Synthesis of Trifunctionalized Naphtho[1,2‑b]furans Based on the Strategy for the Construction of Both Furan and Naphthalene Cycle

Pd­(PPh3)2Cl2-catalyzed selective tandem cyclization/oxidation of available conjugated diazo ene-yne-ketones under O2 atmosphere led to the formation of diazo trisubstituted furans. The Rh2(OAc)4-mediated selective C­(sp2)–H insertion at the ortho-position of 2-aryl group (R1) of the furan moiety under N2 atmosphere occurred to construct naphthalene cycle, affording trifunctionalized naphtho­[1,2-b]­furans. C­(sp2)–H insertion at the 4-position of the furan ring, and Wolf rearrangement of diazo moiety have not been observed.