We were successful in optimizing the synthesis of the homoallylic alcohol 6 from hecogenine acetate 2 as an important precursor for our approach to cephalostatin analogues by doubling the yields. On this way we discovered that formation of homoallylic alcohol 6 proceeds via a diastereoselective intramolecular Lewis acid catalysed ene reaction directly from lumihecogenine acetate 3. Finally we were able to elucidate the structure of the already described but not clearly identified oxa-dimer 7.
We were successful in optimizing the synthesis of the homoallylic alcohol 6 from hecogenine acetate 2 as an important precursor for our approach to cephalostatin analogues by doubling the yields. On this way we discovered that formation of homoallylic alcohol 6 proceeds via a diastereoselective intramolecular Lewis acid catalysed ene reaction directly from lumihecogenine acetate 3. Finally we were able to elucidate the structure of the already described but not clearly identified oxa-dimer 7.