A common approach to the total synthesis of l-arabino-, l-ribo-C _(18)-phytosphingosines, ent-2-epi-jaspine B and 3-epi-jaspine B from d-mannose

摘要

A common strategy for the total syntheses of the protected l-arabino- and l-ribo-C_(18)-phytosphingosine (8 and 9, respectively), HCl salts of ent-2-epi-jaspine B (ent-6) and 3-epi-jaspine B (7) with efficient use of both flexible building blocks 26 and 27 was achieved. The key step of this approach was [3,3]-sigmatropic rearrangement of allylic trichloroacetimidate 21 and thiocyanate 22, which were derived from the known 2,3:5,6-di-O-isopropylidene-d- mannofuranose 18 as the source of chirality. The side chain functionality was installed utilizing a Wittig reaction.