Oxygen-atom transfer from iodosylarene adducts of a manganese(IV) salen complex: effect of arenes and anions on I(III) of the coordinated iodosylarene.
Oxygen-atom transfer from iodosylarene adducts of a manganese(IV) salen complex: effect of arenes and anions on I(III) of the coordinated iodosylarene.
复制标题
DOI：
10.1021/ic401270j
复制
发表时间：
2013-08
影响因子：
4.6
通讯作者：
Chunlan Wang;T. Kurahashi;K. Inomata;M. Hada;H. Fujii
中科院分区：
文献类型：
--
作者：
Chunlan Wang;T. Kurahashi;K. Inomata;M. Hada;H. Fujii
本文报道了锰 (IV) salen 络合物的碘代芳烃加合物的制备、表征和反应性。为了系统地研究控制反应性和选择性的空间和电子因素，我们从碘代苯、碘代均三甲苯、2,4,6-三乙基碘代苯和五氟碘代苯制备了碘代芳烃加合物。我们还使用氯离子、苯甲酸根和对甲苯磺酸根研究了阴离子对 I(III) 的影响。使用 (1)H NMR、电子顺磁共振、红外光谱和电喷雾电离质谱进行的光谱研究表明，这些碘代芳烃加合物是带有两个碘代芳烃作为外部轴向配体的锰 (IV) 配合物。在准一级条件下与茴香硫醚的反应表明，I(III)上的吸电子五氟苯基和对甲苯磺酸根阴离子显着加速了氧原子转移。红外光谱和质谱表明，高反应性与 I-OMn 键减弱相关。与苯乙烯的化学计量反应表明，对映选择性和非对映选择性均取决于芳烃和配位碘代芳烃 I(III) 上的阴离子。值得注意的是，五氟苯基和对甲苯磺酸根阴离子抑制顺式-β-甲基苯乙烯环氧化中的顺反异构化。目前的结果表明，锰（IV）salen配合物的碘代芳烃加合物确实是活性氧原子转移试剂，其反应性和选择性受芳烃和配位碘代芳烃I（III）上阴离子的空间和电子性质的调节。
This paper reports preparation, characterization, and reactivity of iodosylarene adducts of a manganese(IV) salen complex. In order to systematically investigate steric and electronic factors that control reactivity and selectivity, we prepared iodosylarene adducts from iodosylbenzene, iodosylmesitylene, 2,4,6-triethyliodosylbenzene, and pentafluoroiodosylbenzene. We also investigated the effect of anions on I(III) by using chloride, benzoate, and p-toluenesulfonate. Spectroscopic studies using (1)H NMR, electron paramagnetic resonance, infrared spectroscopy, and electrospray ionization mass spectrometry show that these iodosylarene adducts are manganese(IV) complexes bearing two iodosylarenes as external axial ligands. Reactions with thioanisole under the pseudo-first-order conditions show that the electron-withdrawing pentafluorophenyl group and the p-toluenesulfonate anion on I(III) significantly accelerate the oxygen-atom transfer. The high reactivity is correlated with a weakened I-OMn bond, as indicated by IR spectroscopy and mass spectrometry. Stoichiometric reactions with styrenes show that both enantioselectivity and diastereoselectivity are dependent on the arenes and anions on I(III) of the coordinate iodosylarenes. Notably, the pentafluorophenyl group and the p-toluenesulfonate anion suppress the cis-to-trans isomerization in the epoxidation of cis-β-methylstyrene. The present results show that iodosylarene adducts of manganese(IV) salen complexes are indeed active oxygen-atom-transfer reagents and that their reactivity and selectivity are regulated by steric and electronic properties of the arenes and anions on I(III) of the coordinated iodosylarenes.