The Chemistry of Phthalide-3-carboxylic Acid. V. The Reaction of the Acid With Imines

Abstract

Phthalide-3-carboxylic acids decarboxylate readily in the presence of imines, the product depending on the solvent used. In dimethyl sulfoxide, or in the absence of solvent, at 130º, the product is the 3-alkyl 3-hydroxyisoindolone or its dehydration product, but in acetic anhydride at 130º the product is a mixture of diastereoisomeric 3-acetylarninoalkylphthalides. The reactions can be applied to the synthesis of natural products such as the isoindoloisoquinoline and phthalideisoquinoline alkaloids.