Note on the Determination of the Absolute Configuration of (+)-2-Hydroxy-2,3-dimethylbutyric Acid

Article abstract of DOI:10.1002/hlca.19810640315

Chemical correlation of the title compound 1 with (S)-3-isopropyl-3-methyl-5-trimethylsilyl-4-penten-2-one (2) showed (+)-1 to have (S)-configuration.Key step was the Baeyer-Villiger oxidation of a very hindered, optically active methyl keton to the corresponding acetoxy compound with trifluoroperacetic acid using slightly modified buffer conditions.It is found, that the erythro/threo assignment of an α,α-disubstituted β-hydroxyester intermediate can be based on the observation, that the 1H-NMR signal of H-C(β) of the erythro isomer appears at lower field than that of the threo isomer.