Synthesis of phthalides utilizing a one-pot intramolecular domino protocol

Abstract

A number of (E)-3-alkylidine-phthalide derivatives have been prepared at room temperature in excellent yields in a one-pot reaction by treating o-alkenylbenzoic acids with meta-chloroperbenzoic acid and para-toluenesulfonic acid. This reaction presumably occurs via domino epoxidation – intramolecular cyclization – acid catalyzed dehydration sequence of reactions. On the other hand, 3-(2-formyl-3,4-dihydro-naphthalen-1-yl)-acrylic acid esters and 3-(2-formyl-3,4-dihydro-naphthalen-1-yl)-acrylonitriles afforded phthalide derivatives under Pinnick reaction conditions involving oxidation-intramolecular Michael addition.