Our recent work has proved the viability of the de Mayo strategy for the construction of the basic Taxane skeleton. We have also developed a sequence of reactions which will convert an allylic alcohol into the oxetane/tertiary acetate grouping of Baccatin III (Taxol, Cephalomannine). We now wish to extend and amplify our model studies to the actual synthesis of a Baccatin III. Our approach is to construct the central (B) ring by a photocycloaddition-Grob fragmentation sequence applied to two highly functionalized synthons which are to be coupled using an oxazolinone as a scaffold. The consequences of this approach are the introduction of l) the C-l tertiary hydroxyl group; 2) the exo-C-8 angular methyl group; 3) a double bond at C-9,l0, which serves as the precursor to the oxygen functions at these positions in Baccatin III; 4) a functionalized carbon at C-4, which will serve as the starting point for construction of the oxetane/tertiary acetate grouping; and 5) all other methyl groups and (latent) oxygen funtions of Baccatin III.
