Synthetic studies of the ionophore antibiotic zincophorin. 2. Iterative sigmatropic construction of the C1–C11 subunit

Advanced intermediates 22 and 23, representing the C1–C11 subunit of the ionophore zincophorin, have been prepared by a scheme incorporating sequential glycolate Claisen and [2,3] Wittig rearrangements to establish the key structural and stereochemical elements of the title compound.