Cyclic acetals as carbonyl blocking groups in the photo-fries rearrangement of acyl substituted aryl esters.
作者:Hermenegildo Garcia、Roberto Martinez-Utrilla、Miguel A. Miranda
DOI:10.1016/s0040-4020(01)96666-9
日期:1985.1
2a,b do not undergo any appreciable change upon irradiation,showing the deactivating effect of the acetyl side chain. Therefore, it is concluded that cyclic acetals are suitable carbonyl blocking groups in order to circumvent the deactivating effect of acyl substituents on the photo-Fries rearrangement of aryl esters.
由相应的羟基苯乙酮经吡啶中的乙酸酐处理,然后再用乙二醇和-甲苯磺酸处理而制得的相应的羟基苯乙酮的乙缩醛和-乙酰氧基苯乙酮3a,b,在辐照后得到预期的光炸产物4a,b(3a)或6(来自3b)。这些化合物由于脱缩醛作用而部分转化为二乙酰基苯酚5a,b,在辐射过程中以及在色谱处理过程中会发生一定程度的脱乙酰作用。光产品的产量和/比率(在3a的情况下)与文献中关于乙酸苯酯的那些非常相似。相反,乙酰氧基苯乙酮2a,b在辐照时没有发生任何明显的变化,显示了乙酰基侧链的失活作用。因此,得出结论,环状缩醛是合适的羰基保护基团,以规避酰基取代基对芳基酯的光-弗里斯重排的减活作用。