SYNTHETIC STUDIES DIRECTED TOWARDS EPOTHILONE-A - ENANTIOSELECTIVE SYNTHESIS OF A C-7-C-15 CARBOXALDEHYDE SEGMENT

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