Recent Advances in Vinyl Radical-Mediated Hydrogen Atom Transfer
Baitong Yue, Xinxin Wu, Chen Zhu
Abstract
In recent years, vinyl radical-mediated hydrogen atom transfer (HAT) has received increasing attention. This protocol provides an efficient pathway for radical cyclization and regioselective C(sp 3 )-H bond functionalization including vinylation, alkynylation, halogenation, arylation, etc. Generally, vinyl radicals are generated from single electron reduction of vinyl halides or the addition of extra radical to alkynes. The reaction pathways depend on substrates. For example, the resulting alkyl radical arising from vinyl radical-mediated HAT process is prone to be intramolecularly re-added to alkene, leading to cyclic products. When employing specific propargyl alcohols as substrates, the cyclic alkyl radical intermediate undergoes -scission of C-C bond to realize vinyl migration. In addition, intermolecular radical trapping usually occurs by using internal alkynes. The transformation based on vinyl radical-mediated HAT features high regioselectivity, good atom-economy, and broad diversity of reaction modes. The recent advances in the research area are summarized.