2-Aminobenzaldehydes as versatile substrates for rhodium-catalyzed alkyne hydroacylation: application to dihydroquinolone synthesis.
2-Aminobenzaldehydes as versatile substrates for rhodium-catalyzed alkyne hydroacylation: application to dihydroquinolone synthesis.
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DOI：
10.1002/anie.201308127
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发表时间：
2013-12-09
影响因子：
16.6
通讯作者：
Willis, Michael C.
中科院分区：
文献类型：
--
作者：
Castaing, Matthias;Wason, Sacha L.;Estepa, Beatriz;Hooper, Joel F.;Willis, Michael C.
烯烃和炔烃加氢酰化反应是简单加成过程的典型实例，其显示出优异的原子经济性。[1]两种反应都导致形成新的C2 H2 C键，并提供合成有用的含羰基产物。[2]近年来，人们对将这些过程转化为合成有用的转化产生了相当大的兴趣。过渡金属催化的变体代表最大类别的加氢酰化反应，并且在这些反应中，涉及某种形式的螯合控制的过程占主导地位。使用螯合底物的需要源于以下事实：大多数金属催化的实施例通过固有不稳定的酰基金属中间体1（方案1）进行，其可导致通过脱羰基形成不需要的副产物。螯合控制策略的限制在于存在以稳定金属-酰基中间体2的配位基团也将存在于产物中。如果在最终产品中不需要该基团，则必须将其去除或转化为替代官能团。[3]尽管有这种限制，这种螯合控制方法的优点，如温和的反应条件，对映体和区域选择性的控制，[4，5]和广泛的底物范围，导致这种方法的广泛应用。克服螯合控制方法的先天限制的一种策略是开发不需要这种配位基团的催化方法;尽管这种方法有显著的成功例子，[2c，6]关于底物范围和对映体和区域选择性的显著限制仍然存在。另一种策略是将螯合单元的需要视为一种机会，并扩大有效配位基团的范围，以便各种有用的官能团可以充当关键的螯合基序。由于合成化学通常涉及官能化分子的制备，因此耐受尽可能多的有用官能团或实际上受益于尽可能多的有用官能团的方法应该得到广泛的应用。在此，我们证明，简单和容易获得的2-氨基苯甲醛是分子间铑催化的炔加氢酰化的优良底物，并在这样做添加到这些有价值的过程中使用的图案。此外，这些反应的产物，氨基取代的烯酮，直接转化为一系列有用的二氢喹诺酮杂环。Lochow和米勒报道了第一个分子间金属催化的烯烃氢酰化反应，该反应使用具有配位C= C键的醛。[7]自该初始报告以来，用于螯合控制反应的最流行的底物以杂原子配位为特征，并且包括氧（3）、[8]硫（4，5）、[9，10]以及在更有限的程度上磷[11]取代基的系统都已被报道。虽然也有一些使用氮基官能团的先例，但实例很少，并且大多数要么产率低，要么仅限于非常特定的底物。当Suggs在化学计量的威尔金森络合物存在下使用喹啉-8-甲醛（6）作为底物时，他首次报道了氮螯合的使用。[12]吡啶甲基亚胺7首先被Suggs用作可去除或催化螯合基团;[13]然后Jun等人和其他小组取得了重大进展。[14]然而，这些反应需要苛刻的反应方案1。无螯合（a）和螯合控制的分子间炔加氢酰化（B）。最常见的螯合醛基序是...
Alkene and alkyne hydroacylation reactions are archetypal examples of simple addition processes that display excellent atom economy.[1] Both reactions result in the formation of a new CÀC bond and deliver synthetically useful carbonylcontaining products.[2] In recent years, there has been considerable interest in converting these processes into synthetically useful transformations. Transition-metal-catalyzed variants represent the largest class of hydroacylation reactions, and amongst these, processes that involve some form of chelation control dominate. The need to employ a chelating substrate stems from the fact that the majority of the metal-catalyzed examples proceed through an inherently unstable acyl metal intermediate 1 (Scheme 1), which can lead to the formation of unwanted side products formed by decarbonylation. A limitation of the chelation-controlled strategy is that the coordinating group, which is present to stabilize the metal–acyl intermediate 2, will also be present in the product. If this group is not needed in the final product, then it must be removed or converted into an alternative functional group.[3] Despite this limitation, the advantages of this chelationcontrolled process, such as mild reaction conditions, control of enantio-and regioselectivity,[4, 5] and broad substrate scope, have resulted in widespread applications of this approach. One strategy to overcome the innate limitation of a chelationcontrolled approach is to develop catalytic methods that function without the need for such coordinating groups; although there are notable examples of success with this approach,[2c, 6] significant limitations with regard to substrate scope and enantio-and regioselectivity remain. An alternative strategy is to consider the need for a chelating unit as an opportunity, and to expand the range of effective coordinating groups, so that a large variety of useful functional groups can act as the crucial chelating motif. As synthetic chemistry is generally concerned with the preparation of functionalized molecules, an approach that is tolerant of, or indeed benefits from, as many useful functional groups as possible should find wide application. Herein, we demonstrate that simple and readily available 2-aminobenzaldehydes are excellent substrates for intermolecular Rh-catalyzed alkyne hydroacylation, and in doing so add to the motifs available for use in these valuable processes. Furthermore, the products of these reactions, amino-substituted enones, were directly converted into a series of useful dihydroquinolone heterocycles. The first intermolecular metal-catalyzed alkene hydroacylation, which employed an aldehyde with a coordinating C= C bond, was reported by Lochow and Miller.[7] Since this initial report, the most popular substrates for chelationcontrolled reactions feature heteroatom coordination, and systems that include oxygen (3),[8] sulfur (4, 5),[9, 10] and, to a more limited extent, phosphorus [11] substituents have all been reported. Although there are also some precedents for the use of nitrogen-based functional groups, examples are scarce and mostly either poor yielding or limited to very specific substrates. Suggs first reported the use of nitrogen chelation when he employed quinoline-8-carboxyaldehyde (6) as a substrate in the presence of a stoichiometric amount of Wilkinson s complex.[12] Picolyl imines 7 were first used as removable or catalytic chelating groups by Suggs;[13] significant advances were then achieved by Jun et al. and other groups.[14] However, these reactions require harsh reactionScheme 1. Chelation-free (a) and chelation-controlled intermolecular alkyne hydroacylation (b). The most common chelating aldehyde motifs are …
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影响因子：
2.1
作者：
Bhattacharya, R. N.;Kundu, Pradip;Maiti, Gourhari
通讯作者：
Maiti, Gourhari
影响因子：
3.5
作者：
Clemens, B;Ménes, A;Nagy, Z
通讯作者：
Nagy, Z
影响因子：
1.8
作者：
Jo, Eun-Ae;Jun, Chul-Ho
通讯作者：
Jun, Chul-Ho
影响因子：
15
作者：
Coulter, Matthew M.;Kou, Kevin G. M.;Dong, Vy M.
通讯作者：
Dong, Vy M.
影响因子：
3.6
作者：
Imai, M;Tanaka, M;Suemune, H
通讯作者：
Suemune, H