A novel method for the synthesis of isoflavones from coumarin analogues has been devised. This strategy involves the transformation of coumarins into halogenated hemiacetal ester analogues, followed by the installation of the B-ring of isoflavones via a classical Suzuki–Miyaura cross-coupling reaction. Subsequent simple hydrolysis affords the target isoflavones. The substrate scope with respect to both the A-ring and B-ring was evaluated, revealing that the method exhibits broad substrate tolerance. It was observed that the electronic properties of substituents on either ring A or ring B exerted no significant influence on the reaction efficiency, which can be rationalized by the push–pull electronic effect inherent to the hemiacetal ester intermediate. This approach enables the convergent synthesis of diverse isoflavone analogues and represents a valuable addition to the existing repertoire of synthetic methodologies for isoflavones.
Liu et al. (Sun,) studied this question.