Yb(OTf)3-Catalyzed Alkyne–Carbonyl Metathesis–Oxa-Michael Addition Relay for Diastereoselective Synthesis of Functionalized Naphtho[2,1-b]furans

A new Lewis acid catalyzed alkyne–carbonyl metathesis/oxa-Michael addition relay was first reported, leading to the atom-economic synthesis of unreported functionalized indolone-containing naphtho[2,1-b]furan-1-ones with a quaternary center in good to excellent yields and high diastereoselectivity through scission/recombination of C–O double bonds under the mild conditions. A Yb(OTf)3-catalyzed reaction between α-alkynyl naphthalen-2-ols and isatins worked efficiently and offered a convergent and regioselective protocol to construct cyclic ketones via alkyne polyfunctionalization.