Stereoselective syntheses of 1H-imidazo[2,1-a]isoindole-2,5(3H,9bH)-diones

摘要

1H-Imidazo[2,1-a]isoindole-2,5(3H,9bH)-diones 6a–i are synthesized in 67–96% yields with high stereoselectivitiesn(de 88–99%, except 6e with a 58% de value) via intermolecular condensation of 2-formylbenzoic acid (5) and α-aminonamides 4a–i in the presence of a catalytic amount of toluene-p-sulfonic acid. Intermediates 4 are obtained in twonsteps from easily available chiral N-Boc-α-amino acids 1.