Biologically active glycosides from asteroidea, XXVI. Stereochemistry of the four diastereomers of ceramide and ceramide lactoside

The diastereomeric ceramides, (2S,3S,4R)‐, (2S,3S,4S)‐, (2S,3R,4S)‐, and (2S,3R,4R)‐2‐[(2R)‐2‐hydroxytetracosanoylamino]‐1,3,4‐hexadecanetriols 5–8 and the corresponding ceramide lactosides 1–4 have been synthesized. Compound 1 is almost identical with the natural specimen, acanthalactoside A. The physical data of these diastereomeric compounds are most useful to determine the stereochemistry of ceramides and ceramide lactosides, either isolated from natural sources or obtained by partial hydrolysis of gangliosides.