The Diels-Alder adduct of furfuryl alcohol and maleic anhydride was converted into a 3,4,5-trihydroxy-9-oxo-8-oxabicyclo[4.3.0]non-1 (6)-ene-2-carboxylic derivative, then into polyhydroxylated systems containing three contiguous, oxidized, one-carbon side-chains that are potential intermediates in the synthesis of 6-epi-squalestatins and analogues. (C) 1999 Elsevier Science Ltd. All rights reserved.