One-Pot Conversion of Aldehydes and Aryl Halides to Disubstituted Alkynes via Tandem Seyferth–Gilbert Homologation/Copper-Free Sonogashira Coupling

A practically convenient protocol has been developed to convert a mixture of an aldehyde, aryl halide, and the Bestmann–Ohira reagent into disubstituted acetylene via a successive addition of base (Cs2CO3) and a Pd(II) catalyst, allowing sufficient time after addition of each of these reagents for the tandem processes (Seyferth–Gilbert homologation and Sonogashira coupling) to occur. Notably, for the latter reaction, no copper catalyst was required.