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Light-promoted borylation and lactonization of propargyl acetates using NHC-borane
Hangcheng Ni1, Yu Li2, Chaoming Li3
1College of Pharmacy, Jinhua University of Vocational Technology Jinhua 321007 People's Republic of China nihc@hotmail.com liuzhenxiang86@163.com.
Abstract:
In the absence of photoredox catalyst (PC), we have successfully achieved radical borylation and lactonization of propargyl acetates under light irradiation using N-heterocyclic carbene borane (NHC-borane), leading to the synthesis of various substituted 4-(NHC-boryl)-2(5H)-furanones. The reaction is triggered from the generation of an NHC-boryl radical, which is formed via hydrogen atom transfer (HAT) of NHC-borane with tert-butyl peroxide derived from the light-induced homolytic cleavage of di-tert-butyl peroxide (DTPB). During the lactonization process, carbon boron formation, carbon-carbon bond formation and cleavage are observed. This approach offers a facile and mild method for the construction of borylated furanones, opening a new possibility in radical borylation chemistry.
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