A five step solid phase synthesis of 2-unsubstituted 1,2,5-thiadiazolidin-3-one 1,1-dioxides (sulfahydantoins) from N-alpha-FMOC-amino acids and aromatic aldehydes is described. The key step is the base mediated cyclitive cleavage of a resin bound N-alpha-(aminosulfonyl)-N-alpha-benzyl-amino acid to afford the desired product. This synthesis allows the preparation of a diverse library of compounds based on this heterocycle. (C) 2000 Elsevier Science Ltd. All rights reserved.