achieved via photocatalysis. This protocol exhibits a broad scope of lignin models and excellent compatibility of functionalization reagents, constructing a series of functionalized lignin-based aromatic compounds. Highly selective formation of alkyl radical species through a proton-coupled electrontransfer and β-scission process provides the opportunity to form new C–C and C–N bonds by reaction with
Unconventional Titania Photocatalysis: Direct Deployment of Carboxylic Acids in Alkylations and Annulations
作者:David W. Manley、Roy T. McBurney、Phillip Miller、Russell F. Howe、Shona Rhydderch、John C. Walton
DOI:10.1021/ja306168h
日期:2012.8.22
Under dry, anaerobic conditions, TiO2 photocatalysis of carboxylic add precursors resulted in carbon-carbon bond-forming processes. High yields of dirners 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.