Synthesis and X-ray Structure Determination of Highly Active Pd(II), Pd(I), and Pd(0) Complexes of Di(tert-butyl)neopentylphosphine (DTBNpP) in the Arylation of Amines and Ketones
Synthesis and X-ray Structure Determination of Highly Active Pd(II), Pd(I), and Pd(0) Complexes of Di(tert-butyl)neopentylphosphine (DTBNpP) in the Arylation of Amines and Ketones
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DOI：
10.1021/jo101187q
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发表时间：
2010-10-01
影响因子：
3.6
通讯作者：
Woltermann, Christopher J.
中科院分区：
文献类型：
--
作者：
Hill, Lensey L.;Crowell, Jason L.;Woltermann, Christopher J.
空气稳定配合物Pd（eta(3)-烯丙基）（DTBNpP）Cl （DTBNpP =二（叔丁基）新戊基膦）是一种高效的预催化剂，可在温和条件下使用芳基溴化物和氯化物进行胺和烯醇化反应，产率为74%至98%。用1-2 mol %的Pd（eta(3)-烯丙基）（DTBNpP）Cl在23-50℃下进行芳基溴化反应，不需要排除氧气或水分。使用Pd（eta(3)-烯丙基）（DTBNpP）Cl预催化剂，在较低的温度（80-100℃）和催化剂负载（1 mol %）下，与原位由DTBNpP和Pd-2(dba)(3)（100-140℃，2-5 mol % Pd）生成的催化剂相比，芳基氯化物的C- n偶联发生在较低的温度（80-100℃）和催化剂负载（1 mol %）下。其他Pd(DTBNpP)(2)基配合物(Pd(DTBNpP)(2)和Pd（DTBNpP)(2)Cl-2）在相同条件下对胺化反应无效。Pd(DTBNpP)2和Pd(DTBNpP)(2)Cl-2预催化剂在底物/催化剂负载为100/1的情况下，对丙烯酮与对氯甲苯和对溴苯甲醚的α -芳基化反应产物的转化率接近定量。在较低的底物/催化剂负载（1000/1）下，转化率较低，但与Pd（t-Bu3P）相当(2)。在许多情况下，基于三叔丁基膦（TTBP）的Pd(I)二聚体[Pd(mu-Br)(TTBP)](2)在相同条件下是最活跃的烯醇酯芳化催化剂。有趣的是，空气稳定的Pd(I)二聚体Pd-2(DTBNpP)(2)(mu-Cl)（mu-烯丙基）与[Pd(mu-Br)(TTBP)](2)和Pd（eta(3)-烯丙基）（DTBNpP）Cl相比活性较低。本文报道了Pd（eta(3)-烯丙基）（DTBNpP）Cl、Pd(DTBNpP)(2)Cl-2、Pd(DTBNpP)(2)和Pd-2(DTBNpP)(2) (mu-Cl)（mu-烯丙基）的x射线晶体结构，并初步研究了Pd（eta(3)-烯丙基）（DTBNpP）Cl预催化剂的催化剂活化。
The air-stable complex Pd(eta(3)-allyl)(DTBNpP)Cl (DTBNpP = di(tert-butyl)neopentylphosphine) serves as a highly efficient precatalyst for the arylation of amines and enolates using aryl bromides and chlorides under mild conditions with yields ranging from 74% to 98%. Ami nation reactions of aryl bromides were carried out using 1-2 mol % Pd(eta(3)-allyl)(DTBNpP)Cl at 23-50 degrees C without the need to exclude oxygen or moisture. The C-N coupling of the aryl chlorides occurred at relatively lower temperature (80-100 degrees C) and catalyst loading (1 mol %) using the Pd(eta(3)-allyl)(DTBNpP)Cl precatalyst than the catalyst generated in situ from DTBNpP and Pd-2(dba)(3) (100-140 degrees C, 2-5 mol % Pd). Other Pd(DTBNpP)(2)-based complexes, (Pd(DTBNpP)(2) and Pd(DTBNpP)(2)Cl-2) were ineffective precatalysts under identical conditions for the amination reactions. Both Pd(DTBNpP)2 and Pd(DTBNpP)(2)Cl-2 precatalysts gave nearly quantitative conversions to the product in the alpha-arylation of propiophenone with p-chlorotoluene and p-bromoanisole at a substrate/catalyst loading of 100/1. At lower substrate/catalyst loading (1000/1), the conversions were lower but comparable to that of Pd(t-Bu3P)(2). In many cases, the tri-tert-butylphosphine (TTBP) based Pd(I) dimer, [Pd(mu-Br)(TTBP)](2), stood out to be the most reactive catalyst under identical conditions for the enolate arylation. Interestingly, the air-stable Pd(I) dimer, Pd-2(DTBNpP)(2)(mu-Cl)(mu-allyl), was less active in comparison to [Pd(mu-Br)(TTBP)](2) and Pd(eta(3)-allyl)(DTBNpP)Cl. The X-ray crystal structures of Pd(eta(3)-allyl)(DTBNpP)Cl, Pd(DTBNpP)(2)Cl-2, Pd(DTBNpP)(2), and Pd-2(DTBNPP)(2)(mu-Cl)(mu-allyl) are reported in this paper along with initial studies on the catalyst activation of the Pd(eta(3)-allyl)(DTBNpP)Cl precatalyst.