Ruthenium(II)-Catalyzed C-H Annulation of Mandelic Acids with Internal Alkynes to Construct Isocoumarins

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.

Automated summary

A series of isocoumarins were successfully synthesized through a one-pot cyclization reaction using mandelic acids and internal alkynes as raw materials, [RuCl2(p-cymene)](2) as the catalyst, and Cu(OAc)(2).H2O as the oxidant under reflux conditions in air. The established reaction conditions allowed for the exploration of various substrates, and it was found that aromatic aldehydes and aromatic acids also reacted smoothly in the system, providing moderate yields of the target products. Additionally, it was demonstrated that mandelic acids were converted into the corresponding benzoic acids as intermediates in the reaction.