Preparation of cis- and trans-cyclodec-2- and -3-enones and studies of interconversions between them

Abstract

The cis- and trans-cyclodec-2- and -3-enones have been synthesised by stereospecific routes; a preparation of 3-hydroxycyclodecanone has also been developed. Under conditions of acid catalysis cis- and trans-cyclodec-2-enones are rapidly interconverted to give an equilibrium mixture containing 96% of the cis- and 4% of the trans-isomer. Efficient equilibration with the unconjugated isomers was not achieved. Deuteriation of the unsaturated ketones has given information on their relative ease of enolisation and the position of protonation (deuteriation) of the respective enols. The acid-catalysed isomerisation of trans- to cis-cyclodec-2-en-1-ol has been studied by use of [1-²H]-labelled substrates.