Tandem intramolecular Diels–Alder/retro-Diels–Alder cycloaddition of 2H-chromen-2-one as dienes with the expulsion of CO_2

摘要

To study the intramolecular Diels-Alder cycloadditon of 2H-chromen-2-one as a diene,a series of chiral N-allyl-N-benzylamides that contain a 2H-chromen-2-one moiety were designed for the synthesis of benzo[f]isoindol-l-ones via an intramolecular Diels-Alder and a subsequent retro-Diels-Alder cycloaddition with the expulsion of CO_2.Both the yield(80%-89%) and absolute stereocontrol of the tandem reaction were high when an electron-withdrawing group was attached to the dienophile.The double bond in the styrene substructure remained in the products could be further derivatized by dihydroxylation.