Menthyl esterification allows chiral resolution for the synthesis of artificial glutamate analogs.

Herein, we report the enantiospecific synthesis of two artificial glutamate analogs designed based on IKM-159, an antagonist selective to the AMPA-type ionotropic glutamate receptor. The synthesis features the chiral resolution of the carboxylic acid intermediate by the esterification with ʟ-menthol, followed by a configurational analysis by NMR, conformational calculation, and X-ray crystallography. A mice in vivo assay showed that (2R)-MC-27, with a six-membered oxacycle, is neuroactive, whereas the (2S)-counterpart is inactive. It was also found that TKM-38, with an eight-membered azacycle, is neuronally inactive, showing that the activity is controlled by the ring C.

Total synthesis of viridiofungin A.

Viridiofungin A, a member of amino alkyl citrate antibiotics from Trichoderma viride, was enantioselectively synthesized in naturally occurring form for the first time, employing regio- and stereoselective opening of the chiral glycidate with vinylmagnesium bromide and alkene cross metathesis of the citric acid core and hexadec-15-en-8-one as key steps.