A convenient and efficient synthesis of pyranoquinolinones was achieved using the ethylenediamine diacetate catalyzed reactions of 2,4-dihydroxyquinoline and a variety of α,β-unsaturated aldehydes in good yield. The key feature of these reactions is the formal [3+3] cycloaddition. This new methodology was applied successfully to the total synthesis of naturally occurring pyranoquinolinone alkaloids, zanthosimuline, cis-3′,4′-dihydroxy-3′,4′-dihydroflindersine, and orixalone D.
pyranoquinolinones - formal [3+3] cycloaddition - zanthosimuline -
cis-3′,4′-dihydroxy-3′4′-dihydroflindersine - orixalone D
