Rhodium(I)-Catalyzed [4+1] Cycloaddition Reactions of α,β-Unsaturated Imines with Terminal Alkynes for the Preparation of Pyrrole Derivatives
Rhodium(I)-Catalyzed [4+1] Cycloaddition Reactions of α,β-Unsaturated Imines with Terminal Alkynes for the Preparation of Pyrrole Derivatives
复制标题
DOI：
10.1002/anie.200904402
复制
发表时间：
2009-01-01
影响因子：
16.6
通讯作者：
Iwasawa, Nobuharu
中科院分区：
文献类型：
--
作者：
Mizuno, Akio;Kusama, Hiroyuki;Iwasawa, Nobuharu
亚乙烯基配合物因其独特的反应中间体和合成用途而备受关注，并且已经利用各种过渡金属配合物开发了特征反应。 [1]主要反应之一涉及杂原子亲核试剂（例如醇、羧酸盐和氨基甲酸盐）的加成，得到反马尔可夫尼科夫加成产物。 [1]然而，尽管所生产的两性离子中间体具有很高的合成潜力，但将 C= X 键的杂原子添加到亚乙烯基碳原子上却很少实现。 [2]在此，我们报道了铑 (I) 催化的 α, β-不饱和亚胺和末端炔之间的 [4+ 1] 环加成反应，通过将亚胺氮原子加成到亚乙烯基铑中间体来制备合成有用的取代吡咯衍生物。[3]当处理 β-TMS 取代的 α, β-不饱和亚胺 1a 和 1-辛炔 (2a) 的混合物时用催化量的 [{RhCl (coe) 2} 2] 和 PCy3 在甲苯中于 1108℃ 反应 9 小时，以良好的产率获得吡咯 3a（正式的 [4+ 1] 环加成产物）[4]（方案 1）。在此反应中，[{RhCl (coe) 2} 2]以及其他膦配体如PPh3、P(iPr) 3, 1, 4-双(二苯基膦基)丁烷(dppb)和1, 1'-双(二苯基膦基)二茂铁(dppf)几乎没有表现出活性。此外，在 PCy3 存在下，[{RhOH (cod)} 2](cod= 1, 5-环辛二烯)、[Rh (cod) 2] BF4 和 [{IrCl (coe) 2} 2] 也没有显示任何活性。同时，[{RhCl(cod)2}2]/PCy3
Vinylidene complexes have attracted much attention for being unique reactive intermediate and synthetically useful, and characteristic reactions have been developed using various kinds of transition-metal complexes.[1] One of the main reactions involves the addition of heteroatom nucleophiles such as alcohols, carboxylates, and carbamates to give anti-Markovnikov addition products.[1] However, the addition of the heteroatom of C= X bonds to the vinylidene carbon atom has rarely been achieved in spite of the high synthetic potential of the zwitterionic intermediates that are produced.[2] Herein, we report a rhodium (I)-catalyzed [4+ 1] cycloaddition reaction between α, β-unsaturated imines and terminal alkynes for the preparation of synthetically useful, substituted pyrrole derivatives through the addition of the imine nitrogen atom to rhodium vinylidene intermediates.[3]When a mixture of β-TMS-substituted α, β-unsaturated imine 1a and 1-octyne (2a) was treated with a catalytic amount of [{RhCl (coe) 2} 2] and PCy3 in toluene at 1108C for nine hours, pyrrole 3a (a formal [4+ 1] cycloaddition product)[4] was obtained in good yield (Scheme 1). In this reaction [{RhCl (coe) 2} 2], as well as other phosphine ligands such as PPh3, P (iPr) 3, 1, 4-bis (diphenylphosphanyl) butane (dppb), and 1, 1’-bis (diphenylphosphanyl) ferrocene (dppf) showed almost no activity. Also,[{RhOH (cod)} 2](cod= 1, 5-cyclooctadiene),[Rh (cod) 2] BF4, and [{IrCl (coe) 2} 2] in the presence of PCy3 did not show any activity either. Meanwhile,[{RhCl (cod) 2} 2]/PCy3