Catalysis of a Diels-Alder reaction by amidinium ions

被引:72
作者
Schuster, T [1 ]
Kurz, M [1 ]
Göbel, MW [1 ]
机构
[1] Univ Frankfurt, Inst Organ Chem, D-60439 Frankfurt, Germany
关键词
D O I
10.1021/jo991372x
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
Amidines and guanidines are important functional groups in molecular recognition and host-guest chemistry. Here it is shown that lipophilic amidinium ions catalyze a cycloaddition reaction representing the key step of the Quinkert-Dane estrone synthesis. Hydrogen-bond-mediated association with the organic cation leads to an electrophilic activation of the dienophile and to enhanced rates of the Diels-Alder reaction. The observed effects are similar to those expected from mild Lewis acids. In competition experiments, amidinium catalysis favors the reaction of the less electron deficient dienophile.
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页码:1697 / 1701
页数:5
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