Total Synthesis of (+)-Zaragozic Acid C

A total synthesis of (+)-zaragozic acid C is described. Key features of the synthesis are the use of a double Sharpless asymmetric dihydroxylation reaction of diene 6 to control stereochemistry at four contiguous stereocenters from C3 to C6; the introduction of the C1-side chain by reaction between the anion derived from the dithiane monosulfoxide 27 and the core aldehyde 12; a high yielding, acid-mediated simultaneous acetonide deprotection−dithiane removal−ketalization procedure leading exclusively to the 2,8-dioxabicyclo[3.2.1]octane core 34; and a novel triple oxidation procedure allowing installation of the tricarboxylic acid.