Palladium‐Acid Co‐Catalyzed Cleavage of Alkynoates to Construct Dibenzo[c,h]xanthene Derivatives.

A novel palladium‐acid co‐catalyzed C(sp)−C(sp2) cleavage of alkynoates for the construction of dibenzo[c,h]xanthene derivatives is reported. A catalytic amount of triflic acid (TfOH) afforded an efficient transformation into the final product. Furthermore, a reduction process of alkynoates was observed during the formation of dibenzo[c,h]xanthene, preliminary mechanistic studies indicated that the protonation of the new‐formed methyl group in dibenzo[c,h]xanthene mainly came from water. [ABSTRACT FROM AUTHOR]