Nucleophilic Reactions at the Sulfur of Thiiranium and Thiirenium Ions. New Insight in the Electrophilic Additions to Alkenes and Alkynes. Evidence for an Episulfurane Intermediate
作者:Marco Fachini、Vittorio Lucchini、Giorgio Modena、Manuela Pasi、Lucia Pasquato
DOI:10.1021/ja984304l
日期:1999.4.1
The thiiranium hexachloroantimonates 1a, 3, and 5a−c and the thiirenium hexachloroantimonates 6a−c and 7a with exocyclic S-R substituent (R = Me, Et, i-Pr) react at sulfur with dialkyl disulfides R‘ ‘SSR‘ ‘ (R‘ ‘ = Me, Et and R‘ ‘ ≠ R) in CD2Cl2 at 25 °C to give S-R‘ ‘ substituted ions. The reaction rates are affected by the steric hindrance of the substituents at sulfur and at ring carbons. t-2,t
具有环外 SR 取代基 (R = Me, Et, i-Pr) 的六氯锑酸铪 1a、3 和 5a-c 和六氯锑酸铼 6a-c 和 7a 在硫处与二烷基二硫化物 R' 'SSR' ' (R' ' = Me、Et 和 R' ' ≠ R) 在 25 °C 的 CD2Cl2 中得到 SR' ' 取代离子。反应速率受硫和环碳上取代基的空间位阻影响。t-2,t-3-Di-tert-butyl-r-1-methylthiiranium 六氯锑酸盐 (2) 不反应,t-2-tert-butyl-c-3-phenyl-r-1-methylthiiranium (5a) ) 的反应速度比 c-2,t-3-di-tert-butyl-r-1-methylthiiranium 离子 (1a) 快约 100 倍。动力学数据的分析表明,锍硫在环平面中从平行于 C-C 环键的方向受到二硫化物的攻击。这也是确保与钆或钍离子的