Acid-catalyzed synthesis of 2,3-dihydronaphtho[2,3-b]furan and 3,4-dihydro-2H-benzo[g]chromene derivatives

p-Toluenesulfonic acid-promoted organic transformations for the generation of molecular complexity

“…93 Additionally, naphthofurans have also been significantly use as a potential organic semiconductor material for bilayer organic photovoltaics, organic light-emitting diodes, and organic field-effect transistors. 94 Prof. Oh found 95 that p -TSA is useful as a very effective catalyst for the synthesis of 3,4-dihydro-2 H -benzo[ g ]chromene and 2,3-dihydronaphtho[2,3- b ]furan from readily accessible ortho -keto-, ortho -oxalate-, and ortho -formyl arylacetylenols through a domino cyclization process (Scheme 59). A cyclic oxinium ion intermediate A33 could be formed after protonation of the starting substrate, which further reacted with water, followed by intramolecular cyclization/ring opening, generating dihydrofuran intermediate A34 .…”