Total Synthesis of (+)-SCH 351448

A convergent synthesis of (+)-SCH 351448 (1), a monosodium salt of a C-2-symmetric macrodiolide, is described. Our approach is based on a [4 + 2] annulation with a chiral allyl silane (anti-5c) to assemble the pyran subunits. Homodimerization was carried out in a stepwise fashion; initial esterification at C29' followed by macrocyclization at C29 afforded the desired macrodiolide.