Solid and Crystalline State-specific Photoreaction of Organocobalt complexes with small molecules

我们以前发现了（ω-取代烷基）双（二甲基乙醛肟基）钴（III）配合物（ω=β或γ）的固态特异性和单向光异构化以及手性晶格控制的（β→α和γ→β→α）光异构化，这些光异构化仅发生在固态和晶态（对映体选择性：约91%ee）。这些反应具有许多优良的特点，但也存在一些不足。为了改善这些缺点，并且也为了探索新的反应，特别是分子间反应，认为有必要修饰面内配体上的外围位置。我们研究了具有用大体积取代基修饰的面内配体的（ω-取代的烷基）钴肟络合物（R =苯基或呋喃基），这导致更高的对映体选择性（β-甲氧羰基乙基络合物的光异构化中约85%ee）以及更高的反应速率。当取代基X是在键合到的碳处稳定基团的基团时， ...更多信息 X，并使α-烷基络合物（X=Ph，OPh等）的Co-C键失稳。在空间和/或电子上，仅在（ω→α）异构化之后才有效地发生独特的（固态特异性的）二氧化反应。(When取代基是稳定Co-C键和烷基的基团，发生异构化得到α-取代的烷基络合物，该络合物相当难以转化为双氧插入产物）。基于X射线结构研究，发现反应速率主要由反应基团周围的反应腔的体积和形状控制。手性胺配位的（3-苯基丙基）钴肟（X = Ph）的双氧插入反应是对映选择性进行的（-74%ee），尽管存在分子间的自由基反应，但异构化和随后的氧化反应中的不对称诱导的发生，这两个过程都是通过自由基中间体进行的，可以说是固态和晶态反应中最值得注意的特征之一。少

We have previously found solid state-specific and unidirectional photoisomerizations and chiral-crystal-lattice-controlled (β→α and γ→β→α) photoisomerizations of (ω-substituted alkyl)bis-(dimethylglyoximato)cobalt(III) complexes (ω=β or γ) which occur only in the solid-state and crystalline- state (enantioselectivities:〜91%ee). The reactions have many excellent characteristics, but some disadvantages exist as well. To improve these disadvantages and also to explore novel reactions, especially intermolecular reactions, it was considered essential to modify the peripheral position on in-plane ligands.Thus, we examined the photoreactions of (ω-substituted alkyl)cobaloxime complexes having in-plane ligands modified with bulky substituents (R = phenyl or furyl) which resulted in higher enantioselectivities (〜85%ee in the photoisomerization of β-methoxycarbonylethyl complexes) as well as in higher reaction rates. When substituent X is a group to stabilize the radical at the carbon bonded to … More X and also to destabilize the Co-C bond of α-alkyl complex (X=Ph, OPh etc.) sterically and/or electronically, a unique (solid-state-specific) dioxygenation reaction took place efficiently only after (ω→α) isomerization. (When the substituent is a group to stabilize both the Co-C bond and the alkyl radical, isomerization occurred to give α-substituted alkyl complex which is considerably difficult to convert into the dioxygen-insertion product). Based on the X-ray structural studies, the reaction rate was found to be primarily controlled by the volume and shape of the reaction cavity surrounding a reactive group. The dioxygen-insertion reaction proceeded enantioselectively (-74%ee) in cases of chiral amine-coordinated (3-phenylpropyl)cobaloximes (X = Ph), in spite of the intermolecular radical reaction.The occurrence of asymmetric induction in isomerization and the succeeding oxygenation, both of which proceed through radical intermediates, can be said to be one of the most noteworthy characteristics of solid and crystalline-state reactions. Less