Palladium-catalyzed highly regioselective 2-arylation of 2,x-dibromopyridines and its application in the efficient synthesis of a 17β-HSD1 inhibitor
摘要:
2,3- and 2,5-Dibromopyridines reacted with arylboronic acids, catalyzed by Pd(OAc)(2)/PPh3 in the presence of K2CO3 in CH3CN/MeOH (2:1) at 50 degrees C for 24 h, to afford 2-aiylpyridines in good to high yields, while 2,4-dibromopyridine reacted with arylboronic acid pinacol esters, catalyzed by Pd(OAc)(2)/PPh3 in the presence of KOH in CH3CN at 70 degrees C for 24 h, to afford 2-arylpyridines in good to high yields. To expand this methodology, a 170-HSD1 inhibitor was synthesized in good yield. (C) 2013 Elsevier Ltd. All rights reserved.
Transition-Metal-Mediated Synthesis of Trifluoroethyl Aryl Ethers
作者:Zhiqiang Weng、Yangjie Huang、Ronglu Huang
DOI:10.1055/s-0035-1560054
日期:——
A series of well-definedcopper(I) fluoroalkoxidecomplexes, [(phen)2Cu][OCH2RF], have been shown to undergo trifluoroethoxylation, pentafluoropropoxylation, and tetrafluoropropoxylation with aryl and heteroarylbromides to generate the corresponding trifluoroethyl, pentafluoropropyl, and tetrafluoropropyl (hetero)aryl ethers in good to excellent yields. The reaction tolerates a variety of functional
solvent, an array of xanthenes, thiazole, pyrazine, and pyridazine are compatible with this new arylation approach. The broad substrate scope, mild reaction conditions, and use of water as reaction solvent make this procedure a practical and environmentally friendly method for the synthesis of compounds containing aryl‐heteroaryl motifs.
已经开发出一种高效的可见光促进的N-杂芳烃与芳基重氮盐在水中的“自由基型”偶联。在室温下将反应继续进行的[Ru(联吡啶)3 ]氯2 ⋅ 6 H 2O作为光敏剂,商用灯泡作为光源。在这些反应条件下,吡啶和各种取代的吡啶是有效的底物,仅形成具有不同区域选择性的单取代产物。使用甲酸水溶液作为溶剂,一系列的黄嘌呤,噻唑,吡嗪和哒嗪与这种新的芳基化方法兼容。广泛的底物范围,温和的反应条件以及使用水作为反应溶剂,使得该程序成为合成具有芳基-杂芳基基序的化合物的实用且环境友好的方法。
Bridging the Gap from Mononuclear Pd<sup>II</sup> Precatalysts to Pd Nanoparticles: Identification of Intermediate Linear [Pd<sub>3</sub>(XPh<sub>3</sub>)<sub>4</sub>]<sup>2+</sup> Clusters as Catalytic Species for Suzuki–Miyaura Couplings (X = P, As)
作者:Kate M. Appleby、Evans Dzotsi、Neil W. J. Scott、Guan Dexin、Neda Jeddi、Adrian C. Whitwood、Natalie E. Pridmore、Sam Hart、Simon B. Duckett、Ian J. S. Fairlamb
DOI:10.1021/acs.organomet.1c00452
日期:2021.11.8
Tripalladium clusters of the type [Pd3(PPh3)4]2+, wherein three linearly connected Pd atoms are stabilized by phosphine and arsine ligands, have been detected and isolated as intermediates during the reduction of well-defined mononuclear [Pd(OTf)2(XPh3)2] (X = P and X = As, respectively) to Pd nanoparticles (PdNPs). The isolated [Pd3(PPh3)4]2+ cluster isomerizes on broad-band UV irradiation to form
A Dichotomy in Cross-Coupling Site Selectivity in a Dihalogenated Heteroarene: Influence of Mononuclear Pd, Pd Clusters, and Pd Nanoparticles—the Case for Exploiting Pd Catalyst Speciation
作者:Neil W. J. Scott、Mark J. Ford、Neda Jeddi、Anthony Eyles、Lauriane Simon、Adrian C. Whitwood、Theo Tanner、Charlotte E. Willans、Ian J. S. Fairlamb
DOI:10.1021/jacs.1c05294
日期:2021.6.30
Given that Pd speciation, particularly aggregation, is known to lead to the formation of catalytically competent multinuclear Pdn species, the influence of these species on cross-coupling site-selectivity remains largely unknown. Herein, we disclose that multinuclear Pd species, in the form of Pd3-type clusters and nanoparticles, switch arylation site-selectivity from C2 to C4, in 2,4-dibromopyridine cross-couplings
Cyclotriveratrylene-tethered trinuclear palladium(<scp>ii</scp>)–NHC complexes; reversal of site selectivity in Suzuki–Miyaura reactions
作者:Jonathan M. Fowler、Edward Britton、Christopher M. Pask、Charlotte E. Willans、Michaele J. Hardie
DOI:10.1039/c9dt03400e
日期:——
-3-benzylbenzimidazol-2-ylidene, were also synthesised and their crystal structures determined. Complexes C1–C4 are competent catalysts for SuzukiMiyauracross-coupling, and interestingly exhibit a switch in the normal regioselectivity observed for reactions of 2,4-dibromopyridine with aryl boronic acids, usually C2-selective, yielding C4-arylated product preferentially over C2-arylated product.