Intramolecular aromatic amination through iron-mediated nitrene transfer
Intramolecular aromatic amination through iron-mediated nitrene transfer
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DOI：
10.1002/anie.200351605
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发表时间：
2003-01-01
影响因子：
16.6
通讯作者：
Que, L
中科院分区：
文献类型：
--
作者：
Jensen, MP;Mehn, MP;Que, L
人们的注意力集中在金属催化的原子和基团转移到有机分子上，作为合成有机化学中碳-杂原子键形成的策略。与同位环氧化反应类似，[1]氮烯（即RN=）转移到烯烃（即氮丙啶化）可以由金属卟啉、[2]铁咔咯、[3]以及低配位铜络合物和盐催化。[4]金属卟啉或细胞色素 P450 也会影响氮烯插入以产生脂肪族 CÀH 键胺化。[5, 6] 相比之下，金属催化的芳烃胺化实际上是未知的，[6] 尽管游离有机氮烯很容易添加到芳烃中。[7]据报道，通过氯化铁 (ii) 和氯胺-T 的未表征的加合物进行亚化学计量和非选择性萘胺化，[8] 以及一些可能类似的有机金属配体转化。 [9]与介导血红素单加氧酶化学反应的含氧铁物种类比，[10] 高价亚氨基复合物通常在这些胺化反应中被用作反应中间体，[2, 11] 尽管铁的亚氨基复合物通常非常罕见。 [12]最近，我们报道了在添加叔丁基氢过氧化物 (tBuOOH) 的驱动下，改性三 (2-吡啶甲基) 胺 (TPA),[(6-PhTPA) FeII (NCCH3) 2]-(ClO4) 2 的非血红素铁 (ii) 复合物上的 α-苯基取代基发生有效的分子内邻羟基化。 [13]间接证据表明形成了氧代铁 (iv) 反应性羟基化物质。鉴于优先使用碘鎓叶立德作为氧烯和氮烯前体，[14] 特别包括将 [(TMC) FeII (OTf) 2] 转化为 [(TMC) FeIV= O](OTf) 2 (TMC= tetra-N-methylcyclam)，[15] 我们研究了 [(6-PhTPA) FeII (NCCH3) 2](ClO4) 2 与碘代苯 (PhIO) 和苯基-N-甲苯磺酰亚胺碘烷 (PhINTs)。我们在此报告了由这些各自的试剂提供的 α-芳香族取代基的有效且选择性的邻位羟基化和胺化反应（方案 1）。 [16, 17] 将 [(6-PhTPA)-FeII (NCCH3) 2] 2+ (1.0 mm，乙腈溶液) 的储备溶液等分试样添加到 PhI= X (X= O, NTs) 试剂的固体样品中，所得结果在室温下，在厌氧条件下或在空气中剧烈搅拌悬浮液。随着固体溶解，最初的浅黄色溶液变成深蓝色； PhINT 需要约 1-2 分钟，PhIO 需要 20-30 分钟。记录了稳定终点发色团的紫外/可见光谱，揭示了明显的 FeIII 配体到金属电荷转移 (LMCT) 带，表明苯基取代基存在不同的邻位取代（图 1）。发现这些条带的强度取决于化学计量比，两种试剂的最大值在约 1.6: 1.0 PhI= X/FeII 处获得，无论是否存在氧气，从而支持方案 1 的化学计量比。进一步添加碘鎓试剂导致这些发色团不可逆漂白。 PhIO 产物发色团与 tBuOOH 反应中观察到的 [(6-(oOC 6H4)-TPA) FeIII (NCCH3)] 2+ 的形成完全一致，并且最大消光与 65% 的产率一致。 [13] PhINTs 衍生的发色团被指定为 [(6-(o-TsN-C6H4)-TPA) FeIII (NCCH3)] 2+ 的形成，这是先前表征的邻苯酚复合物的甲苯磺酰苯胺类似物。用冷甲苯沉淀 TsNIPh 产物溶液，得到无定形蓝色粉末，其硫含量与！ 63% 纳入
Much attention has been concentrated on metal-catalyzed atom and group transfers to organic molecules as a strategy for carbon–heteroatom bond formation in synthetic organic chemistry. Similar to isolobal epoxidation reactions,[1] nitrene (that is, RN=) transfer to olefins (that is, aziridination) can be catalyzed by metalloporphyrins,[2] iron corroles,[3] as well as low-coordinate copper complexes and salts.[4] Nitrene insertions to give aliphatic CÀH bond aminations have also been effected by metalloporphyrins or cytochromeP450.[5, 6] In contrast, metal-catalyzed arene amination is practically unknown,[6] even though free organonitrenes will readily add to aromatics.[7] Substoichiometric and unselective naphthalene amination by an uncharacterized adduct of iron (ii) chloride and chloramine-T has been reported,[8] along with a handful of possibly analogous organometallic ligand transformations.[9] By analogy to oxoiron species that mediate heme monooxygenase chemistry,[10] high-valent imido complexes are typically invoked as reactive intermediates in these amination reactions,[2, 11] although imido complexes of iron are generally very rare.[12] Recently, we reported the efficient intramolecular ortho-hydroxylation of an α-phenyl substituent on a non-heme iron (ii) complex of modified tris (2-pyridylmethyl) amine (TPA),[(6-PhTPA) FeII (NCCH3) 2]-(ClO4) 2, driven by added tert-butyl hydroperoxide (tBuOOH).[13] Indirect evidence suggested the formation of an oxoiron (iv) reactive hydroxylating species. Given the precedence for the use of iodonium ylides as oxene and nitrene precursors,[14] specifically including the conversion of [(TMC) FeII (OTf) 2] to [(TMC) FeIV= O](OTf) 2 (TMC= tetra-N-methylcyclam),[15] we investigated the reactivity of [(6-PhTPA) FeII (NCCH3) 2](ClO4) 2 with iodosobenzene (PhIO) and phenyl-N-tosylimidoiodinane (PhINTs). We report herein efficient and selective ortho-hydroxylation and amination reactions of the α-aromatic substituent afforded by these respective reagents (Scheme 1).[16, 17] Aliquots of a stock solution of [(6-PhTPA)-FeII (NCCH3) 2] 2+(1.0 mm in acetonitrile) were added to solid samples of the PhI= X (X= O, NTs) reagents, and the resulting suspensions were stirred vigorously at room temperature, either anaerobically or in air. The initially pale-yellow solutions turned dark blue as the solids dissolved; this required about 1–2min for PhINTs, and 20–30min for PhIO. UV/Vis spectra of the stable endpoint chromophores were recorded, revealing distinct FeIII ligand-to-metal chargetransfer (LMCT) bands suggestive of differential ortho substitutions of the phenyl substituent (Figure 1). The intensities of these bands were found to depend on the stoichiometric ratio, with maxima obtained at approximately 1.6: 1.0 PhI= X/FeII for both reagents, irrespective of the presence of oxygen, thus supporting the stoichiometry of Scheme1. Further addition of iodonium reagents resulted in irreversible bleaching of these chromophores. The PhIO product chromophore was entirely consistent with the formation of [(6-(oOC 6H4)-TPA) FeIII (NCCH3)] 2+, as observed in the tBuOOH reaction, and the maximum extinction was consistent with a 65% yield.[13] The PhINTsderived chromophore was assigned to formation of [(6-(o-TsN-C6H4)-TPA) FeIII (NCCH3)] 2+, the tosylanilide analogue of the previously characterized ortho-phenolate complex. Precipitation of the TsNIPh product solution with cold toluene afforded an amorphous blue powder, the sulfur content of which was consistent with! 63% incorporation of