Regioselective alkylation of the trifluoromethyl analog of Hagemann’s ester

The reactivity of the enolate of the 4-carbethoxy-3-trifluoromethyl-cyclohex-2-enone (1) toward electrophiles has been studied and compared with that of the parent Hagemann’s ester. Presence of the CF3 group could allow the selective introduction of substituents at three different sites. With alkyl halides the C-2 alkylation is completely favored. High selectivity is directed to the C-4 site with ethyl chloroformate, and only O-silylation occurred with a silylated chloride.