Formation of an aza-nickelacycle by reaction of an imine and an alkyne with nickel(0): Oxidative cyclization, insertion, and reductive elimination
Formation of an aza-nickelacycle by reaction of an imine and an alkyne with nickel(0): Oxidative cyclization, insertion, and reductive elimination
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DOI：
10.1002/anie.200700688
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Kurosawa, Hideo
中科院分区：
文献类型：
--
作者：
Ogoshi, Sensuke;Ikeda, Haruo;Kurosawa, Hideo
过渡金属氧化环化是同时构建一个碳-碳键和两个碳-金属键的有效方法，迄今为止已经报道了多种涉及两个p组分与过渡金属氧化环化的催化反应。例如，已知由炔和醛、酮或亚胺衍生的杂镍环在两类催化反应中作为关键中间体发挥重要作用[1 - 3]，即杂镍环与烷基金属化合物或还原试剂反应生成烯丙醇或烯丙胺[1，[2]和通过在二氢呋喃中插入第二个炔而生成的七元氧-镍环的还原消除而形成吡喃1,2 -二氢吡啶也是两个炔和一个亚胺（方案1）的[2+ 2+ 2]环加成反应的可能产物，尽管尚未有此类反应的报道。氮-镍环的形成可能被证明是这个反应成功的关键，尽管迄今为止只有两个含氮原子的镍环被报道过。[4,5]最近我们报道了由醛或酮的氧化环化和与镍(0)的不饱和碳-碳键形成氧环，因此由亚胺和炔形成氮杂镍环似乎是下一个合乎逻辑的步骤。本文报道了一个亚胺和一个炔与镍(0)氧化环形成一个五元氮杂环-镍吡咯-。本文还讨论了在该环上插入第二个炔得到七元氮杂环-镍二氢氮平-然后还原消除得到1,2 -二氢吡啶，以及这些反应的催化应用。N-（苯磺酰基）苯甲二胺(1)在[Ni (cod) 2]（cod= 1,5 -环二烯）和PCy3（Cy=环己基）存在下与2-丁炔（1等量）在室温下反应10分钟，得到镍吡咯啉（2a）、镍二氢氮平（3a）和h2-亚镍配合物（4；方案2）的不可分离混合物。在该反应混合物中加入一等量的2-丁炔（总当量为2等量），生成3a，其分子结构由x射线晶体学测定（图1），是唯一的产物，产率为95%氧的配位
Oxidative cyclization with transition metals is an efficient method for the simultaneous construction of one carbon–carbon and two carbon–metal bonds, and a variety of catalytic reactions involving the oxidative cyclization of two p components with a transition metal have been reported to date. For example, a hetero-nickelacycle derived from an alkyne and an aldehyde, ketone, or imine is known to play an important role as a key intermediate in two types of catalytic reactions,[1–3] namely the formation of allyl alcohols or allyl amines by reaction of a hetero-nickelacycle with alkylmetal compounds or reducing reagents [1, 2] and the formation of a pyran by reductive elimination from seven-membered oxa-nickelacycles generated by the insertion of a second alkyne into a nickeladihydrofuran.[3] A 1, 2-dihydropyridine is also a possible product of the [2+ 2+ 2] cycloaddition of two alkynes and an imine (Scheme 1), although no such reaction has yet been reported. The formation of aza-nickelacycles might prove to be key to the success of this reaction, although thus far only two nickelacycles containing a nitrogen atom have been reported.[4, 5] Recently we reported the formation of oxanickelacycles by the oxidative cyclization of aldehydes or ketones and an unsaturated carbon–carbon bond with nickel (0),[6] therefore the formation of an aza-nickelacycle from an imine and an alkyne seemed to be the next logical step. Herein we report the formation of a five-membered azanickelacycle—a nickelapyrroline—by the oxidative cyclization of an imine and an alkyne with nickel (0). The insertion of a second alkyne into this ring to give a seven-membered azanickelacycle—a nickeladihydroazepine—followed by reductive elimination to give a 1, 2-dihydropyridine, as well as the catalytic application of these reactions, are also discussed. The reaction of N-(benzenesulfonyl) benzaldimine (1) with 2-butyne (1 equiv) in the presence of [Ni (cod) 2](cod= 1, 5-cyclooctadiene) and PCy3(Cy= cyclohexyl) at room temperature for 10 min gives an inseparable mixture of a nickelapyrroline (2a), a nickeladihydroazepine (3a), and an h2-iminenickel complex (4; Scheme 2). The addition of an additional equivalent of 2-butyne (total 2equiv) to this reaction mixture generates 3a, the molecular structure of which was determined by X-ray crystallography (Figure 1), as the sole product in 95% yield.[7] The coordination of oxygen