A highly efficient and convenient procedure to access a series of coumarin-containing
phthalides and derivatives is developed. The novel bis-heterocyclic products are obtained
via reactions between 4-hydroxycoumarins (or 4-hydroxy-2-quinolones) with different
2-formylbenzoic acids in water as an environmentally friendly solvent. 4-Aryl substituted
derivatives of 3-(4-hydroxy)coumarinylphthalide are obtained in excellent yields by
initial conversion into the corresponding triflate and subsequent palladium-catalyzed
Suzuki–Miyaura coupling with arylboronic acids.
Key words
coumarins - phthalides - bis-heterocyclic - water - Suzuki–Miyaura coupling