Visible-Light-Mediated Hydrosilylation Of Alkenes Via Decarboxylation Of Si-COOH

Due to their unique physicochemical properties,organosilicon compounds are widely used in synthetic chemistry,materials chemistry and medicinal chemistry.Therefore,the development of new strategies to construct C-Si bonds has been a research topic of great interest in organosilicon chemistry.Radical silicidation is an important synthetic strategy for the synthesis of silicon-containing compounds,and many radical initiators have been successfully used in radical silicidation in recent decades.However,most synthetic strategies still require the participation of peroxides or transition metals.As a common synthetic precursor,silane is widely used in synthetic chemistry.In this paper,a novel silicidation reaction using silicon carboxylic acid compounds as radical precursors was investigated.Firstly,the alkenes hydrosilation was realized through the synergistic strategy of photocatalysis and hydrogen atom transfer,the reaction conditions were optimized,and the optimal reaction conditions were finally determined:silicon carboxylic acid was used as the precursor of silicon radical,4CzIPN was used as the photocatalyst,and quinine was used as the photocatalyst.The ring was used as a hydrogen atom transfer catalyst,toluene was used as a solvent,and the target product was obtained in good yield under light and argon stirring for 24 hours.The reaction conditions have good functional group compatibility,and the reaction conditions are mild without the participation of metals.Subsequently,substrate expansion is performed under optimal reaction conditions.The reaction has good functional group tolerance and can tolerate substrates with different functional groups in the ortho and para positions of styrene at the same time.In addition,heteroaryl olefins and aliphatic olefins are also feasible substrates.Finally,17 compounds containing different functional groups were synthesized.functional groups of silicon compounds,and data were characterized by¹H NMR,¹³C NMR.Next,through a series of mechanism experiments of control experiments and free radical trapping,the possible catalytic cycle of the reaction was explored.It was speculated that Si-COOH decarboxylates to form silicon radicals under the synergistic effect of photoredox catalysis and hydrogen atom transfer catalysis,and then generates free radicals with alkenes.Addition realizes the reaction process of silicidation.Finally,a preliminary study of the derivatization reaction of silicon carboxylic acid as a silicon radical precursor.In the initial exploration under the same reaction conditions,cinnamic acid was used as a substrate to double decarboxylate silicon carboxylic acid to construct C-Si bond,and further research is being carried out in an orderly manner.