Synthetic studies directed towards epothilone A:: Enantioselective synthesis of a C7-C15 carboxaldehyde segment

Enantioselective syntheses of a protected C-7-C-15 fragment of epothilone A is reported in ten manipulations in good overall yield. An alkynyl-aluminum induced opening of a chiral epoxide followed by reordering of functionality furnished the iodide 18. Chain elongation with N-propionyl-1S-(-)-2,10-camphorsultam 19 afforded the elaborated acylsultam 20 which was reduced and reoxidized to furnish a protected chiral aldehyde 6 suitable for aldol condensation, representing the C-7-C-15 portion of epothilone A. (C) 1997 Elsevier Science Ltd. All rights reserved.