Stereoselective synthesis of (S )-MPPG, (S)-MTPG and (S )-(+)-αM4CPG from (R)-4-hydroxyphenylglycine

Abstract

(R)-4-Hydroxyphenylglycine was protected with a benzyl group and a methyl group was introduced at the α position by using the self-regeneration-of-stereocentre method. After the 4-hydroxy group had been converted into the corresponding trifluoromethanesulfonate (triflate), three palladium-catalyzed reactions were employed to furnish (S )-α-methyl-4-phosphonophenylglycine [(S )-MPPG], (S )-α-methyl-4-(tetrazol-5-yl)phenylglycine [(S )-MTPG] and (S )-4-carboxyphenyl-α-methylglycine [(S )-αM4CPG], a class of new and selective antagonists of metabotropic glutamate receptors.

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