2423-65-6Relevant articles and documents
Green Oxidation Process in the Synthesis of LLM-105 with H2O2/Peroxotungstate System and its Theoretical Study
Zhu, Jie,Zhao, Xue-Jing,Wang, Peng-Cheng,Lu, Ming
, p. 1386 - 1394 (2016)
A new catalytic system was developed and applied to the oxidation reactions involved in the synthesis of LLM-105, in which protonated peroxotungstate combining chitosan was used as catalyst. With H2O2as oxidant, good to excellent yields could be achieved in the synthesis of pyrazine-1-oxide, 2,6-dimethoxypyrazine-1-oxide, 2,6-dichloropyrazine-1-oxide, and 2-chloro-6-methoxypyrazine-1-oxide without any addition of trifluoracetic acid, which provided a significant exploration toward novel and environmentally benign synthetic route for LLM-105. Theoretical studies were also carried out with Gaussian 03 to evaluate the oxidation process. All of the calculated data matched well with our experimental results.
C2-Selective, Functional-Group-Divergent Amination of Pyrimidines by Enthalpy-Controlled Nucleophilic Functionalization
Ham, Won Seok,Choi, Hoonchul,Zhang, Jianbo,Kim, Dongwook,Chang, Sukbok
supporting information, p. 2885 - 2892 (2022/02/23)
Synthesis of heteroaryl amines has been an important topic in organic chemistry because of their importance in small-molecule discovery. In particular, 2-Aminopyrimidines represent a highly privileged structural motif that is prevalent in bioactive molecules, but a general strategy to introduce the pyrimidine C2-N bonds via direct functionalization is elusive. Here we describe a synthetic platform for site-selective C-H functionalization that affords pyrimidinyl iminium salt intermediates, which then can be transformed into various amine products in situ. Mechanism-based reagent design allowed for the C2-selective amination of pyrimidines, opening the new scope of site-selective heteroaryl C-H functionalization. Our method is compatible with a broad range of pyrimidines with sensitive functional groups and can access complex aminopyrimidines with high selectivity.
A Biocatalytic Synthesis of Heteroaromatic N-Oxides by Whole Cells of Escherichia coli Expressing the Multicomponent, Soluble Di-Iron Monooxygenase (SDIMO) PmlABCDEF
Petkevi?ius, Vytautas,Vaitekūnas, Justas,Taurait?, Daiva,Stankevi?iūt?, Jonita,?arlauskas, Jonas,??nas, Narimantas,Me?kys, Rolandas
supporting information, p. 2456 - 2465 (2019/01/25)
Aromatic N-oxides (ArN?OX) are desirable biologically active compounds with a potential for application in pharmacy and agriculture industries. As biocatalysis is making a great impact in organic synthesis, there is still a lack of efficient and convenient enzyme-based techniques for the production of aromatic N-oxides. In this study, a recombinant soluble di-iron monooxygenase (SDIMO) PmlABCDEF overexpressed in Escherichia coli was showed to produce various aromatic N-oxides. Out of 98 tested N-heterocycles, seventy were converted to the corresponding N-oxides without any side oxidation products. This whole-cell biocatalyst showed a high activity towards pyridines, pyrazines, and pyrimidines. It was also capable of oxidizing bulky N-heterocycles with two or even three aromatic rings. Being entirely biocatalytic, our approach provides an environmentally friendly and mild method for the production of aromatic N-oxides avoiding the use of strong oxidants, organometallic catalysts, undesirable solvents, or other environment unfriendly reagents. (Figure presented.).
Strategic Approach on N-Oxides in Gold Catalysis – A Case Study
Schie?l, Jasmin,Stein, Philipp M.,Stirn, Judith,Emler, Kirsten,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
supporting information, p. 725 - 738 (2018/10/20)
An extensive kinetic study of selected key reactions of (oxidative) gold catalysis concentrates on the decrease of the catalytic activity due to inhibition of the gold(I) catalyst caused by pyridine derivatives that are obtained as by-products if N-oxides are applied as oxygen donors. The choice of the examined pyridine derivatives and their corresponding N-oxides has been made regardless of their commercial availability; particular attention has been paid to the practical benefit which up to now has been neglected in most of the reaction screenings. The test reactions were monitored by GC and 1H NMR spectroscopy. The received reaction constants provide information concerning a correlation between the electronic structure of the heterocycle and the catalytic activity. Based on the collected kinetic data, it was possible to develop a basic set of three N-oxides which have to be taken into account in further oxidative gold(I)-catalyzed reactions. (Figure presented.).
Pd-Catalyzed Direct C-H Alkenylation and Allylation of Azine N -Oxides
Roudesly, Fares,Veiros, Luis F.,Oble, Julie,Poli, Giovanni
supporting information, p. 2346 - 2350 (2018/04/30)
A Pd-catalyzed direct C2-alkenylation of azine N-oxides with allyl acetate is disclosed. The products are formed through an allylation/isomerization cascade process. The use of a tri-tert-butylphosphonium salt as the ligand precursor and KF is mandatory for optimal yields. When cinnamyl acetate is used, the same catalytic system promotes C2-cinnamylation of the azine N-oxide without subsequent isomerization. A mechanism is proposed on the basis of experimental studies and DFT calculations.
Synthesis of N,N-Dioxopyridazines
Rozen, Shlomo,Shaffer, Avshalom
supporting information, p. 4707 - 4709 (2017/09/23)
Despite many efforts, one of the smallest heterocycles containing two nitrogen atoms, pyridazine, could not be converted to its N,N-dioxide (see, however, Nakadate et al. Chem. Pharm. Bull. 1970, 18, 1211-1218). HOF·CH3CN, made easily from diluted fluorine, was able to accomplish this task in a fast reaction with good yields.
Visible-Light-Induced C2 Alkylation of Pyridine N-Oxides
Zhang, Wen-Man,Dai, Jian-Jun,Xu, Jun,Xu, Hua-Jian
, p. 2059 - 2066 (2017/02/26)
A photoredox catalytic method has been developed for the direct C2 alkylation of pyridine N-oxides. This reaction is compatible with a range of synthetically relevant functional groups for providing efficient synthesis of a variety of C2-alkylated pyridine N-oxides under mild conditions. Mechanistic studies are consistent with the generation of a radical intermediate along the reaction pathway.
Stabilizing volatile liquid chemicals using co-crystallization
Aaker?y, Christer B.,Wijethunga, Tharanga K.,Benton, Joshua,Desper, John
supporting information, p. 2425 - 2428 (2015/02/05)
A convenient, effective, and scalable protocol for stabilizing volatile liquid chemicals is reported. Through the use of halogen-bond driven co-crystal synthesis, several examples of liquid iodoperfluoroalkanes are transformed into crystalline materials with low-vapor pressure, considerable thermal stability, and moisture resistance. The target compounds can subsequently be re-generated through simple solvent-extractions.
Ranking relative hydrogen-bond strengths in hydroxybenzoic acids for crystal-engineering purposes
Aakeroey, Christer B.,Epa, Kanishka,Forbes, Safiyyah,Schultheiss, Nathan,Desper, John
, p. 14998 - 15003 (2013/11/06)
Systematic co-crystallizations resulting in a total of six new crystal structures involving either 3-hydroxy- or 4-hydroxybenzoic acid, complemented by calculated molecular electrostatic potential surfaces and existing structural data, have shown that in a competitive molecular recognition situation, the -OH moiety is a more effective hydrogen-bond donor than the -COOH moiety which, in turn, highlights that electrostatic charge can offer more useful guidance than acidity for predicting competitive hydrogen-bond preferences.
Experimental and theoretical molecular and electronic structures of the N-oxides of pyridazine, pyrimidine and pyrazine
Aitken, R. Alan,Fodi, Bernd,Palmer, Michael H.,Slawin, Alexandra M.Z.,Yang, Jing
experimental part, p. 5845 - 5851 (2012/09/08)
The structures of pyridazine N-oxide, pyrimidine N-oxide and pyrazine N-oxide have been determined by X-ray diffraction for the first time. Comparison with theoretical predictions of the equilibrium structures using the B3LYP method together with a cc-pVTZ basis set, show close agreement with the structural parameters observed, and experimental dipole moments, which suggests that the charge distribution is realistic. An 'atoms in molecules' (AIM) analysis of the computed wave-functions shows total electron densities rather different from the classical picture of a dative bond, whereas the same wave-functions subjected to Mulliken analysis show a more conventional view of the electron distribution. This latter procedure allows a bond dipole analysis of the N-oxide charge distribution.
