Retrosynthesis
As illustrated in Retrosynthetic Scheme I, Taxol was derived from diol 7.2 by an ester bond formation, according to the Ojima-Holton method. This diol comes from carbonate 6.3 by the addition of phenyllithium. The oxetane ring in compound 6.3 was obtained via an SN2 reaction involving a mesylate derived from acetate 4.9. Ring B was closed via a McMurry reaction involving dialdehyde 4.8 which ultimately was derived from aldehyde 4.2 and hydrazone 3.6 using a Shapiro coupling reaction.
| Retrosynthesis Scheme 1 |
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Retrosynthetic Scheme II indicates that both the aldehyde and the hydrazone used in the Shapiro coupling reaction were synthesized using Diels-Alder reactions.
| Retrosynthesis Scheme 2 |
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Read more about this topic: Nicolaou Taxol Total Synthesis