Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... The C1C9 segment of epothilons was generated by an aldol reaction between chiral aldehyde 3 and ethyl ketone 4. Removal of the TBS protecting groups and debenzylation generated spiro ketal 13 which was analyzed by X-ray crystallography. ... Aldol reaction of key fragments ...