Microwave- and ultrasound-assisted semisynthesis of natural methoxylated propiophenones from isomeric mixture of phenylpropenes in minutes

A rapid and practical semisynthesis of natural methoxylated propiophenones (3a–3f) is realized by reacting stereo- and regio-isomeric mixture of phenylpropenes (1a–1f) with a catalytic amount of palladium chloride – sodium formate in formic acid, methanol, and water (2:1:2) into single product phenylpropanes (2a–2f) followed by its oxidation with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in wet dioxane, containing a few drops of formic acid. Conventional, ultrasound, and microwave heating were compared through these studies.