Ethyl acetoacetate, when heated alone ( uncatalyzed ) with benzyl alcohol, forms synthetically useful benzyl acetoacetate ( benzyl groups being easily removed later by catalytic hydrogenolysis over Pd / C under neutral conditions ), via a mechanism involving acetylketene.
22.
Yields were significantly improved, by the use of preformed diethyl aminomalonate ( prepared by the hydrogenolysis of diethyl oximinomalonate in ethanol, over Pd / C ), and adding a mixture of diethyl aminomalonate and the beta-diketone to actively boiling glacial acetic acid.
23.
TFE can also be prepared by hydrogenolysis of compounds of generic formula CF 3 " CHOH " OR ( where R is hydrogen or an alkyl group containing from one to eight carbon atoms ), in the presence of a palladium containing catalyst deposited on activated charcoal.
24.
In the example shown, the protected amino acid tyrosine, the benzyl ester can be removed by hydrogenolysis, the fluorenylmethylenoxy group ( Fmoc ) by bases ( such as piperidine ), and the phenolic tert-butyl ether cleaved with acids ( e . g . with trifluoroacetic acid ).
