Biswas S, Van Steijvoort BF, Waeterschoot M, Bheemireddy NR, Evano G, Maes BUW. Expedient Synthesis of Bridged Bicyclic Nitrogen Scaffolds via Orthogonal Tandem Catalysis.
Angew Chem Int Ed Engl 2021;
60:21988-21996. [PMID:
34143924 DOI:
10.1002/anie.202106716]
[Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Indexed: 11/05/2022]
Abstract
Bridged nitrogen bicyclic skeletons have been accessed via unprecedented site- and diastereoselective orthogonal tandem catalysis from readily accessible reactants in a step economic manner. Directed Pd-catalyzed γ-C(sp3 )-H olefination of aminocyclohexane with gem-dibromoalkenes, followed by a consecutive intramolecular Cu-catalyzed amidation of the 1-bromo-1-alkenylated product delivers the interesting normorphan skeleton. The tandem protocol can be applied on substituted aminocyclohexanes and aminoheterocycles, easily providing access to the corresponding substituted, aza- and oxa-analogues. The Cu catalyst of the Ullmann-Goldberg reaction additionally avoids off-cycle Pd catalyst scavenging by alkenylated reaction product. The picolinamide directing group stabilizes the enamine of the 7-alkylidenenormorphan, allowing further product post functionalizations. Without Cu catalyst, regio- and diastereoselective Pd-catalyzed γ-C(sp3 )-H olefination is achieved.
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