Department of Chemistry, Shanghai University, 99 Shangda Road, Shanghai, 200444, P.R. China.
Chemistry. 2012 Jul 27;18(31):9645-50. doi: 10.1002/chem.201104071. Epub 2012 Jul 2.
Multicomponent cycloadditions with readily available isocyanides, allenoates, and isatylidene malononitriles are disclosed. This reaction, which does not require the aid of any catalyst, allows the efficient syntheses of spirocyclic oxindoles with excellent regioselectivity. Reactions with ethyl 2,3-butadienoate and various structurally diverse α- and γ-substituted allenoates are also fully explored. Remarkably, we have shown that the usual three-component process can be further developed into an unprecedented four-component cycloaddition in the presence of water, which provides a new strategy to access highly unusual tricyclic oxindoles. From a synthetic point of view, this protocol is very interesting considering the high level of complexity reached in one step. The mechanism is thought to proceed by a triple Michael/cyclization process by using allenoate as a three carbon atom component (3 C). Furthermore, multicomponent reaction with γ-substituted allenoate also results in a very interesting conversion. In such cases, the unusual cleavage of the "C=C" double bond of isatylidene malononitrile and one of the "C=C" double bonds of allenoate is always observed.
本文公开了一种多组分环加成反应，涉及易得的异氰酸酯、丙二烯酸酯和异亚苄基丙二腈。该反应无需任何催化剂的辅助，能够高效合成具有优异区域选择性的螺环吲哚酮。该反应还与各种结构不同的α-和γ-取代丙二烯酸酯进行了充分的探索。值得注意的是，我们已经证明，通常的三组分反应在水的存在下可以进一步发展为前所未有的四组分环加成反应，这为获得高度不寻常的三环吲哚酮提供了一种新策略。从合成的角度来看，考虑到一步达到的高复杂程度，该方案非常有趣。该机理被认为是通过三分子迈克尔加成/环化过程进行的，其中丙二烯酸酯作为三个碳原子组成部分（3C）。此外，与γ-取代丙二烯酸酯的多组分反应也会导致非常有趣的转化。在这种情况下，异亚苄基丙二腈的“C=C”双键和丙二烯酸酯的“C=C”双键之一的不寻常断裂总是会观察到。
