Synthesis via N-acyliminium cyclisations of N-heterocyclic ring systems related to alkaloids
نویسندگان
چکیده
منابع مشابه
Diverse N-Heterocyclic Ring Systems via Aza-Heck Cyclizations of N-(Pentafluorobenzoyloxy)sulfonamides.
Aza-Heck cyclizations initiated by oxidative addition of Pd(0) -catalysts into the N-O bond of N-(pentafluoro-benzoyloxy)sulfonamides are described. These studies, which encompass only the second class of aza-Heck reaction developed to date, provide direct access to diverse N-heterocyclic ring systems.
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The first total synthesis of the oxindole alkaloid gelsedine (1) starting from (S)-malic acid is described. The key step is a novel iodide-promoted intramolecular reaction of an allene with an N-acyliminium ion intermediate which provided in a single step the bicyclic vinyl iodide 11. Other important steps are the highly stereoselective Pd-catalyzed Heck cyclization of N-methylanilide 23a which...
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Syntheses of thiazolidine-fused heterocycles via exo-mode cyclizations of vinylogous N-acyliminium ions incorporating heteroatom-based nucleophiles have been examined and discussed. The formation of (5,6)-membered systems was feasible with all nucleophiles tried (O, S and N), while the closing of the five-membered ring was restricted to O- and S-nucleophiles. The closure of a four-membered ring...
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A facile, moderate to high yielding synthesis of hexahydro-(di)-benzazocinones is described via an intramolecular N-acyliminium ion cyclisation. The iminium ion intermediates are formed from the readily available 4,4-diethoxybutyl amides with an excess of triflic acid. For electron-withdrawing substituents, better yields were obtained from the pre-formed 2-hydroxypyrrolidine amides. From NMR st...
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ژورنال
عنوان ژورنال: Arkivoc
سال: 2001
ISSN: 1551-7012
DOI: 10.3998/ark.5550190.0002.101