DBU‐Catalyzed [3+2] Cycloaddition of Benzoaurones with 3‐Homoacyl Coumarins: Synthesis of Spiro[Benzofuranone‐Cyclopentane] Compounds

Abstract In the presence of organocatalyst DBU, novel spiro[benzofuranone‐cyclopentane] compounds are prepared via a [3+2] cycloaddition of benzoaurones with 3‐homoacyl coumarins. This method proceeds smoothly under mild conditions and shows tolerance for various substituent groups, affording the desired products in good yields with excellent diastereoselectivities.