Efficient One-Pot Synthesis of 3-Substituted Phthalides via Additive Arylation of Organozinc Intermediate

In recent years, substitution at the third position on phthalides has been proven a valuable synthetic intermediate for developing active molecules. We reported a direct and efficient onepot method for the synthesis of 3-aryl Phthalides performed by adding organo-zinc reagent on methyl-2-formylbenzoate; reagent formed in-situ by the reaction between diethylzinc and different aryl boronic acid derivatives without using any ligand. The possible mechanism involved a coordinated zinc carbonyl transition state, arylation, and followed by the intramolecular cyclization. The substituents groups in boronic having different electronic and steric properties played an important role in the reaction completion time and yield. The structure elucidation and confirmation of the synthesized compounds were done by using H-NMR analytical data. The method can be useful for synthesizing various scaffolds and intermediates in search of potentially active compounds.