Thermomorphic fluorous imine and thioether palladacycles as precursors for highly active Heck and Suzuki catalysts; evidence for palladium nanoparticle pathways
Thermomorphic fluorous imine and thioether palladacycles as precursors for highly active Heck and Suzuki catalysts; evidence for palladium nanoparticle pathways
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热形氟亚胺和硫醚环钯作为高活性 Heck 和 Suzuki 催化剂的前体；
DOI：
10.1039/b208545n
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发表时间：
2003
影响因子：
3.3
通讯作者：
J. Gladysz
中科院分区：
文献类型：
--
作者：
C. Rocaboy;J. Gladysz
对碘苯甲醛被加工成氟醇p-Rf 8（CH 2）3C 6 H4 CH（OH）（CH 2）2 Rf 8（三步/80%; Rf 8 = n-C8 F17），其被转化成亚胺p-Rf 8（CH 2）3C 6 H4 C（N（CH 2）3Rf 8）（CH 2）2 Rf 8（6，两步/93%）和硫醚p-Rf 8（CH 2）3C 6 H4 CH（S（CH 2）3Rf 8）（CH 2）2 Rf 8（12，64%）。 与钯（醋酸）2（AcOH，95 °C）反应得到具有[RC 6 H3 CR 'N（R）Pd（μ-醋酸）]2（7，87%）和[RC 6 H3 CHR'S（R）Pd（μ-醋酸）]2（13，84%）核的钯环。 前者与LiCl和LiI反应得到相应的桥连卤化物配合物（8，9）; LiCl/PPh 3得到单体RC 6 H3CR ′N（R）Pd（Cl）（PPh 3）（10）。钯环7-9和13在20-24 °C下在许多溶剂中溶解性差或不溶，但在较高温度下溶解性更好。 6、7、12和13的CF 3C 6 F11/甲苯分配系数均大于91∶<9（24 °C）。 7和13是卤代芳烃Heck反应的优良催化剂前体。在140 °C的DMF中，在均相条件下，使用苯基碘的转化数超过106。 钯环在冷却时作为桥卤化物沉淀，并且理论上可以通过液/固相分离来回收。然而，由于量小，所以添加溶剂C8 F17 Br用于再循环。注意到第一和第二周期的诱导期以及活动逐渐降低。透射电子显微镜表明可溶性钯纳米粒子的形成。与其他数据一起，提出纳米颗粒是活性催化剂，可回收的环钯化合物构成稳定状态的来源，直到耗尽。络合物7类似地催化Suzuki反应（K3 PO 4，甲苯，130 °C）。
p-Iodobenzaldehyde is elaborated to the fluorous alcohol p-Rf8(CH2)3C6H4CH(OH)(CH2)2Rf8 (three steps/80%; Rf8 = n-C8F17), which is converted to imine p-Rf8(CH2)3C6H4C(N(CH2)3Rf8)(CH2)2Rf8 (6, two steps/93%) and thioether p-Rf8(CH2)3C6H4CH(S(CH2)3Rf8)(CH2)2Rf8 (12, 64%). Reactions with Pd(OAc)2 (AcOH, 95 °C) give palladacycles with [RC6H3CR′N(R)Pd(μ-OAc)]2 (7, 87%) and [RC6H3CHR′S(R)Pd(μ-OAc)]2 (13, 84%) cores. The former reacts with LiCl and LiI to give the corresponding bridging halide complexes (8, 9); LiCl/PPh3 affords monomeric RC6H3CR′N(R)Pd(Cl)(PPh3) (10). Palladacycles 7–9 and 13 are poorly soluble or insoluble in many solvents at 20–24 °C, but much more soluble at higher temperatures. The CF3C6F11/toluene partition coefficients of 6, 7, 12, and 13 are >91∶<9 (24 °C). Both 7 and 13 are excellent catalyst precursors for Heck reactions of aryl halides. Turnover numbers exceed 106 with phenyl iodide under homogeneous conditions in DMF at 140 °C. The palladacycles precipitate as bridging halides upon cooling, and can in theory be recovered by liquid/solid phase separations. However, since the quantities are small, the solvent C8F17Br is added for recycling. Induction periods in both the first and second cycles, and progressively lower activities, are noted. Transmission electron microscopy indicates the formation of soluble palladium nanoparticles. Together with other data, it is proposed that the nanoparticles are the active catalysts, for which the recyclable palladacycles constitute a steady state source, until exhausted. Complex 7 similarly catalyzes the Suzuki reaction (K3PO4, toluene, 130 °C).