Catalytic Cyclophanes. Part XI. A flavo-thiazolio-cyclophane as a biomimetic catalyst for the preparative-scale electro-oxidation of aromatic aldehydes to methyl esters
作者:Patrizio Mattei、Fran�ois Diederich
DOI:10.1002/hlca.19970800516
日期:1997.8.11
corresponding methyl esters. Cyclophane 6 shows saturation kinetics, and the turnover number calculated for the oxidation of naphthalene-2-carbaldehyde to methyl naphthalene-2-carboxylate (kcat = 0.22 s−1) is one of the highest reported for an artificial enzyme. Control experiments showed that the catalytic advantages of 6 result from the macrocyclic binding and reaction site as well as from the covalent
通过18步合成(方案3和4)以克为单位制备黄酮-噻唑啉酮-环烷6。该途径涉及非常有效的溴环烷32的制备(13个步骤的收率为37%),可以轻松对其进行修饰以产生各种多重功能化的受体。该溴化物32随后被转化成相应的硼酸,并通过Suzuki偶合连接到7-溴黄素10(方案2),得到黄酮-环烷36。噻唑unit单元然后在36个叔氨基季铵化后被引入。黄酮-噻唑啉酮-环烷6丙酮酸氧化酶的功能模型是,两个修复基团都连接在明确定义的环烷结合位点附近。在碱性甲醇溶液中,6催化芳族醛氧化为相应的甲酯。环环烷6显示出饱和动力学,对于将萘-2-甲醛催化氧化为萘-2-甲酸甲酯(k cat = 0.22 s -1)所计算出的周转数是人工酶报道的最高值之一。对照实验表明6的催化优势这是由于大环结合和反应位点以及两个辅因子与该位点的共价连接所致。催化循环通过在低工作电极电势(相对于Ag / AgCl为-0.3 V )下