WILKINSON Carbonylation decarbonylation catalyst

WILKINSON Carbonylation decarbonylation catalyst Rh catalyst for carbonylation, decarbonylation, oxygenation, benzyl cleavage... 

Rhodium is used in a variety of catalysts. In particular, the Wilkinson complex RhCl(PPhv)3 as a rhodium catalyst is well known, and hydrogenations, hydro-metalations, carbonylations, decarbonylations, isomerizations and cyclizations proceed selectively [34,63]. 

Methyl deoxypodocarpate 127 (Scheme 1) 129) represents a simple problem since the ketone 132 is well-known and readily available from Hagemann s ester in three steps. The problem of geminal alkylation of this ketone stems from its existence as an EjZ mixture of ring fusion isomers. Recognizing that decarbonylation of aldehydes occurs readily with Wilkinson s catalyst creates a structural equivalence of an acetaldehyde chain and a methyl group as in 128. This simple relationship immediately establishes several options, a simple one uses a thioacetal such as 129 as a synthon for the aldehyde. The presence of a carbonyl group three carbons away... 

Wilkinson s catalyst is useful for effecting intramolecular decarbonylation of aldehydes to hydrocarbons with retention of configuration (Walborsky and Allen, 1971). Decarbonylation of disubstituted cyclopropenones by iron, nickel, or cobalt carbonyls results in the formation of alkynes (Bird and Hudec, 1959). Tetraphenylethylene was obtained in 68% yield by reaction of diphenylketene with cobalt carbonyl (Hong et ai, 1968). 

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