Synthesis of 3-aryl-7-nitro-3,4-dihydroisocoumarins from 4-nitrohomophthalic acid

4-Nitrohomophthalic acid reacts with aromatic aldehydes in the presence of piperidine to yield 3-aryl-7-nitro-3,4-dihydroisocoumarins. Under the same conditions, homophthalic acid yields stilbene-α,2-dicarboxylic acids.