Steady-state and time-resolved studies on the formation of skatolyl radicals photosensitized by 2-henzoylthiophene

摘要

Quenching of the excited triplet state of 2-benzoylthiophene (BT)by 3-methylindole (CH_3InH)leads to several neutral radicals resulting from formal hydrogen-atom abstraction.The transient absorptin spectra of the BT ketyl radical (BTH)and the N-centered (CH_3In)radial are directly detected by laser flash photolysis.From the differences between the spectra in the presence and the absence of oxygen,the C-centered skatolyl radical (CH_2InH)is also observed.Accordingly,product studies bemonstrate the formation of homodimers as well as cross-coupling products.They include BTh dimers (BTH-BTH,two stereoisomers),indolyl dimers (three different products)and products sderived from reaction of skatolyl and BT ketyl radicals.