Dianions of glyoxylic acid thioketals: conventent α-keto acid equivalents

Abstract

By varying the solvent, reaction temperature, and bases (i.e., gegenions present), optimum conditions for the alkylation of the dianions of glyoxylic acid derivatives 8 and 9 were established. It was found that the easily prepared, thermally stable, tetrahydrofuran-soluble potassium dianion of bis(ethylthio)acetic acid was readily alkylated by alkyl halides, tosylates, epoxides, and N-tosyl aziridines. The latter alkylation is being used to develop a possible cytochalasin synthesis.The alkylated products may be readily converted into the corresponding α-keto acids or methyl 2,2-bismethoxycarboxylates.