The reactivity, as electrogenerated bases, of chiral and achiral phenazine radical-anions, including application in asymmetric deprotonation
作者:A. Mateo Alonso、Roberto Horcajada、Majid Motevalli、James H. P. Utley、Peter B. Wyatt
DOI:10.1039/b506309d
日期:——
Radical-anions, electrochemically generated in aprotic solvent from C(2) symmetric homochiral phenazine derivatives, act as chiral electrogenerated bases (EGBs) in the desymmetrisation by selective deprotonation of a prochiral epoxide (3,4-epoxy-2,3,4,5-tetrahydrothiophene-1,1-dioxide); the anion produced is trapped by mesitoic anhydride. The phenazines may be recovered in high yield by air oxidation
从C(2)对称同手性吩嗪衍生物在质子惰性溶剂中电化学生成的自由基阴离子,通过手性前环氧化物的选择性去质子化作用,在去对称化中作为手性电生成碱(EGBs)(3,4-epoxy-2,3,4, 5-四氢噻吩-1,1-二氧化物); 所产生的阴离子被mesitoic酸酐捕获。吩嗪可以通过空气氧化以高收率回收。对映体过量适度(8-34%),但这是我们所知,这种立体选择性电化学引发的去质子化的首次证明。吩嗪自由基阴离子作为EGB的反应性也已通过测量质子转移速率进行了探索。发现前手性环氧化物具有与甲基三苯基phosph阳离子相似的动力学酸度。