Asymmetric synthesis of both enantiomers of α-methyl-α-methoxyphenylacetic acid from L-(+)-tartaric acid: formal enantioselective synthesis of insect pheromone (-)-frontalin

Both antipodes of α-methyl-α-methoxyarylacetic acid derivatives were prepared from a common chiralpool precursor L-(+)-tartaric acid. The key step involves the addition of Grignard reagents to 1,4-diketones derived from tartaric acid. The utility of this strategy was applied in the formal enantioselective synthesis of pine beetle pheromone (−)-frontalin