Purines, pyrimidines, and imidazoles. XXVII. The synthesis of some derivatives and analogues of N-(5-amino-1-beta-D-ribofuranosylimidazole-4-carbonyl)-L-aspartic acid 5'-phosphate (SAICAR) including a competitive enzyme (adenylosuccinate AMP-lyase no. 4.3.2.2.) inhibitor-N-(5-amino-1-beta-D-ribofuranosylimidazole-4-carbonyl)-L-threo-beta-methyl aspartic acid 5'-phosphate. - Burrows IE; Shaw G; Wilson DV (Journal of the Chemical Society. Perkin transactions 1, 1968)