A series of isocoumarins were synthesized by a one-pot cyclization reaction with mandelic
acids and internal alkynes as raw materials, [RuCl2(p-cymene)]2 as a catalyst, and Cu(OAc)2·H2O as an oxidant under reflux conditions in air. By using the established efficient
and reliable reaction conditions, a range of substrates were explored, and it was
found that both aromatic aldehydes and aromatic acids also reacted smoothly in this
system to give moderate yields of the target products. Furthermore, the mandelic acids
were shown to be converted into the corresponding benzoic acids as intermediates in
the reaction.
Key words
ruthenium catalysis - mandelic acids - alkynes - annulation - isocoumarins