Model Studies for New <i>o</i>-Nitrobenzyl Photolabile Linkers: Substituent Effects on the Rates of Photochemical Cleavage
作者:Christopher P. Holmes
DOI:10.1021/jo961602x
日期:1997.4.1
the kinetics of their photolytic cleavage examined in solution. The linkers were prepared by amidation of the carboxylic acid anchoring tether with benzylamine, and the cleavable benzylic substituent was chosen to be either acetic acid or acetamide. Irradiation of the linkers in four solvents (methanol, p-dioxane, and aqueous buffer +/- dithiothreitol) at 365 nm and analysis via HPLC afforded kinetic
制备了来自文献的模型苯甲酰基和邻硝基苄基光不稳定连接基,以及四个新的邻硝基苄基连接基,并在溶液中检查了其光解裂解的动力学。通过将羧酸锚定系链与苄胺酰胺化来制备接头,并且将可裂解的苄基取代基选择为乙酸或乙酰胺。接头在365 nm的四种溶剂(甲醇,对二恶烷和水性缓冲液+/-二硫苏糖醇)中进行辐照,并通过HPLC分析提供了适合比较目的的裂解动力学速率。发现苯甲酰基接头在水性条件下缓慢裂解,在有机溶剂中未观察到可裂解。已知的邻硝基苄基接头4在水性和有机溶剂中显示出适度的裂解速率。在苯环中引入两个烷氧基以生成基于藜芦基的连接基13a显着提高了裂解速率,另外引入苄基甲基(13b)使裂解速率增加了5倍。将锚固羧酸系链的长度从乙酸增加为丁酸(19),可以适度改善有机介质中的裂解动力学,并略微降低了在水中的分解速率。酰胺模型接头21的断裂速度比相应的酯键19快3至7倍。制备了酰胺产生接头26,并简要地研究了