Danishefsky synthesis

O. Kwon and S. J. Danishefsky, Synthesis of asialo GMi. New insights in the application of sulfonamidoglycosylation in oligosaccharide assembly Subtle proximity effects in the stereochemical governance of glycosylation, J. Am. Chem. Soc., 120 (1998) 1588-1599. 

The two syntheses in Schemes 8.12 and 8.13 are essentially linear. They have rather different bond-sets, yet they have the same number of steps and the same number of bonds in the bond-sets (Scheme 13.33). Accordingly, the difference in the ratio between skeletal bond-forming steps and refunctionalization steps is minimal, arising solely from differences in the polycyclization cascades. Note that step (4) in the Danishefsky synthesis counts as a refunctionalization step, because the skeleton is only temporarily extended. 

Danishefsky s synthesis reaches a high level of complexity by the middle of the synthesis sequence (step (6)), whereas in the Curran synthesis high complexity is reached in the final step of the sequence. In terms of the robustness of the plan, the Danishefsky synthesis has substantial potential for variation. Curran s synthesis has two key steps, (3) and (8), on which failure or success depends. To have such a step as the last one of a synthesis is quite daring. 

Different Strategies with Aldol Reactions The Danishefsky Synthesis of Epothilone A Relying on Intramolecular Aldol Reaction... 

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