Experimental and Theoretical Studies on Iron-Promoted Oxidative Annulation of Arylglyoxal with Alkyne: Unusual Addition and Migration on the Aryl Ring

  • J Am Chem Soc. 2017 Nov 29;139(47):17015-17021. doi: 10.1021/jacs.7b05981.
Chen-Hsun Hung  1 ,  Parthasarathy Gandeepan  1 ,  Lin-Chieh Cheng  1 ,  Liang-Yu Chen  2 ,  Mu-Jeng Cheng  2 ,  Chien-Hong Cheng  1
Affiliations
  • 1. Department of Chemistry, National Tsing Hua University , Hsinchu 30013, Taiwan.
  • 2. Department of Chemistry, National Cheng Kung University , Tainan 701, Taiwan.
PMID: 29088912 DOI: 10.1021/jacs.7b05981
Abstract

An Fe(III)-promoted oxidative annulation reaction was developed for the synthesis of 1,2-naphthoquinones. A variety of substituted arylglyoxals and internal alkynes undergo the transformation in the presence of FeCl3 at room temperature to afford the 1,2-naphthoquinone products in good yields in a short reaction time. Interestingly, the products show unusual pseudomigration of the substituent on the arene ring of arylglyoxals. A possible mechanism involving Fe(III)-promoted formation of a vinyl cation from arylglyoxal and alkyne, electrophilic addition of the vinyl cation to the ipso carbon of the aryl group to give a spiral intermediate, and then migration of the keto carbon to the ortho carbon was proposed as key steps and verified using quantum mechanics.

Products