Ti(OiPr)4‑Facilitated Formal Deoxygenative Annulation of Alkynyl 1,2-Diketones for the Synthesis of Highly Functionalized Furans

A unique deoxygenative cyclodimerization of alkynyl 1,2-diketones facilitated by Ti­(OiPr)4 is achieved, affording a series of highly functionalized furan products. An unusual C–C bond and CO bond cleavage of the substrates is observed, and Ti­(OiPr)4 plays triplicate roles in the reaction. Furthermore, the products show uncommon fluorescent emission in the solid state, indicating the potential practical applications of this work.