History
The Mortreux system consists of the molybdenum catalyst molybdenum hexacarbonyl Mo(CO)6 and resorcinol cocatalyst. In 1975 T.J. Katz proposed a metal carbyne and a metallacyclobutadiene as an intermediate and in 1981 R.R. Schrock characterized several metallacyclobutadiene complexes that were catalytically active.
The Schrock catalyst system tris(t-butoxy)(2,2-dimethylpropylidyne)tungsten(VI) is unreactive towards alkenes. On the other hand Fischer carbenes have no value in alkyne or alkene metathesis.
The Schrock catalyst is commercially available and is prepared by amidation of tungsten tetrachloride with lithium dimethylamide to a W2(NMe2)6 which undergoes alcoholysis by tert-butoxy groups with tert-butanol.
This alkylidyne complex undergoes a metathesis with neoheptyne to give the final product. In 2001, Fürstner reported a new molybdenum catalyst replacing alkoxide with aniline ligands.
Read more about this topic: Alkyne Metathesis
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