The ruthenium-catalyzed intermolecular cascade cyclization of aromatic acids with aromatic aldehydes, which involves the direct insertion of C–H bond into a polar C=O bond and the successive intramolecular nucleophilic substitution, was developed for the synthesis of 3-substituted phthalides in good to excellent yields. This one-pot procedure characterizes in a short reaction time, the cheaper Ru(II) as a catalyst, readily available acids and aldehydes as starting materials, and water as the only theoretical by-product.These merits make the protocol an efficient and cost-effective route for the synthesis of 3-substituted phthalides.
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