Intramolecular Hydrophosphination/Cyclization of Phosphinoalkenes and Phosphinoalkynes Catalyzed by Organolanthanides: Scope, Selectivity, and Mechanism
作者:Michael R. Douglass、Charlotte L. Stern、Tobin J. Marks
DOI:10.1021/ja010811i
日期:2001.10.1
Organolanthanide complexes of the general type Cp'(2)LnE(TMS)(2) (Cp' = eta(5)-Me(5)C(5); Ln = La, Sm, Y, Lu; E = CH, N; TMS = SiMe(3)) serve as effective precatalysts for the rapid intramolecular hydrophosphination/cyclization of the phosphinoalkenes and phosphinoalkynes RHP(CH(2))(n)()CH=CH(2) (R = Ph, H; n = 3, 4) and H(2)P(CH(2))(n)C triple bond C-Ph (n = 3, 4) to afford the corresponding heterocycles
Cp'(2)LnE(TMS)(2) (Cp' = eta(5)-Me(5)C(5); Ln = La, Sm, Y, Lu; E = CH, N;TMS = SiMe(3)) 作为膦烯烃和膦炔烃 RHP(CH(2))(n)()CH=CH(2) (R = Ph, H; n = 3, 4) 和 H(2)P(CH(2))(n)C 三键 C-Ph (n = 3, 4) 分别提供相应的杂环。这些过程的动力学和机械数据表现出与有机镧系元素介导的分子内加氢胺化/环化的相似之处以及明显的差异。本催化循环的周转限制步骤是将碳-碳不饱和键插入 Ln-P 键,然后快速质子化生成的 Ln-C 键。在大约一个半衰期内,速率定律在 [催化剂] 中是一级的,在 [底物] 中是零级的,杂环产物在更高的转化率下会侵入。催化剂的静止状态很可能是镧系膦-磷化物复合物,二聚体 [Cp'(2)YP(H)Ph](2) 被分离出来并具