A thorough investigation of the challenging Pd-catalyzed fluorination of five-membered heteroaryl bromides is presented. Crystallographic studies and density functional theory (DFT) calculations suggest that the challenging step of this transformation is C-F reductive elimination of five-membered heteroaryl fluorides from Pd(II) complexes. On the basis of these studies, we have found that various heteroaryl bromides bearing phenyl groups in the ortho position can be effectively fluorinated under catalytic conditions. Highly activated 2-bromoazoles, such as 8-bromocaffeine, are also viable substrates for this reaction.
Divergent Synthesis of 1<i>H</i>-Indazoles and 1<i>H</i>-Pyrazoles from Hydrazones<i>via</i>Iodine-Mediated Intramolecular Aryl and<i>sp</i><sup>3</sup>C-H Amination
by condensation of hydrazines with the corresponding ketones. In the presence of potassium iodide, I2-mediated oxidative cyclization of diaryl and tert-butyl aryl ketone hydrazones produced 1H-indazoles via direct aryl C–H amination. Under similar reaction conditions, primary and secondary alkyl ketone hydrazones were transformed into 1H-pyrazole products in a reaction involving sp3 C–H amination. This
Aromatic N-Arylations Catalyzed by Copper-Anchored Porous Zinc-Based Metal-Organic Framework under Heterogeneous Conditions
作者:Tanmoy Maity、Debraj Saha、Subratanath Koner
DOI:10.1002/cctc.201400056
日期:2014.8
A highly porous Zn‐based metal–organicframework (MOF) IRMOF‐3 was covalently decorated with pyridine‐2‐aldehyde. The free amine group of IRMOF‐3 upon condensation with pyridine‐2‐aldehyde affords a bidentate Schiff‐base moiety in the porous matrix. The Schiff base moieties are availed to anchor copper(II) ions to display the catalyst’s utility towards catalytic reactions. The catalyst was characterized
高度多孔的锌基金属-有机骨架(MOF)IRMOF-3与吡啶-2-醛共价修饰。与吡啶-2-醛缩合后,IRMOF-3的游离胺基在多孔基质中提供双齿席夫碱部分。席夫碱部分可用于锚定铜(II)离子,以显示催化剂对催化反应的效用。通过紫外/可见光和红外光谱,粉末XRD光谱,SEM能量色散X射线光谱和氮吸附测量对催化剂进行了表征。在Cs 2 CO 3存在下,在温和条件下(90°C),该催化剂在DMSO介质中催化含氮杂环与芳基溴的N-芳基化反应具有出色的催化活性。。由于MOF的孔内存在活性位点,因此多孔催化剂表现出对底物的尺寸选择性。在多达五个连续的催化循环中,锚固的配合物似乎在催化反应过程中不会被浸出或分解,这显示出优于均相催化的实际优势。
A post-synthetically modified metal–organic framework for copper catalyzed denitrative C–N coupling of nitroarenes under heterogeneous conditions
Ullmann C–Ncouplingreaction of nitroarenes which is achieved by using a copper containing metal–organic framework (MOF) catalyst under heterogenous conditions. The ready availability of nitroarenes and their low cost have made them ideal replacements for haloarenes as electrophilic coupling partners. Notably, the reaction protocol suppresses the by-product formation in the catalytic reaction. The catalyst
An efficientsynthesis of unsymmetrically substituted 1,3-pyrazole derivatives has been developed via three-component coupling reaction involving 3-(dimethylamino)-1-phenylprop-2-en-1-one, hydrazine, and aryl halides in onepot process exhibiting high regioselectivity. The pyrazole synthesis proceeds via a sequential series of reactions such as Michael addition, heterocyclization, dehydration, and
A systematic study of the N-substitution reactions of 3-substituted pyrazoles under basic conditions has been undertaken. Regioselective N1-alkylation, -arylation, and -heteroarylation of 3-substituted pyrazoles have been achieved using K2CO3-DMSO. The regioselectivity is justified by the DFT calculations at the B3LYP/6-31G**(d) level. A consistent steric effect on chemical shift has been observed
对3-取代的吡唑在碱性条件下的N-取代反应进行了系统的研究。使用K 2 CO 3 -DMSO已经实现了3-取代的吡唑的区域选择性N1-烷基化,-芳基化和-杂芳基化。通过在B3LYP / 6-31G **(d)水平上的DFT计算可以证明区域选择性。对于N-烷基吡唑类似物,已经观察到对化学位移的一致的空间效应。已获得二十五个X射线晶体学结构,以确认主要产品的区域化学。