Functional Development and Reaction Mechanism of Model Oxygenase Complexes

以钴-席夫碱配合物[Co(Sb)]为模型氧化还原体系，在催化氧化过程中得到了以下结果。Co^&lt；111&gt；(Salpr)(OH)是一种配位饱和的羟基钴(III)席夫碱配合物，它能促进邻羟基二苯甲酰甲烷在甲醇中氧化成黄酮类和逆克莱森反应产物(色满酮)。通过假设Co(Sb)(OH)的碱催化作用，使结果更加合理，并为合成色满酮和黄酮类化合物提供了一条新的途径。配位不饱和Co^&lt；111&gt；(Sb)(OH)配合物催化4-取代苯乙炔在乙醇中的氧化反应，导致氧高度选择性地结合到三键上，得到相应的苯乙酮、扁桃酸酯和苯乙氧基酯。Co(Sb)催化叔丁基氢过氧化氢氧化仲芳胺选择性脱氢生成相应的亚胺。在该反应条件下，不受O2/Co(Sb)氧化体系影响的叔胺类化合物发生氧化反应，生成与P450体系相似的产物。所提出的机理涉及电子从底物中的氮原子向叔丁基过氧钴(III)络合物中间体原位生成的叔丁氧基或叔丁基过氧基转移。发现Co(Sb)催化NaOCI氧化烯烃，生成环氧化物为主，1，2-二氯和氯醇化合物为主要产物。反应速度取决于钴催化剂的性质以及烯烃底物的结构。所提出的机理涉及速率决定形成Co^&lt；111&gt；(SB)(OCI)^-，这是一种水溶性的绿色络合物，随后Co-O键的均质断裂产生C10，C10与底物反应得到产物。

The following results are obtained in catalytic oxidation processe using cobalt schiff base complexes [Co(SB)] as model oxidoreductases.1. Co^<111>(salpr)(OH), a coordinately saturated hydroxocobalt (III) Schiff base complex, has been found to promote the oxygenation of o-hydroxydibenzoylmethane to flavones and retro-Claisen reaction products (chromanones) in methanol. The results are rationalized by assuming base catalysis of Co(SB)(OH) and provide complexes a new route to the synthesis of chromanones and flavones.2. Coordinately unsaturated Co^<111>(SB)(OH) complexes catalyze the oxygenation of 4-substituted phenylacetylenes in alcohol resulting in highly selective incorporation of dioxygen into the triple bond to give the corresponding acetophenones, mandelic and phenylglyoxylic esters.3. Co(SB) catalyzed oxidation of secondary aromatic amines with t-butyl hydroperoxide results selectively in dehydrogenation to give the corresponding imines. Under the reaction conditions, amines including tertiary amines which are not susceptible to the O_2/Co(SB) oxidation system undergo the oxidation to gives the products similar to those obtained in the P450 system. Proposed mechanism involves electron transfer from the nitrogen atom in the substrate to t-butyloxyl or t-butylperoxyl radical produced in situ from a t-butylperoxocobalt (III) complex intermediate.4. Co(SB) are found to catalyze the oxidation of alkenes with NaOCI to give mainly epoxides together with 1,2-dichloro and chlorohydrin compounds as the primary products. The reaction rate depends on the nature of the cobalt catalyst as well as the structure of the alkene substrate. Proposed mechanism involves rate determining formation of Co^<111>(SB)(OCI)^-, a water soluble green complex followed by homolytic cleavage of the Co-O bond giving rise to C10, which reacts with the substrate to gives the products.