A Cycloisomerization/Friedel–Crafts Alkylation Strategy for the Synthesis of Pyrano[3,4-b]indoles
journal contributionposted on 05.08.2011, 00:00 by Matthew R. Medeiros, Scott E. Schaus, John A. Porco
The synthesis of pyrano[3,4-b]indoles is described. The reaction sequence involves Sonogashira coupling of dihydropyran propargyl ether scaffolds with iodoanilines to afford intermediate indoles. Lewis acid-catalyzed ionization of the dihydropyrans, followed by intramolecular C3 alkylation of the indole, provides the title compounds.