Total Synthesis of Phenanthroindolizidines Using Strained Azacyclic Alkynes

We report a concise approach to phenanthroindolizidine alkaloids, wherein strained azacyclic alkynes are intercepted in Pd-catalyzed annulations. Two types of strained intermediates were evaluated: a functionalized piperidyne and a new strained intermediate, an indolizidyne. We show that each can be...

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Bibliographic Details
Published in:Organic letters 2023-07, Vol.25 (27), p.5044-5048
Main Authors: Spence, Katie A., Hoffmann, Marie, Garg, Neil K.
Format: Article
Language:English
Subjects:
Alkynes
Catalysis
Phenanthrolines
Transition Elements
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Summary:We report a concise approach to phenanthroindolizidine alkaloids, wherein strained azacyclic alkynes are intercepted in Pd-catalyzed annulations. Two types of strained intermediates were evaluated: a functionalized piperidyne and a new strained intermediate, an indolizidyne. We show that each can be employed, ultimately allowing access to three natural products: tylophorine, tylocrebine, and isotylocrebine. These efforts demonstrate the successful merger of strained azacyclic alkyne chemistry with transition-metal catalysis for the construction of complex heterocycles.
ISSN:1523-7060
1523-7052
1523-7052
DOI:10.1021/acs.orglett.3c01740