The potent neuroexcitatory activity of kainoid amino acids in the mammalian CNS places new analogues in high demand as tools ibr neuropharmacological research. A range of 4-arylsulfanyl-substituted kainoids has been synthesised in a parallel Fashion via mesylate displacement by a number of aromatic and heteroaromatic thiolates upon (2S,3S,4R)-1-benzoyl-3-tert-butoxycarboxylmethy-4-methanesulfonyloxy pyrrolidine-2-carboxylic acid methyl ester 8, which is obtainable in eight steps from trans-4-hydroxy-L-proline 5. (C) 2000 Elsevier Science Ltd. All rights reserved.