Synthetic studies directed toward amphidinol 2: elucidation of the relative configuration of the C1–C10 fragment

Model compounds (11 and 12) for the C1–C10 tetrahydropyran fragment of amphidinol 2 were prepared from (2S)-benzyloxypropanal in 9 steps. The synthetic route relied on diastereoselective diene-aldehyde cycloaddition, stereoselective C-allylation, and reagent based enantioselective aldehyde allylation. Comparison of the NMR spectra for models 11 and 12 with that for amphidinol 2 indicated that the C1–C10 segment of the natural product possesses the 2R∗,4R∗,6R∗,7S∗,8R∗,10S∗ relative configuration.