Silyl Cation-Initiated, Brønsted Acid-Catalyzed Strategy toward Unsymmetrical 3,3-Disubstituted 2‑Oxindoles and Azonazine Cores

Herein, a mild, metal-free, robust approach for synthesizing valuable and sterically demanding unsymmetrical 3,3-disubstituted 2-oxindoles via reductive cyclization of α-ketoamides is reported. This operationally simple protocol is initiated by a silyl cation and further catalyzed by a Brønsted acid...

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Bibliographic Details
Published in:Journal of organic chemistry 2022-08, Vol.87 (16), p.11097-11111
Main Authors: Khan, Jabir, Yadav, Naveen, Tyagi, Aparna, Hazra, Chinmoy Kumar
Format: Article
Language:English
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Summary:Herein, a mild, metal-free, robust approach for synthesizing valuable and sterically demanding unsymmetrical 3,3-disubstituted 2-oxindoles via reductive cyclization of α-ketoamides is reported. This operationally simple protocol is initiated by a silyl cation and further catalyzed by a Brønsted acid. We have utilized a wide range of arenes, amines, and thiols as coupling partners with various α-ketoamides. The products were afforded in excellent regioselectivity and good functional group tolerance. This procedure provides easy access to the scaffolds of azonazine and its derivatives with an excellent syn-diastereoselectivity bearing all-carbon quaternary stereocenters.
ISSN:0022-3263
1520-6904
DOI:10.1021/acs.joc.2c01351