3.4- diamino-3-cyclobutene-l,2-dione

Figure 11.11. 3,4-Diamino-3-cyclobutene-l,2-diones redrawn from Ref. 34.

Many NMDA receptor antagonists have been synthesized that are based on the structure of glutamate, NMDA, and AMPA. Several 3,4-diamino-3-cyclobutene-l,2-dione derivatives (34) have been synthesized and found to be good inhibitors of the NMDA receptor (Fig. 

Kinney, W. A., Lee, N. E., Garrison, D. T, Podlesny, E. J., Jr, Simmonds, J. T, Bramlet, D., Notvest, R. R., Kowal, D. M., Tasse, R. P. Bioisosteric replacement of the a-amino carboxylic functionality in 2-amino-5-phosphonopentanoic acid yields unique 3,4-diamino-3-cyclobutene-l,2-dione containing NMDA antagonists. J. Med. Chem. 1992, 35, 4720-4726. 

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