A novelapproach for the syntheses of lophocladines A and B has been developed. These compounds were prepared in 4–6 steps with moderate to excellent overall yields. The key step involved the nucleophilic substitution of 4-chloronicotinic acid with the carbanion generated from phenylacetonitrile. Subsequent reduction of the cyano group, lactamization and oxidation furnished lophocladine A in 50% yield
Preparation of Polyfunctional Naphthyridines by Cobalt-Catalyzed Cross-Couplings of Halogenated Naphthyridines with Magnesium and Zinc Organometallics
作者:Robert Greiner、Dorothée S. Ziegler、Denise Cibu、Andreas C. Jakowetz、Florian Auras、Thomas Bein、Paul Knochel
DOI:10.1021/acs.orglett.7b03242
日期:2017.12.1
CoCl2 (5%) catalyzes cross-couplings of various halogenated naphthyridines with alkyl- and arylmagnesium halides. Also, arylzinc halides undergo smooth cross-couplings with various naphthyridines in the presence of CoCl2·2LiCl (5%) and sodium formate (50%), leading to polyfunctional arylated naphthyridines. Two of these arylated naphthyridines are highly fluorescent, with quantum efficiencies reaching