salts all compounds of the invention have an acidic group and are capable of forming base salts with various pharmaceutically acceptable cations examples of such salts include the alkali metal or alkaline earth metal salts and particularly the sodium and potassium salts these salts are all prepared by conventional techniques the chemical bases which are used as reagents to prepare the pharmaceutically acceptable base salts of this invention are those which form non toxic base salts with the herein described acidic derivatives these particular non toxic base salts include those derived form such pharmaceutically acceptable cations as sodium potassium calcium and magnesium etc these salts can easily be prepared by treating the aforementioned acidic compounds with an aqueous solution containing the desired pharmaceutically acceptable cation and then evaporating the resulting solution to dryness preferably under reduced pressure alternatively they may also be prepared by mixing lower alkanoic solutions of the acidic compounds and the desired alkali metal alkoxide together and then evaporating the resulting solution to dryness in the same manner as before in either case stoichiometric quantities of reagents are preferably employed in order to ensure completeness of reaction and maximum production of yields of the desired final product the compounds of the present invention exhibit significant glycine transport inhibiting activity and therefore are of value in the treatment of a wide variety of clinical conditions that are characterized by the deficit of glutamateric neurotransmission in mammalian subjects especially humans such conditions include the positive and negative symptoms of schizophrenia and other psychoses and cognitive deficits the compounds of the formula i of this invention can be administered via either the oral parenteral such as subcutaneous intraveneous intramuscular intrasternal and infusion techniques rectal intranasal or topical routes to mammals in general these compounds are most desirably administered.