.
Photorelease of Carboxylic Acids, Amino Acids, and Phosphates from <i>N</i>-Alkylpicolinium Esters Using Photosensitization by High Wavelength Laser Dyes
作者:Chitra Sundararajan、Daniel E. Falvey
DOI:10.1021/ja050760f
日期:2005.6.1
Visible light (>450 nm) is used to efficiently cleave carboxylic acids, aminoacids, and phosphates from their N-methyl picolinium esters. Photolysis using pyrromethene dyes PM 546 and PM 597 and also coumarin 6 as photosensitizers effects release of carboxylic acids, N-protected aminoacids, and phosphates in quantitative yields. The effective rate of photorelease by the dyes, Phiepsilon, was found
New two- and three-cationic polymethine dyes. Synthesis, properties and application
作者:Janina Kabatc、Katarzyna Jurek
DOI:10.1016/j.dyepig.2014.06.016
日期:2015.1
applied as visiblelightinitiators for acrylic monomer polymerization. In the photoinitiating system, the polymethine dye cation acts as an electron acceptor whereas borate anion is an electron donor. The actual photoinitiators can only operate in a restricted part of the visiblelight region; as a consequence, a several photoinitiators are usually necessary to harvest all the emitted visible photons
C−O Bond Fragmentation of 4-Picolyl- and <i>N</i>-Methyl-4-picolinium Esters Triggered by Photochemical Electron Transfer
作者:Chitra Sundararajan、Daniel E. Falvey
DOI:10.1021/jo049501j
日期:2004.8.1
Photochemical reduction of several 4-picolyl- and N-methyl-4-picolinium esters was examined using product analysis, laser flash photolysis, and fluorescence quenching. It is demonstrated that the radical (anions) formed in these reactions readily fragment to yield a carboxylic acid and a 4-pyridylmethyl radical intermediate. The high chemical and quantum yields observed for these photoreactions suggests that these esters can be used as photolabile protecting groups.