Synthetic studies toward C-1027 chromophore: construction of a highly unsaturated macrocycle

Construction of the highly unsaturated macrolactone of C-1027 chromophore (1) was investigated. Coupling of three fragments (2, 3, 4) led to the seco-acids in a concise manner. The protecting groups on the seco-acids influenced the yield of macrolactonization, and efficient conversion from acetonide 13 to lactone 15 was achieved using the Corey–Nicolaou protocol. The desired atropisomer thus obtained was converted to triol 18a, which will serve as an important intermediate in the total synthesis of C-1027 chromophore.