The first, involving a reversible ene reaction yielded 10-deuteriocarvone with some substitution at other reactive centres, An improverent to this route involved the decomposition of an organozinc reagent of 10-chlorocarvone which gave a better yield of product substituted only at C-10, As a prelininary to a possible radioinnunoassay with the above aaterial, four derivatives of carvone linked to bovine serum albunin were prepared, Key Uords: Tritium and deuteriun-labelled carvone, synthesis, radioirrunoassay IIITRODUCTIOl'4 (-)-Carvone (1) is the principal constituent of the essential oil of Xentha spicata L. and is of widespread occurrence as a minor component in the oil of many other herbs: it is a compound of some commercial importance. We set out to synthesise labelled carvone of sufficient activity for use in a radioimmunoassay designed to select high-yielding cell clumps from tissue cultures of Xentha spicata with a view to establishing a clone of productive cells. Only reactions which substituted a tritium label in the 10-Ethyl group were investigated as this position should be inert under the conditions of radioimunoassay and is a convenient target carbon. Deuterium was used in the developmental stages.