Stereoselective syntheses of (–)-goniotriol and (–)-8-acetylgoniotriol from D-glycero-D-gulo-heptono-γ-lactone

Abstract

1-O-Acetyl-2,4:5,6-di-O-isopropylidene-1-C-phenyl-D-glycero-D-ido-hexitol 6 has been converted by three consecutive reactions (selective deacetonation, glycol cleavage oxidation, and Wittig reaction) into (Z)-methyl 7-O-acetyl-4,6-O-isopropylidene-7-C-phenyl-D-ido-hept-2-enote 9 which with basic methanol gave 2-deoxy-4,6-O-isopropylidene-3-O-methyl-7-C-phenyl-D-glycero-L-ido-heptono-δ-lactone 10. The structure of 10 has been confirmed by X-ray crystallographic analysis. 1,3-Di-O-acetyl-2,4:5,6-di-O-isopropylidene-1-C-phenyl-D-glycero-D-gulo-hexitol 11 has been transformed via a sequence involving selective hydrolysis, deacetylation, glycol cleavage oxidation, and Wittig reaction into (Z)-methyl 4,6-O-isopropylidene-7-C-phenyl-L-gluco-hept-2-enonate 14 which with DBU provided (Z)-5,7-O-isopropylidene-8-C-phenyl-L-gluco-hept-3-enono-δ-lactone 16 from which (–)-goniotriol 1 and (–)-8-acetylgoniotriol 2 can be obtained readily. Absolute configurations 8-C-phenyl-L-gluco-hept-3-enono-δ-lactone 3 and 8-O-acetyl-8-C-phenyl-L-gluco-hept-3-enono-δ-lactone 4 are assigned to natural goniotriol and 8-acetylgoniotriol respectively.