Total Synthesis of (-)-PA-48153C, a Novel Immunosuppressive 2-Pyranone Derivative

Article abstract of DOI:10.1021/jo00128a032

(-)-PA-48153C (1), an immunosuppressive agent, was synthesized by starting from (+)-methyl 4,6-O-benzylidene-α-D-glucopyranoside (2) and (S)-(+)-methyl 3-hydroxy-2-methylpropionate (3).The key steps in this synthesis relied upon trans-diaxial ring opening of epoxy mesylate 11 in order to introduce the C-5β ethyl group, Wittig reaction of aldehyde 15 with a phosphorus ylide derived from phosphonium salt 28 to combine the cyclic segment B and the acyclic segment C, and regio- and stereoselective hydroboration of (Z)-olefin 29 in order to introduce the C-8α hydroxyl group.The absolute stereochemistry of PA-48153C was unambiguously determined to be the same as that of 1.