Positive cooperativity of product mimics in the asymmetric autoinduction of Diels-Alder reactions catalyzed by a VAPOL-aluminum catalyst
Positive cooperativity of product mimics in the asymmetric autoinduction of Diels-Alder reactions catalyzed by a VAPOL-aluminum catalyst
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DOI：
10.1021/ja971246f
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发表时间：
1997-10-29
影响因子：
15
通讯作者：
Wulff, WD
中科院分区：
文献类型：
--
作者：
Heller, DP;Goldberg, DR;Wulff, WD
自桥本、Komeshima和古贺报道了手性刘易斯酸催化的第一个Diels-Alder反应以来，已经过去了18年。[1]这篇报道激发了合成界对Diels-Alder反应的兴趣，关于手性刘易斯酸的不对称Diels-Alder反应的报道数量一直稳步增加。2，3我们以前曾报道过拱形联菲咯配体3（VAPOL）的制备以及VAPOL的硼和铝配合物作为不对称Diels-Alder反应催化剂的发展。4我们在此报道了由铝催化剂介导的不对称Diels-Alder反应表现出自诱导5 -7，这是由于产物与催化剂的协同相互作用产生了更具选择性的催化剂物种。某些羰基化合物可以模拟产物的自诱导效应，并超过产物可能的诱导，达到观察到几乎完美的正协同作用的程度。但是我们选择将我们的研究集中在与酯的反应上，因为与醛的反应太快而不能方便地监测超过时间此外，我们在筛选几种底物时看到的效果表明，酯的效果要大得多。该反应如表1所示进行，并进行如下反应：
It has been 18 years since Hashimoto, Komeshima, and Koga reported the first example of a Diels-Alder reaction catalyzed by a chiral Lewis acid. 1 This report served to galvanize the pre-existing interest in the Diels-Alder reaction in the synthetic community, and the number of reports on asymmetric Diels-Alder reactions with chiral Lewis acids has steadily increased until the present. 2, 3 We have previously reported the preparation of the vaulted biphenanthrol ligand 3 (VAPOL) and the developement of boron and aluminum complexes of VAPOL as catalysts for asymmetric Diels-Alder reactions. 4 We report herein that the asymmetric Diels-Alder reactions mediated by the aluminum catalyst exhibit an autoinduction5-7 which is due to a cooperative interaction of the product with the catalyst to generate a more selective catalyst species. It is also shown that certain carbonyl compounds can mimic the auto-inductive effect of the product and surpass the inductions possible with the product to the point where nearly perfect positive cooperativities are observed.An autoinduction is seen with both aldehyde and ester dienophiles, but we have chosen to focus our study on the reaction with esters since the reactions with aldehydes are too fast to conveniently monitor the asymmetric induction over time. Also, the effect that we have seen in our screening of several substrates reveals that the effect is much bigger for esters. This reaction was performed as indicated in Table 1 and was followed