Preparation of useful synthetic intermediates of Taxol analogs, cyclooctenone derivatives.

Stereoselective syntheses of omega-(alpha-bromoketo) octanals and nonanal with oxygenated functions and formation of the corresponding eight-membered carbocyclic aldols by subsequent samarium(II)-mediated cyclization are demonstrated. Cyclooctenones deoxygenated at the C2 or C10 position in the taxane framework are prepared by dehydration of the above aldols.