Johnson Matthey Catalysis & Chiral Technologies, Orchard Road, Royston, SG8 5HE, UK.
J Org Chem. 2011 Oct 7;76(19):7918-32. doi: 10.1021/jo2013324. Epub 2011 Sep 8.
A series of Pd(R-allyl)LCl complexes [R = H, 1-Me, 1-Ph, 1-gem-Me(2), 2-Me; L = Q-Phos, P(t-Bu)(3), P(t-Bu)(2)(p-NMe(2)C(6)H(4)), P(t-Bu)(2)Np] have been synthesized and evaluated in the Buchwald-Hartwig aminations in detail, in addition to the preliminary studies on Suzuki coupling and α-arylation reactions. Pd(crotyl)Q-PhosCl (9) was found to be a superior catalyst to the other Q-Phos-based catalysts, and the reported in situ systems, in model coupling reactions involving 4-bromoanisole substrate with either N-methylaniline or 4-tert-butylbenzeneboronic acid. Precatalyst 9 also performed better than the catalysts bearing P(t-Bu)(2)(p-NMe(2)C(6)H(4)) ligand; however, it is comparable to the new crotyl catalysts bearing P(t-Bu)(3) or P(t-Bu)(2)Np ligands. In α-arylation of a biologically important model substrate, 1-tetralone, Pd(allyl)P(t-Bu)(2)(p-NMe(2)C(6)H(4))Cl (15) was found to be the best catalyst. The reason for the relatively higher activity of the crotyl complexes in comparison to the allyl derivatives in C-N bond formation reactions was investigated using X-ray crystallography in conjunction with NMR spectroscopic studies.
已合成了一系列 Pd(R-烯丙基)LCl 配合物[R = H, 1-Me, 1-Ph, 1-二甲基硅基(2), 2-Me; L = Q-Phos, P(t-Bu)(3), P(t-Bu)(2)(p-NMe(2)C(6)H(4)), P(t-Bu)(2)Np]，并详细研究了它们在 Buchwald-Hartwig 胺化反应中的应用，此外还对 Suzuki 偶联和 α-芳基化反应进行了初步研究。Pd(crotyl)Q-PhosCl（9）被发现是优于其他 Q-Phos 基催化剂的催化剂，并且优于报道的原位体系，在涉及 4-溴苯甲醚底物与 N-甲基苯胺或 4-叔丁基苯硼酸的模型偶联反应中。前体 9 的性能也优于带有 P(t-Bu)(2)(p-NMe(2)C(6)H(4))配体的催化剂；然而，它与带有 P(t-Bu)(3)或 P(t-Bu)(2)Np 配体的新型 crotyl 催化剂相当。在生物重要模型底物 1-四氢萘的 α-芳基化反应中，Pd(allyl)P(t-Bu)(2)(p-NMe(2)C(6)H(4))Cl（15）被发现是最佳催化剂。用 X 射线晶体学结合 NMR 光谱研究研究了 crotyl 配合物在 C-N 键形成反应中比烯丙基衍生物具有相对较高活性的原因。
