Iron-catalyzed asymmetric epoxidation of aromatic alkenes using hydrogen peroxide
Iron-catalyzed asymmetric epoxidation of aromatic alkenes using hydrogen peroxide
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DOI：
10.1002/anie.200701235
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Beller, Matthias
中科院分区：
文献类型：
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作者：
Gelalcha, Feyissa Gadissa;Bitterlich, Bianca;Beller, Matthias
光学活性氧烷是合成精细化学品和药物的关键构件。[1]它们可以从拆分过程中获得[2]，更有趣的是，它们可以从催化不对称环氧化中获得。目前最先进的方案是烯丙醇的夏普莱斯环氧化，[3]使用手性Mn(Salen)催化剂(Salen=N，N‘-双(水杨基)乙二胺)，[4]和使用手性酮和氧酮(2 KHSO5·KHSO4·K2SO4)的有机催化方法对未官能化的烯烃进行Katsuki-Jacobsen环氧化[3]。在各种氧化剂中，过氧化氢是最实用的试剂之一(在成本和原子效率方面仅次于空气)。[5]尽管已知的方法有用，但开发更便宜、更环保的催化剂和氧化剂体系是有机合成的主要目标。在各种氧化剂中，过氧化氢是最实用的试剂之一(仅次于空气)。近年来，过氧化氢不仅对本体环氧化越来越重要，而且对不对称催化也越来越重要。在这方面，Katsuki和他的同事们的工作最为引人注目，他们开发了方便的钛催化剂，用于不对称烯烃的过氧化氢环氧化。[7]此外，还报道了铂[8]和Ru催化剂[9]用于不对称环氧化烯烃。虽然这些体系具有很高的对映体选择性，但所涉及的催化剂相对昂贵。自然界依赖于各种含铁的酶来氧化降解一些外来物质，通常具有极高的选择性。铁不仅普遍存在，而且是用途最广的过渡金属之一。[10]因此，使用铁基催化剂进行环氧化反应的研究在很大程度上被忽视了，这是令人惊讶的。直到最近，才报道了一种成功的仿生方法，用铁的卟啉络合物以碘苯为氧化剂催化苯乙烯衍生物的环氧化。[11]不幸的是，合成所需的手性卟啉配体是出了名的困难，[12]而且氧化剂对环境不友好。此外，程等人还提出了一些新的结论。最近报道了三(d，d-二苯基甲烷)铁(III)配合物[Fe(DCM)3]催化的苯乙烯衍生物的好氧环氧化反应。
Optically active oxiranes are key building blocks for the synthesis of fine chemicals and pharmaceuticals.[1] They are available from resolution processes [2] and more interestingly from catalytic asymmetric epoxidations. State-of-the-art protocols are the Sharpless epoxidation of allylic alcohols,[3] the Katsuki–Jacobsen epoxidation of unfunctionalized alkenes using chiral Mn (salen) catalysts (salen= N, N’-bis (salicylidene) ethylenediamine),[4] and organocatalytic methods using chiral ketones and oxone (2 KHSO5· KHSO4· K2SO4).[5] Despite the usefulness of the known procedures, the development of less expensive and environmentally more benign catalysts and oxidant systems is a major goal for organic synthesis.Among the various oxidants, hydrogen peroxide is one of the most practical reagents (second only to air) in terms of cost and atom efficiency. In recent years hydrogen peroxide has become increasingly important not only for bulk epoxidations but also for asymmetric catalyis.[6] In this respect the work of Katsuki and co-workers, who developed convenient Ti catalysts for asymmetric alkene epoxidation with hydrogen peroxide, is most notable.[7] In addition, also Pt [8] and Ru catalysts [9] have been reported for asymmetric epoxidations of olefins. While these systems give high enantioselectivity, the catalysts involved are relatively expensive. Nature relies on various iron-containing enzymes for the oxidative degradation of a number of xenobiotics often with exceptional selectivities. Iron is not only ubiquitous but also one of the most versatile transition metals.[10] Hence, it is surprising that research on epoxidations using iron-based catalysts has largely been neglected. Only recently, a successful biomimetic approach was reported with iron porphyrin complexes for the epoxidation of styrene derivatives applying iodosobenzene as oxidant.[11] Unfortunately, the synthesis of the required chiral porphyrin ligands is notoriously difficult,[12] and the oxidant is not environmentally friendly. Moreover, Cheng et al. reported recently the aerobic epoxidation of styrene derivatives catalyzed by tris (d, d-dicampholylmethanato) iron (III) complex,[Fe (dcm) 3].[13] Although encouraging results were achieved, a drawback of this