An efficient, highly convergent, stereocontrolled total synthesis of the potent antimitotic agent (+)-discodermolide (1) has been achieved on gram scale. Key elements of the successful strategy include (1) elaboration of three advanced fragments from a common precursor (CP) which embodies the repeating stereochemical triad of the discodermolide backbone, (2) σ-bond installation of the Z trisubstituted olefin, exploiting a modified Negishi cross-coupling reaction, (3) synthesis of a late-stage phosphonium salt utilizing high pressure, and (4) Wittig installation of the Z disubstituted olefin and the terminal (Z)-diene.

The availability of (+)-discodermolide and the analogs, and the resultant SAR analysis, have permitted an exploration of the similarities and differences between (+)-discodermolide and Taxol. Docking of the X-ray/solution structure of (+)-discodermolide into the Taxol binding site of beta-tubulin revealed two possible binding modes (models I and II). The preferred pharmacophore model (I), in which the C19 side chain of (+)-discodermolide matches with the C2 benzoyl group of Taxol and the delta-lactone ring of (+)-discodermolide overlays with the C13 side chain of Taxol, concurred with the results of the SAR analysis.

A convenient, general, and high yielding Pd-catalyzed cross-coupling of methanesulfonamide with aryl bromides and chlorides is reported. The use of this method eliminates concern over genotoxic impurities that can arise when an aniline is reacted with methanesulfonyl chloride. The application of this method to the synthesis of dofetilide is also reported.

[formula: see text] A triply convergent, highly efficient second-generation synthesis of the potent antimitotic agent (+)-discodermolide (1) has been achieved on a 1-g scale.