120-94-5Relevant articles and documents
The 4-[N-methyl-N-(2,2,2-trifiuoroacetyl)amino]butyl group as an alternative to the 2-cyanoethyl group for phosphate protection in the synthesis of oligodeoxyribonucleotides
Wilk, Andrzej,Grajkowski, Andrzej,Phillips, Lawrence R.,Beaucage, Serge L.
, p. 7515 - 7522 (1999)
The 4-[N-methyl-N-(2,2,2-trifluoroacetyl)amino]butyl group for phosphate protection in the synthesis of oligodeoxyribonucleotides has been developed to completely prevent nucleobase alkylation by acrylonitrile that could potentially occur upon deprotection of the traditional 2-cyanoethyl phosphate protecting group. The properties of this new phosphate protecting group were evaluated using the model phosphotriester 9. The mechanism of phosphate deprotection was studied by treating 9 with concentrated NH4OH. NMR analysis of the deprotection reaction demonstrated that cleavage of the N- trifiuoroacetyl group is rate-limiting. The resulting phosphotriester intermediate 13 was also shown to undergo rapid cyclodeesterification to produce O,O-diethyl phosphate 15 and N-methylpyrrolidine 16 (Scheme 2). Given the facile removal of the 4-[N-methyl-N-(2,2,2-trifluoroacetyl)amino]butyl phosphate protecting group under mild basic conditions, its utilization in oligonucleotide synthesis began with the preparation of the deoxyribonucleoside phosphoramidites 4a-d (Scheme 3). The coupling efficiency of 4a-d and conventional 2-cyanoethyl deoxyribonucleoside phosphoramidites 24a-d was then compared in the solid-phase synthesis of the 20-met d(ATCCGTAGCTAAGGTCATGC). As previously observed in the deprotection of 9, the 4-[N-methyl,N-(2,2,2-trifluoroacetyl)amino]butyl phosphate protecting groups were easily and completely removed from the oligonucleotide by using either concentrated NH4OH or pressurized ammonia gas. Analysis of the deprotected oligomer by polyacrylamide gel electrophoresis (Figure 3) indicated that the phosphoramidites 4a-d are as efficient as the 2-cyanoethyl phosphoramidites 24a-d in the synthesis of the 20-mer. Furthermore, following digestion of the crude 20-met by snake venom phosphodiesterase and bacterial alkaline phosphatase, HPLC analysis showed complete hydrolysis to individual nucleosides and no detectable nucleobase modification.
Gas-Phase Elimination Kinetics of (Dimethylamino)alkyl Acetates. The Ion-Pair Mechanism through Neighboring Group Participation.
Chuchani, Gabriel,Rotinov, Alexandra,Dominguez, Rosa M.,Gonzalez, Neil
, p. 4157 - 4160 (1984)
The gas-phase elimination kinetics of some amino esters and a keto acetate have been studied in the temperature region of 260.0-411.5 deg C and in the pressure range of 21.5-170.0 torr.These eliminations, in vessels seasoned with allyl bromide, are predominantly unimolecular and homogenous and obey a first order rate law.The rate coefficients for the reactions are expressible by the following Arrhenius equations: for 3-(dimethylamino)-1-propyl acetate (1), log k1 (s-1) = (12.97 +/- 0.20) - (202.1 +/- 2.5) kJ mol-1 (2.303RT)-1; for 4-(dimethylamino)-1-butyl acetate (4), log k1 (s-1) = (11.91 +/- 0.43) - (163.5 +/- 4.8) kJ mol-1 (2.303 RT)-1; for 4-oxo-1-pentyl acetate (7), log k1 (s-1) = (12.77 +/- 0.36) - (202.8 +/- 4.6) kJ mol-1 (2.303RT)-1.The presence of the (CH3)2N group in these acetates appears to provide anchimeric assistance in the elimination; methyl acetate and the corresponding heterocyclic products arise from an intimate ion-pair mechanism.The CH3CO substituent is believed to influence the pyrolysis rate of 5-acetoxy-2-pentanone by a weak steric acceleration.
One-pot synthesis of: N -methylpyrrolidine (NMPD) using Cu- and Ni-modified ZSM-5 as an efficient catalyst
Long, Yan,Wang, Peixue,Fei, Yuqing,Zhou, Dawei,Liu, Shimin,Deng, Youquan
, p. 141 - 148 (2019)
In this study, a green, efficient and low-cost process for the synthesis of N-methylpyrrolidine (NMPD) from 1,4-butanediol (BDO) and methylamine (MA) via a one-pot method was developed. Under the optimized reaction conditions, more than 90% yield of NMPD was achieved over a Cu and Ni modified ZSM-5 catalyst. The catalyst could be reused for several runs retaining a satisfactory catalytic performance, and the scale-up operation showed the potential of industrial application. Characterizations of BET, XPS, XRD, TEM, SEM, H2-TPR and NH3-TPD were conducted for the developed composite catalyst, which suggested that Cu2O and NiO were the main species on the support. Meanwhile, it was found that the H2 atmosphere, the high dispersion of metal oxides and the synergic effect between Cu and Ni species on ZSM-5 contributed to the excellent catalytic performance. Furthermore, a possible mechanism based on a borrowing-hydrogen process was also proposed.
Poisoning and Reuse of Supported Precious Metal Catalysts in the Hydrogenation of N-Heterocycles Part?I: Ruthenium-Catalysed Hydrogenation of 1-Methylpyrrole
Heged?s, László,Sz?ke-Molnár, Kristóf,Sajó, István E.,Srankó, Dávid Ferenc,Schay, Zoltán
, p. 1939 - 1950 (2018)
Abstract: Poisoning phenomena of heterogeneous, supported precious metal catalysts caused by nitrogen were investigated in the liquid-phase hydrogenation of 1-methylpyrrole (MP) to 1-methylpyrrolidine (MPD) over ruthenium on carbon, in non-acidic medium (methanol), at 10?bar and 25–60?°C. Reusing a spent, unregenerated 5% Ru/C catalyst, it was found that the activity of catalyst and the conversion of model substrate were strongly dependent on the amount of catalyst and the number of recycling, respectively. During the first reuse of this ruthenium catalyst, surprisingly, it showed high activity already at room temperature contrary to the fresh catalyst which worked at only 60?°C. This unexpected catalytic behaviour was studied by XRD and XPS methods which revealed the existence of a fine RuO2 layer on the surface of the catalytic metal in the fresh catalyst. Graphical Abstract: [Figure not available: see fulltext.].
Powering Artificial Enzymatic Cascades with Electrical Energy
Al-Shameri, Ammar,Apfel, Ulf-Peter,Lauterbach, Lars,Nestl, Bettina M.,Petrich, Marie-Christine,junge Puring, Kai
, p. 10929 - 10933 (2020)
We have developed a scalable platform that employs electrolysis for an in vitro synthetic enzymatic cascade in a continuous flow reactor. Both H2 and O2 were produced by electrolysis and transferred through a gas-permeable membrane into the flow system. The membrane enabled the separation of the electrolyte from the biocatalysts in the flow system, where H2 and O2 served as electron mediators for the biocatalysts. We demonstrate the production of methylated N-heterocycles from diamines with up to 99 percent product formation as well as excellent regioselective labeling with stable isotopes. Our platform can be applied for a broad panel of oxidoreductases to exploit electrical energy for the synthesis of fine chemicals.
Preparation and GC-MS-Identification of N-Methyl-Δ3-pyrroline
Mahboobi, Siavosh,Fischer, Erich Chr.,Eibler, Ernst,Wiegrebe, Wolfgang
, p. 423 - 424 (1988)
The preparation of N-methyl-Δ3-pyrroline by 1) reduction of N-methyl-pyrrole followed by gc-separation or by 2) condensation of cis-1,4-dichloro-2-butene with methylamine is described.The title compound is identified by GC-MS.
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.
Electrochemical Activation of Diverse Conventional Photoredox Catalysts Induces Potent Photoreductant Activity**
Chernowsky, Colleen P.,Chmiel, Alyah F.,Wickens, Zachary K.
supporting information, p. 21418 - 21425 (2021/08/25)
Herein, we disclose that electrochemical stimulation induces new photocatalytic activity from a range of structurally diverse conventional photocatalysts. These studies uncover a new electron-primed photoredox catalyst capable of promoting the reductive cleavage of strong C(sp2)?N and C(sp2)?O bonds. We illustrate several examples of the synthetic utility of these deeply reducing but otherwise safe and mild catalytic conditions. Finally, we employ electrochemical current measurements to perform a reaction progress kinetic analysis. This technique reveals that the improved activity of this new system is a consequence of an enhanced catalyst stability profile.
Zirconium-hydride-catalyzed site-selective hydroboration of amides for the synthesis of amines: Mechanism, scope, and application
Han, Bo,Jiao, Haijun,Wu, Lipeng,Zhang, Jiong
, p. 2059 - 2067 (2021/09/02)
Developing mild and efficient catalytic methods for the selective synthesis of amines is a longstanding research objective. In this respect, catalytic deoxygenative amide reduction has proven to be promising but challenging, as this approach necessitates selective C–O bond cleavage. Herein, we report the selective hydroboration of primary, secondary, and tertiary amides at room temperature catalyzed by an earth-abundant-metal catalyst, Zr-H, for accessing diverse amines. Various readily reducible functional groups, such as esters, alkynes, and alkenes, were well tolerated. Furthermore, the methodology was extended to the synthesis of bio- and drug-derived amines. Detailed mechanistic studies revealed a reaction pathway entailing aldehyde and amido complex formation via an unusual C–N bond cleavage-reformation process, followed by C–O bond cleavage.
Highly economical and direct amination of sp3carbon using low-cost nickel pincer catalyst
Brandt, Andrew,Rangumagar, Ambar B.,Szwedo, Peter,Wayland, Hunter A.,Parnell, Charlette M.,Munshi, Pradip,Ghosh, Anindya
, p. 1862 - 1874 (2021/01/20)
Developing more efficient routes to achieve C-N bond coupling is of great importance to industries ranging from products in pharmaceuticals and fertilizers to biomedical technologies and next-generation electroactive materials. Over the past decade, improvements in catalyst design have moved synthesis away from expensive metals to newer inexpensive C-N cross-coupling approaches via direct amine alkylation. For the first time, we report the use of an amide-based nickel pincer catalyst (1) for direct alkylation of amines via activation of sp3 C-H bonds. The reaction was accomplished using a 0.2 mol% catalyst and no additional activating agents other than the base. Upon optimization, it was determined that the ideal reaction conditions involved solvent dimethyl sulfoxide at 110 °C for 3 h. The catalyst demonstrated excellent reactivity in the formation of various imines, intramolecularly cyclized amines, and substituted amines with a turnover number (TON) as high as 183. Depending on the base used for the reaction and the starting amines, the catalyst demonstrated high selectivity towards the product formation. The exploration into the mechanism and kinetics of the reaction pathway suggested the C-H activation as the rate-limiting step, with the reaction second-order overall, holding first-order behavior towards the catalyst and toluene substrate.
