Urea Activation by an External Brønsted Acid: Breaking Self-Association and Tuning Catalytic Performance

Isaac Sonsona, Eugenia Marqués-López, Marleen Häring, David Díaz, Raquel Herrera
2018 Catalysts  
In this work, we hypothesize that Brønsted acids can activate urea-based catalysts by diminishing its self-assembly tendency. As a proof of concept, we used the asymmetric Friedel–Crafts alkylation of indoles with nitroalkenes as a benchmark reaction. The resulting 3-substituted indole derivatives were obtained with better results due to cooperative effects of the chiral urea and a Brønsted acid additive. Such synergy has been rationalized in terms of disassembly of the supramolecular catalyst
more » ... ggregates, affording a more acidic and rigid catalytic complex.
doi:10.3390/catal8080305 fatcat:3nafxbfdufc3liisrvrsnx73aa