Synthesis of 2,6-dimethyl-4-m-methylphenyl-3-cyclohexenecarboxylic acid

CHED 473

Holly J. Stein and Songwen Xie, soxie@iuk.edu. Department of Natural, Information, and Mathematical Sciences, Indiana University Kokomo, 2300 S Washington St., Kokomo, IN 46904
The compound 2,6-dimethyl-4-m-methylphenyl-3-cyclohexenecarboxylic acid was made through a five-step synthesis. Acetaldehyde and ethyl acetoacetate were condensed by the Knoevenagel reaction in the presence of piperidine. It gave a bis ester, which was cyclized, hydrolyzed and decarboxylated to ethyl 2,6-dimethyl-4-oxo-2-cyclohexenecarboxylate (1). (1) was catalytically hydrogenated over platinum catalyst in alcohol to give ethyl 2,6-dimethyl-4-oxo-cyclohexanecarboxylate (2). Basic hydrolysis of (2) with KOH/EtOH/H2O afforded 2,6-dimethyl-4-oxocyclohexanecarboxylic acid (3). Grignard reaction of (3) with m-bromotoluene provided the title compound after dehydration. The final product will be characterized by X-ray single crystal analysis. We want to use the X-ray structure to study the interaction of the two enantiomers in the solid state.