Trialkylsilanes are important building blocks in organic synthesis;however,their widespread use in redox chemistry is limited by their high oxidation potentials and comparably high bond dissociation energies(BDEs)of S...Trialkylsilanes are important building blocks in organic synthesis;however,their widespread use in redox chemistry is limited by their high oxidation potentials and comparably high bond dissociation energies(BDEs)of Si-H and α-Si-C-H bonds(>92 kcal mol^(−1)).Herein,we report a new strategy for Si-H bond homolysis enabled by the synergistic combination of electrooxidation,photoinduced ligand-to-metal charge transfer(LMCT),and radical-mediated hydrogen atom transfer(HAT).Governed by the polarity-matching effect,the HAT to electrophilic MeO·or[Cl-OHCH_(3)]·from the more hydridic Si-H instead of a C-H bond allows the selective generation of silyl radicals.This electrophotocatalytic protocol provides rapid access to Si-functionalized benzimidazo-fused isoquinolinones with broad functional-group compatibility.Mechanistic studies have shown that n-Bu_(4)NCl is essential to the electrooxidation of CeCl_(3) to form the Ce(Ⅳ)species.展开更多
基金supported by grants from the National Key Technology R&D Program(no.2017YFB0307502)the National Natural Science Foundation of China(no.21871019)Beijing Municipal Education Committee Project(nos.KZ202110005003 and KM202110005006).
文摘Trialkylsilanes are important building blocks in organic synthesis;however,their widespread use in redox chemistry is limited by their high oxidation potentials and comparably high bond dissociation energies(BDEs)of Si-H and α-Si-C-H bonds(>92 kcal mol^(−1)).Herein,we report a new strategy for Si-H bond homolysis enabled by the synergistic combination of electrooxidation,photoinduced ligand-to-metal charge transfer(LMCT),and radical-mediated hydrogen atom transfer(HAT).Governed by the polarity-matching effect,the HAT to electrophilic MeO·or[Cl-OHCH_(3)]·from the more hydridic Si-H instead of a C-H bond allows the selective generation of silyl radicals.This electrophotocatalytic protocol provides rapid access to Si-functionalized benzimidazo-fused isoquinolinones with broad functional-group compatibility.Mechanistic studies have shown that n-Bu_(4)NCl is essential to the electrooxidation of CeCl_(3) to form the Ce(Ⅳ)species.
