Organocatalytic Applications of Sulfonyl Squaramides in Anion-Recognition Strategies

A modular, 3-steps protocol for the synthesis of N-sulfonyl squaramides has been developed. The strategic installation of a tetrahedral, electron-withdrawing sulfonyl group into the squaramido core allowed the prevention of undesired self-aggregations, therefore upgrading the solubility in common or...

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Bibliographic Details
Authors: Benítez, Manuel, Matador, Esteban, Velázquez, Marta, Lassaletta, José M, Fernández, Rosario, Monge, David
Format: article
Status:Published version
Publication Date:2024
Country:España
Institution:Consejo Superior de Investigaciones Científicas (CSIC)
Repository:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/381573
Online Access:http://hdl.handle.net/10261/381573
https://api.elsevier.com/content/abstract/scopus_id/85208953098
Access Level:Open access
Keyword:Alkylation
Anion-binding catalysis
Anion-recognition
Dearomatization
Sulfonyl squaramides
Description
Summary:A modular, 3-steps protocol for the synthesis of N-sulfonyl squaramides has been developed. The strategic installation of a tetrahedral, electron-withdrawing sulfonyl group into the squaramido core allowed the prevention of undesired self-aggregations, therefore upgrading the solubility in common organic solvents, and moreover, enhancing their H-bond donor abilities for molecular recognition. These unique features have been efficiently exploited in two different ion-pairing reactions: (i) the challenging C4-selective dearomatization of 2-picoline with silyl ketene acetals and (ii) the tritylation of N-methylindole. Furthermore, their catalytic activities have been directly compared with other common and well-established (thio)urea analogues and related H-bond donors, revealing that highly acidic designs are essential to reach optimal catalytic performances.