Studies toward the Synthesis of Iriomoteolide-2a: Construction of the C(6)–C(28) Fragment

The synthesis of an appropriately functionalized advanced C(6–28) fragment (3) of the marine macrolide iriomoteolide-2a (1) has been achieved in a highly efficient manner. The C(6)–C(18) fragment of 1 is prepared via a radical cyclization of a vinyl ether intermediate and palladium-promoted hydrostannylation/iodination. Paterson aldol reaction and Peterson olefination are used to construct the C(19)–C(28) fragment. The union of the C(6)–C(18) and C(19)–C(28) fragments is accomplished via a Suzuki–Miyaura coupling reaction.