D-ribo-2-Benzamido-1,3,4-trihydroxyoctadecane (N-benzoyl-C18-phytosphingosine) and D-ribo-2-benzamido-1,3,4-trihydroxyeicosane (N-benzoyl-C20-phytosphingosine) have been synthesised by Wittig reactions between the aldehyde (IX) derived from 2-amino-2-deoxy-D-glucose and the appropriate long-chain phosphoranes. The properties of the derivatives of the synthetic C18-phytosphingosine are identical with those of the corresponding derivatives of the natural base, thus confirming the structure established by previous degradative studies.