Fluxional Cyclic Seleninate Ester: NMR and Computational Studies, Glutathione Peroxidase-like Behavior, and Unexpected Rearrangement
作者:Nicole M. R. McNeil、Marie C. Matz、Thomas G. Back
DOI:10.1021/jo401757m
日期:2013.10.18
trifluoroacetic acid. Computational studies indicated an activation energy of 12.3 kcal mol–1 for hydroxyl interchange at selenium, comparable to the value of 15.5 kcal mol–1 derived from the NMR experiments. The glutathione peroxidase-like activity of 4 was measured in an assay where the catalysis of the reduction of hydrogen peroxide with benzyl thiol was monitored by the appearance of dibenzyl disulfide. The
取决于条件,用过氧化氢氧化烯丙基亚硒酸酯12产生相应的烯丙基亚硒酸酯12,环状硒代酸酯4或重排的O-烯丙基硒代酸酯18。硒化物12及其氘代的巴豆基类似物27的交叉实验表明,分子内重排通过分子内途径进行,其中烯丙基或巴豆基基团通过其远端碳原子易位至羟甲基官能团。环状硒代酸酯4的可变温度NMR实验揭示了在室温下由三氟乙酸催化的通量行为。计算研究表明,硒处羟基交换的活化能为12.3 kcal mol –1,与NMR实验得出的15.5 kcal mol –1的值相当。在测定中测量了谷胱甘肽过氧化物酶样活性4,其中通过二苄基二硫化物的出现监测了过氧化氢被苄基硫醇还原的催化作用。4的催化活性是未取代硒代硒酸酯2的两倍,但受到相对惰性的硒烯基硫醚32竞争性积累的限制,从而导致与主要催化循环竞争的失活途径。