Stereospecific synthesis and absolute configuration of the (2S,3S,4S)-isomer of 2-methyl-2-(carboxycyclopropyl)glycine (MCCG)

The conformationally restricted metabotropic glutamate receptor antagonist (2S,3S,4S)-2-methyl-2-(carboxycyclopropyl)glycine 1 (MCCG) has been synthesized in a stereoselective manner (>99% ee) with the (2S,3S,4S) absolute configuration of this molecule being confirmed by X-ray crystallographic analysis. Subsequent physico–chemical studies were undertaken and the data are at odds with those of the commercially available product.