Divergent Total Syntheses to Azafluor­anthene and Dehydroaporphine Alkaloids

Facile divergent total syntheses for azafluoranthene and dehydroaporphine alkaloids have been successfully developed. A common intermediate, a biarylsulfonamide-protected amino aldehyde, underwent either a cascade or a stepwise cyclization to furnish a tetracyclic skeleton related to the azafluoranthene alkaloids. Natural products, triclisine and telitoxine, were prepared to illustrate the use of this approach. Subsequent C-homologation of the aldehyde moiety on the same intermediate by means of a Wittig reaction allowed the synthesis of aporphine alkaloids, as exemplified by the preparation of dehydronornuciferine. This synthetic approach could be applicable to the syntheses of other azafluoranthene-related as well as aporphine-related alkaloids.

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