Synthesis and Reactivity of Some 6-Substituted-2,4-dimethyl-3-pyridinols, a Novel Class of Chain-Breaking Antioxidants
作者:Maikel Wijtmans、Derek A. Pratt、Johan Brinkhorst、Remigiusz Serwa、Luca Valgimigli、Gian Franco Pedulli、Ned A. Porter
DOI:10.1021/jo048842u
日期:2004.12.1
found to be indefinitely stable to air oxidation while 2 and 3 decomposed upon extended exposure to the atmosphere. The reactivities of the pyridinols toward chain-carrying peroxyl radicals in homogeneous organic solution were examined by studying the kinetics of radical-initiated styrene autoxidations under controlled conditions. These experiments revealed that some of the newly synthesized pyridinols
报道了一系列具有令人感兴趣的抗氧化剂性质的6-取代的2,4-二甲基-3-吡啶基醇的合成和研究。导致化合物的一般合成策略是将低温芳基溴化物转化为酒精,这是最后一步。由此制备了2,4-二甲基-3-吡啶醇(1a),2,4,6-三甲基-3-吡啶醇(1b)和2,4-二甲基-6-(二甲基氨基)-3-吡啶醇(1d)。得自相应的3-溴吡啶前体。甲氧基衍生物2,4-二甲基-6-(甲氧基)-3-吡啶醇(1c)也通过替代路线,通过Baeyer-Villiger反应在取代的苯甲醛前体上制备。新型双环吡啶并2和3需要事先构造环形结构。因此,2是通过6步分子内Friedel-Crafts策略制备的,3则需要11步序列,嘧啶环和炔烃之间的热解分子内反需求Diels-Alder反应是关键步骤。吡啶醇的碱性随着环中电子密度的增加而接近生理pH。发现吡啶酮1a - d对空气氧化具有无限的稳定性,而2和3长时间暴露在大气中会分