透過您的圖書館登入
IP:34.228.168.200
  • 學位論文

取代基效應對環鈀化反應之影響及耦合催化反應之應用

Substituent Effect on Cyclopalladation of Arylimine Ligands Applied for Suzuki-Miyaura Coupling Reaction

指導教授 : 劉緒宗

摘要


本論文主要在合成一系列不同取代之亞胺配位基,並探討其對進行環鈀化反應之影響,進而利用這些環鈀化金屬錯合物為催化劑進行耦合催化反應,並研究不同環鈀化錯合物催化之活性及可能的反應機制。 第一部份的研究中,在苯環上設計不同電子及立體效應之取代亞胺配位基,利用PdCl2(CH3CN)2與醋酸鈉於溫和的條件下進行環鈀化反應,發現此一反應的進行受到電子效應的影響不大,而是與立體效應上的取代有關,特別是當取代基為第四丁基時,反應無法進行。 經由在配基上之取代基調控,成左漲X成了系列五圓環環鈀化產物,以及在苄基位置進行碳氫活化反應形成六環的環鈀化金屬錯合物,再者這些氯橋鍵之雙核物可進行膦基取代反應,形成單一金屬中心之錯合物,此外亦製備了具有親油及親水長鏈取代的環鈀化屬錯合物。這些錯合物的分子結構皆可經由光譜以及晶體結構鑑定證明。 在Suzuki的耦合催化反應探討中,以環鈀化金屬錯合物為催化劑,對於芳香溴苯與苯基硼酸的耦合反應都有不錯的催化活性,特別是對於質子性(protic)的溶劑與在不除氧的條件下,都能顯出優秀的活性,尤其是六環的環鈀化錯合物。對於拉電子取代的芳香氯苯也有著相似的結果。特別以錯合物14j及14k對於4-甲醯基溴苯的反應為例,在濃度比為[ArBr]/ [Pd] = 106,轉換率可達90 % 以上,而4-甲氧基溴苯在相同的濃度下也可達到60 % 的轉換率,而4-甲醯基氯苯,[ArCl]/ [Pd] = 105時也有接近60% 的轉換率,若[ArCl]/ [Pd] = 104可得將近完全反應之結果。 最後在反應機制的探討上,以不同條件溫度反應時間,可得一系列不同大小之鈀金屬粒子,其中最小的約在12奈米左右,並且此一奈米鈀金屬可作為直接的佐證,做為此些催化反應中的活性物種。

並列摘要


A series of substituted benzylidene- and dialkylarylamines reacted with PdCl2(CH3CN)2 under basic conditions at the room temperature to provide the desired cyclopalladated products (13a-i and 14j-m), even the halo substituted (Le and Lf) arylimines. The steric bulky substituent such as t-butyl on the aryl rings readily inhibits the C-H activation and only yields the simple imine-coordinated complexes (15g and 15g’, 15h). As expected, cyclometallation takes place at the ortho position of the aryl ring resulting in formation of a five-membered chelating ring. However, cyclopalladation readily occurred at benzylic to form an endo six-membered chelating ring with 14j and 14k. The resulting chloro-bridged cyclopalladated complexes underwent ligand substitution with phosphine to give the mono-nuclear palladium complexes. All complexes were characterized by both spectral and elemental analysis. Some palladium complexes were further confirmed by X-ray diffraction analysis. Recent development on the Suzuki- Miyaura coupling reactions has been focused on the use of aryl chloride as substrates under aerobic conditions or even in aqueous solution. Accordingly, palladacycles were found to be the most promising catalysts in this regard. Thus the use of these new palladium complexes as catalysts for Suzuki-Miyaura coupling reactions was investigated in this study. It is found that this series of cyclopalladated complexes do have good catalytic activities on the Suzuki-Miyaura coupling reaction. Complexes 13a-d and 14j-m were thermally stable, not sensitive to moisture and air so that could be applied in the catalysis under aqueous and aerobic conditions. Among these catalysts, both 14j and 14k behave the best activities. Some mechanistic insights concerning this catalysis involving the palladium nano-particles were discussed.

參考文獻


[47] Bahr, J. L.; Yang, J.; Kosynkin, D. V.; Bronikowski, M. J.; Smalley, R. E.; Tour, J. M. J. Am. Chem. Soc. 2001, 123, 6536.
[3] (a) Cope, A. C.; Siekman, R. W. J. Am. Chem. Soc. 1965, 87, 3272. (b) Cope, A. C.; Friedrich, E. C. J. Am. Chem. Soc. 1968, 90, 909.
[1] (a) Parshall, G. W. Acc.Chem.Res. 1970, 3, 139. (b) Dehand, J.; Pfeffer, M. Coord. Chem. Rev. 1976, 18, 327. (c) Bruce, M. I. Angew. Chem., Int. Ed. Engl. 1977, 16, 73. (d) Omae, I. Chem. Rev. 1979, 79, 287.; Chem. Rev. 1988, 83, 137. (e) Constable, E. C. Polyhedron 1984, 3, 1037. (f) Rothwell, I. P. Polyhedron 1985, 4, 177; Acc. Chem. Res. 1988, 21, 153. (g) Newkome, G. R.; Puckett, W. E.; Gupta, V. K.; Kiefer, G. E. Chem. Rev. 1986, 86, 451. (h) Ryabov, A. D. Chem. Rev., 1990, 90, 403. (i) Albert, J.; Granell, J. Trands in Organomet. Chem., 1999, 3, 99.
[2] Trofimenko, S. Inorg. Chem. 1973, 12, 1215
[14] Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. Engl. 2002, 41, 4176.

延伸閱讀