A total synthesis of (±)-ethyl acorate {(±)-ethyl (3RS)-3-[(1SR,4SR)-1-isobutyryl-4-methyl-3-oxocyclohexyl]butyrate} and (±)-epiacoric acid. An application of the generation and alkylation of a specific enolate

Abstract

After the failure of appropriate conjugate additions to the model ketone methyl 3-(3-oxocyclohex-1-enyl)butyrate (5a), a mixture of (±)-ethyl acorate (1; R = Et)(see title) and (±)-ethyl epiacorate (20)(the 3-epimer) was obtained by manipulation of the addition product (13b) of a cis–trans mixture of but-2-enonitrile and the enolate anion generated by lithium–ammonia reduction of 1-isobutyryl-4-methylcyclohex-3-enyl acetate (12). Similar reductions of α-acetoxy-ketones may represent another general method for the production of specific enolate salts.