The present invention provides novel imidazole analogs of Formula I which are potent inhibitors of spleen tyrosine kinase, and are useful in the treatment and prevention of diseases mediated by said enzyme, such as asthma, COPD, rheumatoid arthritis, and cancer.
High Turnover Remote Catalytic Oxygenation of Alkyl Groups: How Steric Exclusion of Unbound Substrate Contributes to High Molecular Recognition Selectivity
作者:Siddhartha Das、Gary W. Brudvig、Robert H. Crabtree
DOI:10.1021/ja076039m
日期:2008.2.6
H-bonding mediated molecularrecognitionbetween substrate and ligand -COOH groups orients the substrate so that remote, catalyzed oxygenation of an alkyl C-H bond by a Mn-oxo active site can occur with very high (>98%) regio- and stereoselectivity. This paper identifies steric exclusion-exclusion of non H-bonded substrate molecules from the active site-as one requirement for high selectivity, along
底物和配体 -COOH 基团之间的 H 键介导的分子识别使底物定向,从而可以以非常高 (>98%) 的区域和立体选择性发生 Mn-氧代活性位点对烷基 CH 键的远程催化氧化。本文将非 H 键合底物分子与活性位点的空间排阻-排除作为高选择性的一项要求,以及分子内的熵优势。如果未结合的底物分子能够到达活性位点,它们就会无选择性地反应,从而降低观察到的选择性。催化剂的两个面都被两个配体分子封闭,每个配体分子都带有 -COOH 基团。酸 p-(t)BuC6H4COOH 与配体 -COOH 识别位点结合,但不会被氧化,仅阻止底物的接近,因此在游离酸和布洛芬酯形式中均作为布洛芬氧化的有效抑制剂。Dixon 图显示抑制作用与游离酸布洛芬底物竞争,这无疑是因为该底物可以与抑制剂竞争结合识别位点。相比之下,抑制作用对布洛芬酯底物没有竞争性,这与该酯底物不再能够与识别位点结合是一致的。抑制作用可以用 MeCOOH