Synthesis of 4-Arylisocoumarins (=4-Aryl-1H-2-benzopyran-1-ones) through Acidic Hydrolysis of (Z)-2-(1-Aryl-2-methoxyethenyl) benzaldehydes, Followed by Oxidation

4-Arylisocoumarins (=4-aryl-1H-2-benzopyran-1-ones) 6 were prepared from 2-(1-aryl-2-methoxyethenyl)-1-bromobenzenes 1. Successive treatment of these bromo styrenes with BuLi and 1-formylpiperidine gave a mixture of (E)- and (Z)-2-(1-aryl-2-methoxyethenyl)benzaldehydes 2. Hydrolysis of (Z)-isomers with conc. HBr, followed by pyridinium chlorochromate (PCC) oxidation of the resulting 1H-2-benzopyran-1-ol derivatives 4 (and 5), afforded the desired products.