The preparation and characterisation of some derivatives of alpha-hydroxy-delta-lactones, in which the delta-carbon substituent on the lactone ring is trans to an adjacent isopropylidene protected diol, are described; the X-ray crystal structures of 3,4-O-isopropylidene-D-altrono-1,5-lactone and of 3,4:6,7-di-O-isopropylidene-D-glycero-D-altro-heptono-1,5-lactone are reported.