51992-34-8Relevant academic research and scientific papers
Sequential Intermolecular Radical Addition and Reductive Radical Cyclization of Tyrosine and Phenylalanine Derivatives with Alkenes via Photoinduced Decarboxylation: Access to Ring-Constrained γ-Amino Acids
Osaka, Kazuyuki,Usami, Ayuka,Iwasaki, Tomoya,Yamawaki, Mugen,Morita, Toshio,Yoshimi, Yasuharu
supporting information, p. 9480 - 9488 (2019/07/08)
Sequential radical addition to alkenes and reductive radical cyclization of phenylalanine and tyrosine derivatives via photoinduced decarboxylation furnished ring-constrained γ-amino acids under mild conditions. A variety of alkenes such as acrylamides and acrylic esters could be employed in the photoinduced radical cascade cyclization. The yields of the ring-constrained γ-amino acids are dependent on the electron-accepting ability and steric hindrance of the alkene used. The proposed sequential reaction can also be applied for direct tethering of dipeptides to yield unique ring-constrained tetrapeptides.
Titania-promoted carboxylic acid alkylations of alkenes and cascade addition-cyclizations
Manley, David W.,McBurney, Roy T.,Miller, Phillip,Walton, John C.,Mills, Andrew,O'Rourke, Christopher
, p. 1386 - 1398 (2014/03/21)
Photochemical reactions employing TiO2 and carboxylic acids under dry anaerobic conditions led to several types of C-C bond-forming processes with electron-deficient alkenes. The efficiency of alkylation varied appreciably with substituents in the carboxylic acids. The reactions of aryloxyacetic acids with maleimides resulted in a cascade process in which a pyrrolochromene derivative accompanied the alkylated succinimide. The selectivity for one or other of these products could be tuned to some extent by employing the photoredox catalyst under different conditions. Aryloxyacetic acids adapted for intramolecular ring closures by inclusion of 2-alkenyl, 2-aryl, or 2-oximinyl functionality reacted rather poorly. Profiles of reactant consumption and product formation for these systems were obtained by an in situ NMR monitoring technique. An array of different catalyst forms were tested for efficiency and ease of use. The proposed mechanism, involving hole capture at the TiO2 surface by the carboxylates followed by CO2 loss, was supported by EPR spectroscopic evidence of the intermediates. Deuterium labeling indicated that the titania likely donates protons from surface hydroxyl groups as well as supplying electrons and holes, thus acting as both a catalyst and a reaction partner.
Unconventional titania photocatalysis: Direct deployment of carboxylic acids in alkylations and annulations
Manley, David W.,McBurney, Roy T.,Miller, Phillip,Howe, Russell F.,Rhydderch, Shona,Walton, John C.
supporting information; experimental part, p. 13580 - 13583 (2012/10/08)
Under dry, anaerobic conditions, TiO2 photocatalysis of carboxylic acid precursors resulted in carbon-carbon bond-forming processes. High yields of dimers were obtained from TiO2 treatment of carboxylic acids alone. On inclusion of electron-deficient alkenes, efficient alkylations were achieved with methoxymethyl and phenoxymethyl radicals. In reactions with maleic anhydride or maleimides, phenoxyacetic acid produced chromenedione derivatives in addition to adducts. These photocatalytic reactions are simple and cheap to perform, and the TiO2 is easily removed by filtration. The anaerobic photocatalysis strategy offers a range of synthetic possibilities.
