Highly enantiomerically pure. (S)-(-) 2 and (R )-(+)-frontalin 3 and (-) -malyngolide. 4 were synthesized from the common chiral building block, ( 2 R ) -1, 2-O-isopropylidene-2-hydroxymethyl-pent-4-ene.-1, 2-diol 9 readily prepared in five. steps and 35% overall yield from α-D-isosaccharino-1 ,4-lactone 1 .