Catalytic Asymmetric Total Synthesis of Exiguolide.

: The catalytic asymmetric total synthesis of (-)-exiguolide, a complex 20-membered macrolide embedded with a bis(tetrahydropyran) motif, is  reported . The convergent synthesis involves the construction of the C1-C11 tetrahydropyran segment via catalytic asymmetric allylation and Prins cyclization, and the formation of the C12-C21 phosphonate segment via catalytic asymmetric cyclocondensation reaction and Johnson-Claisen rearrangement. The synthesis of 15- epi -exiguolide is also described.