3-benzoyl-4-hydroxyisochromen-1-one derivatives, their synthesis and synthetic application

3-Benzoyl-1,4-isochromandione derivatives were prepared by cyclization of phenacyl phthalates (2). The cyclization was done in the presence of N-methylpyrrolidone and potassium hydroxide. These compounds served as intermediates for the synthesis of more complicated isocoumarine derivatives. A Wittig reaction with (carbethoxymethylene)triphenyl phosphorane was conducted in a microwave reactor and resulted in the formation of substituted 4-phenylpyrano[3,2-c]isochromene-2,6-dione