the carbocation as a highly powerful Lewis acid catalyst for organic reactions. The stable and easily available triphenylmethyl (trityl) cation was found to be a highly efficient catalyst for the Diels–Alder reaction for a range of substrates. Catalyst loadings as low as 500 ppm, excellent yields, and good endo/exo selectivities were achieved. Furthermore, by changing the electronic properties of the
通常,
路易斯酸催化剂是基于
金属的化合物,由于它们对低位的空轨道具有反应性。然而,碳阳离子是一种潜在的
路易斯酸,已被忽略不计,它是一种催化剂。我们已经证明了碳正离子化作为有机反应的强力
路易斯酸催化剂的潜力。稳定且容易获得的三苯甲基(三苯甲基)阳离子被发现是用于多种底物的Diels-Alder反应的高效催化剂。催化剂负载量低至500 ppm,优异的收率和良好的内/外达到了选择性。此外,通过改变三苯乙
铵离子上取代基的电子性质,可以调节催化剂的
路易斯酸度以控制反应的结果。该碳阳离子作为
路易斯酸催化剂的能力也进一步扩展到迈克尔反应。