644-98-4Relevant academic research and scientific papers
On the metallation of 2-isopropylpyridine
Pasquinet, Eric,Rocca, Patrick,Marsais, Francis,Godard, Alain,Queguiner, Guy
, p. 8771 - 8782 (1998)
2-Isopropylpyridine has been successfully metallated and functionalized by using potassium diisopropylamide (KDA). Subsequent functionalization has been achieved with a wide range of electrophiles and good to excellent yields have been obtained. The action of other potassium or sodium bases has also been investigated.
Photoredox-catalysed regioselective synthesis of C-4-alkylated pyridines with N -(acyloxy)phthalimides
He, Qian,Yang, Chunhao,Zhang, Xiaofei,Zhang, Zhucheng
supporting information, p. 1969 - 1973 (2022/03/15)
A method of direct C-4 selective alkylation of pyridines under visible light irradiation at room temperature has been reported, using simple maleate-derived pyridinium salts as pyridine precursors and the readily available carboxylic acid-derived N-(acyloxy)phthalimides as alkyl radical precursors, affording good to excellent yields without using stoichiometric oxidants and acids. A broad range of primary, secondary, and tertiary carboxylates can be used as alkylation reagents. Oxidant and acid-sensitive functional groups can be tolerated well. This journal is
A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
García-Domínguez, Andrés,Gonzalez, Jorge A.,Leach, Andrew G.,Lloyd-Jones, Guy C.,Nichol, Gary S.,Taylor, Nicholas P.
supporting information, (2022/01/04)
The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R′3-nRnX (X = P, N; R′ = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
Manganese-Catalyzed Kumada Cross-Coupling Reactions of Aliphatic Grignard Reagents with N-Heterocyclic Chlorides
Petel, Brittney E.,Purak, Merjema,Matson, Ellen M.
supporting information, p. 1700 - 1706 (2018/07/13)
Herein we report the use of manganese(II) chloride for the catalytic generation of C(sp 2)-C(sp 3) bonds via Kumada cross-coupling. Rapid and selective formation of 2-alkylated N-heterocyclic complexes were observed in high yields with use of 3 mol% MnCl 2 THF 1.6 and under ambient reaction conditions (21 °C, 15 min to 20 h). Manganese-catalyzed cross-coupling is tolerant toward both electron-donating and electron-withdrawing functional groups in the 5-position of the pyridine ring, with the latter resulting in an increased reaction rate and a decrease in the amount of nucleophile required. The use of this biologically and environmentally benign metal salt as a catalyst for C-C bond formation highlights its potential as a catalyst for the late-stage functionalization of pharmaceutically active N-heterocyclic molecules (e.g., pyridine, pyrazine).
Copper-catalyzed cross-coupling of aryl-, primary alkyl-, and secondary alkylboranes with heteroaryl bromides
Bergmann, Allison M.,Oldham, Adam M.,You, Wei,Brown, M. Kevin
supporting information, p. 5381 - 5384 (2018/06/01)
A method for the Cu-catalyzed cross-coupling of both aryl and alkylboranes with aryl bromides is described. The method employs an inexpensive Cu-catalyst and functions for a variety of heterocyclic as well as electron deficient aryl bromides. In addition, aryl iodides of varying substitution patterns and electronic properties work well.
Synthesis of a Series of Structurally Diverse MB327 Derivatives and Their Affinity Characterization at the Nicotinic Acetylcholine Receptor
Rappenglück, Sebastian,Sichler, Sonja,H?fner, Georg,Wein, Thomas,Niessen, Karin V.,Seeger, Thomas,Paintner, Franz F.,Worek, Franz,Thiermann, Horst,Wanner, Klaus T.
supporting information, p. 1806 - 1816 (2018/09/11)
A novel series of 30 symmetric bispyridinium and related N-heteroaromatic bisquaternary salts with a propane-1,3-diyl linker was synthesized and characterized for their binding affinity at the MB327 binding site of nicotinic acetylcholine receptor (nAChR) from Torpedo californica. Compounds targeting this binding site are of particular interest for research into new antidotes against organophosphate poisoning, as therapeutically active 4-tert-butyl-substituted bispyridinium salt MB327 was previously identified as a nAChR re-sensitizer. Efficient access to the target compounds was provided by newly developed methods enabling N-alkylation of sterically hindered or electronically deactivated heterocycles exhibiting a wide variety of functional groups. Determination of binding affinities toward the MB327 binding site at the nAChR, using a recently developed mass spectrometry (MS)-based Binding Assay, revealed that several compounds reached affinities similar to that of MB327 (pKi=4.73±0.03). Notably, the newly prepared lipophilic 4-tert-butyl-3-phenyl-substituted bispyridinium salt PTM0022 (3 h) was found to have significantly higher binding affinity, with a pKi value of 5.16±0.07, thus representing considerable progress toward the development of more potent nAChR re-sensitizers.
Iron-Catalyzed Isopropylation of Electron-Deficient Aryl and Heteroaryl Chlorides
Sanderson, James N.,Dominey, Andrew P.,Percy, Jonathan M.
, p. 1007 - 1017 (2017/03/27)
Traditional methods for the preparation of secondary alkyl-substituted aryl and heteroaryl chlorides challenge both selectivity and functional group tolerance. This contribution describes the use of statistical design of experiments to develop an effective procedure for the preparation of isopropyl-substituted (hetero)arenes with minimal isopropyl to n-propyl isomerization. The reaction tolerates electronically diverse aryl chloride coupling partners, with excellent conversion observed for strongly electron-deficient aromatic rings, such as esters and amides. Electron-rich systems, including methyl- and methoxy-substituted aryl chlorides, were found to be less reactive. Furthermore, the reaction was found to be most successful when heteroaryl chlorides were submitted to the cross-coupling protocol. By mapping substituent effects on reaction selectivity, we were able to show that electron-deficient aryl chlorides are essential for efficient coupling, and use electronic structure calculations to predict the likelihood of successful coupling through the estimation of the electron affinity of each aryl chloride. Moderate isolated yields were achieved with selected aryl chlorides, and moderate to good isolated yields were obtained for all the heteroaryl chlorides coupled. Excellent selectivity was observed when a 2,6-dichloroquinoline was used, allowing mono-substitution on a challenging substrate. (Figure presented.).
Magnesiation of N-Heterocycles Using i-PrMgCl · LiCl and catalytic diisopropylamine
Nxumalo,Dinsmore
supporting information, p. 2478 - 2484 (2015/11/10)
The direct magnesiation of various N-heterocyclic compounds with i-PrMgCl · LiCl and catalytic diisopropylamine allows for preparation of 2-substituted pyrroles, imidazole, indoles, and benzimidazoles, in moderate to good yields. The magnesiated substrates canreadily undergo a Kumada-type coupling with iodo-aryls in the presence of catalytic Pd(PPh3)4.
Asymmetric Hydrogenation of Pyridinium Salts with an Iridium Phosphole Catalyst
Chang, Mingxin,Huang, Yuhua,Liu, Shaodong,Chen, Yonggang,Krska, Shane W.,Davies, Ian W.,Zhang, Xumu
supporting information, p. 12761 - 12764 (2016/02/18)
Iridium-catalyzed asymmetric hydrogenation of N-alkyl-2-alkylpyridinium salts provided 2-aryl-substituted piperidines with high levels of enantioselectivity. Simple benzyl and other alkyl groups successfully activated the challenging pyridine substrates toward hydrogenation. The use of the unusual chiral-phosphole-based MP2-SEGPHOS was the key to the success of this approach which provides a versatile and practical procedure for the synthesis of chiral piperidines. Ring to ring: Simple N-benzyl and N-alkyl groups successfully activated pyridine substrates toward hydrogenation. The use of the unusual chiral phosphole-based ligand L was the key to the success of this approach, which provides a versatile and practical procedure for the synthesis of chiral piperidines. cod=1,5-cyclooctadiene.
Bis(phosphine)cobalt dialkyl complexes for directed catalytic alkene hydrogenation
Friedfeld, Max R.,Margulieux, Grant W.,Schaefer, Brian A.,Chirik, Paul J.
supporting information, p. 13178 - 13181 (2015/03/30)
Planar, low-spin cobalt(II) dialkyl complexes bearing bidentate phosphine ligands, (P - P)Co-(CH2SiMe3)2, are active for the hydrogenation of geminal and 1,2-disubstituted alkenes. Hydrogenation of more hindered internal and endocyclic trisubstituted alkenes was achieved through hydroxyl group activation, an approach that also enables directed hydrogenations to yield contrasteric isomers of cyclic alkanes.
