Catalysis of a Diels−Alder Reaction by Amidinium Ions
作者:Tilmann Schuster、Markus Kurz、Michael W. Göbel
DOI:10.1021/jo991372x
日期:2000.3.1
lipophilic amidinium ions catalyze a cycloaddition reaction representing the keystep of the Quinkert-Daneestronesynthesis. Hydrogen-bond-mediated association with the organic cation leads to an electrophilic activation of the dienophile and to enhanced rates of the Diels-Alderreaction. The observed effects are similar to those expected from mild Lewis acids. In competition experiments, amidinium catalysis