[[(2-Amino-3,4-dioxo-1-cyclo-buten-1-yl)amino]alkyl]-acid derivatives.

摘要

The invention concerns processes for preparing compounds of the formula <CHEM> in which R<1> is hydrogen, alkyl of 1 to 6 carbon atoms or phenylalkyl of 7 to 12 carbon atoms; R<2> is hydrogen, alkyl of 1 to 6 carbon atoms, alkenyl of 2 to 6 carbon atoms or phenylalkyl of 7 to 12 carbon atoms; or R<1> and R<2> taken together are Z where Z is -CH2CH2-, -CH2C(R<6>)(R<7>)CH2- or -CH2C(R<8>)(R<9>)-C(R<1><0>)(R<1><1>)CH2-, where R<6>, R<8> and R<1><0> are, independently, hydrogen, alkyl of 1 to 6 carbon atoms or hydroxyl and R<7>, R<9> and R<1><1> are, independently, hydrogen or alkyl of 1 to 6 carbon atoms, A is alkylene of 1 to 6 carbon atoms or alkenylene of 2 to 6 carbon atoms; X is CO2R<3> in which R<3> is hydrogen or alkyl of 1 to 6 carbon atoms, P(O)(OR<4>)(OR<5>) in which R<4> and R<5> are, independently, hydrogen or alkyl of 1 to carbon atoms, 3,5-dioxo-1,2,4-oxadiazolidin-2-yl or 5-tetrazolyl; or a pharmaceutically acceptable salt thereof which compounds ar NMDA antagonists useful as anticonvulsant and neuroprotectants in situations involving excessive release of excitatory amino acids.