Reactions of Sulfonylphthalide with Diverse Activated Imines for the Synthesis of Enaminophthalides, Spiro-isoquinolinones, and Homalicine Natural Products

The reactivity of the Hauser–Kraus (H–K) donor, 3-sulfonylphthalide, with various activated imines under basic conditions is demonstrated. The reaction of 3-sulfonylphthalide with Boc-protected aldimine provides a rapid access to 1,2-imine adducts and alkylidenephthalides depending upon the stoichio...

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Bibliographic Details
Published in:Journal of organic chemistry 2023-04, Vol.88 (7), p.4038-4051
Main Authors: Basu, Pallabita, Satam, Nishikant, Pati, Soumyaranjan, Suresh, Alati, Namboothiri, Irishi N. N.
Format: Article
Language:English
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Summary:The reactivity of the Hauser–Kraus (H–K) donor, 3-sulfonylphthalide, with various activated imines under basic conditions is demonstrated. The reaction of 3-sulfonylphthalide with Boc-protected aldimine provides a rapid access to 1,2-imine adducts and alkylidenephthalides depending upon the stoichiometry of the base. The alkylidenephthalides could be transformed to ketophthalides, a new class of phthalides, on acid hydrolysis, which upon reductive cyclization using Zn/AcOH afforded the natural product homalicine. On the contrary, the Boc-protected isatinimines undergo an efficient H–K annulation to provide spiro-isoquinolinone-oxindoles in excellent yields. However, the corresponding conjugated ketimines afforded Michael adducts, which were converted to the corresponding alkylidenephthalides under TBAF conditions.
ISSN:0022-3263
1520-6904
DOI:10.1021/acs.joc.2c00816