Functional Development and Reaction Mechanism of Model Oxygenase Complexes

以钴席夫碱配合物[Co（SB）]为模型氧化还原酶，在催化氧化过程中得到以下结果. Co<111>（salpr）（OH）是一种配位饱和的羟基钴（III）Schiff碱配合物，它能促进邻羟基二苯甲酰甲烷在甲醇中氧化生成黄酮和逆克莱森反应产物（色满酮）.实验结果通过Co（SB）（OH）的碱催化作用得到了合理的解释，并为色满酮和黄酮的合成提供了一条新的途径.配位不饱和Co^<111>（SB）（OH）配合物催化4-取代苯乙炔在醇中的氧化反应，高选择性地将分子氧引入到三键中，生成相应的苯乙酮、扁桃酸和苯乙醛酸酯. Co（SB）催化叔丁基过氧化氢氧化芳香仲胺，选择性脱氢生成相应的亚胺。在反应条件下，对O_2/Co（SB）氧化体系不敏感的胺（包括叔胺）发生氧化反应，得到与P450体系相似的产物。提出的机理涉及电子从底物中的氮原子转移到由叔丁基过氧钴（III）络合物中间体原位产生的叔丁氧基或叔丁基过氧自由基.发现Co（SB）催化NaOCl氧化烯烃主要得到环氧化合物以及作为主要产物的1，2-二氯和氯代醇化合物。反应速率取决于钴催化剂的性质以及烯烃底物的结构。提出的机理涉及Co^<111>（SB）（OCI）^-的形成速率决定，Co ^（SB）（OCI）^-是一种水溶性绿色络合物，随后Co-O键均裂产生C10，C10与底物反应产生产物。

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.