Multidentate Triphenolsilane-Based Alkyne Metathesis Catalysts

A series of triphenolsilane-coordinated molybdenum(VI) propylidyne catalysts has been developed, which are resistant to small alkyne polymerization and compatible with various functional groups (including phenol substrates). The catalysts remain active in solution for days at room temperature (months at 30 degrees C). The catalysts are also compatible with 5 angstrom molecular sieves (small alkyne scavengers), and have enabled the homodimerization of small alkyne substrates at 4070 degrees C in a closed system, with dimer products being obtained in 7696% yields. A shape-persistent aryleneethynylene macrocycle (11) was also prepared on a gram scale with 0.5mol% catalyst loading, in almost quantitative yield.