Issue 10, 2023

Catalytic asymmetric [4 + 1] cycloaddition to synthesize chiral pyrazoline-spirooxindoles

Abstract

An asymmetric formal [4 + 1] cycloaddition of N-unprotected oxindole 3-pyridinium salts and α-halo hydrazones to access chiral pyrazoline-spirooxindoles is realized by using a chiral N,N′-dioxide-Pr(OTf)3 complex as a catalyst. The process includes base-promoted in situ formation of oxindole 3-pyridinium ylides and azoalkenes, followed by an asymmetric [4 + 1] annulation. The efficient enantiocontrol benefits from low temperature, which weakens the strong background reaction, and hydrogen bonding between the oxindole scaffold in the substrate and H2O in the catalyst, which prevents the plane flip of the oxindole ring. A range of bioactive chiral pyrazoline-spirooxindole derivatives are obtained in good yields with excellent ee values.

Graphical abstract: Catalytic asymmetric [4 + 1] cycloaddition to synthesize chiral pyrazoline-spirooxindoles

Supplementary files

Article information

Article type
Research Article
Submitted
02 mar 2023
Accepted
09 apr 2023
First published
14 apr 2023

Org. Chem. Front., 2023,10, 2422-2428

Catalytic asymmetric [4 + 1] cycloaddition to synthesize chiral pyrazoline-spirooxindoles

K. Hu, D. Zhang, S. Wang, L. Lin and X. Feng, Org. Chem. Front., 2023, 10, 2422 DOI: 10.1039/D3QO00320E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements