The Re(I) coordination chemistry of a series of pyrido[2,3-b]pyrazine-derived ligands: Syntheses, characterisation and crystal structures
摘要:
Reaction of 2,3-diaminopyridine with one equivalent of a functionalised vicinal diketone, in ethanol, yields a series of ligands based upon the pyrido[2,3-b]pyrazine core. The ligands were characterised by (1)H, (13)C-{(1)H} NMR, MS and UV-Vis spectroscopy. Reaction of the ligands with one equivalent of (ReBr(CO)(5)) gave a series of Re-L(n) complexes based upon the general formula fac-[ReBr(CO)(3)(L)] (where L = pyrido[2,3-b]pyrazine-derived ligands, L(1)-L(6)). Solution IR studies confirmed the retention of the facially capped, tri-carbonyl coordination geometry at rhenium, and (1)H NMR studies confirmed coordination of the ligand to Re(I). El HR MS data were obtained for each complex confirming the proposed formulation and stoichiometry. Single crystal X-ray structures were obtained for three of the complexes (Re-L(1), Re-L(2), Re-L(6)), with each demonstrating that the ligands coordinate to Re([) in a bidentate manner, via a four-membered chelate ring, which was unsymmetrical in the former two cases. The electronic absorption spectra of the complexes showed absorption into the visible region ca. 375-500 nm, (the complexes are orange-red in appearance). Following irradiation at 350-450 nm, the complexes display a solid-state broad emission peaking between 600-700 nm. The complexes were not sufficiently luminescent in solution to allow further investigation into the origin of this emission band, although with reference to related 1,8-naphthyridine complexes of Re(I) it is likely to incorporate significant (3)MLCT character. (C) 2009 Elsevier Ltd. All rights reserved.
bis(indolyl)methanes was developed using 3,5-bis(trifluoromethyl) phenyl ammonium hexafluorophosphate (BFPHP) as a novel organocatalyst. MATERIALS AND METHODS All of the obtained products are known compounds and identified by IR, 1HNMR, 13CNMR and melting points. RESULT Various products were obtained in good to excellent yields under reaction conditions. CONCLUSION The BFPHP organocatalyst demonstrates a novel class
A general and inexpensive protocol for the nanomagnetic 5-sulfosalicylic acid catalyzed the synthesis of tetrahydrobenzo[b]pyrans and quinoxaline derivatives
Fe3O4@SiO2@5-SA (20 mg) showed excellent reactivity for greener synthesis of tetrahydrobenzo[b]pyrans via a three-component reaction of different aromatic aldehydes, malononitrile and dimedone in good to excellent yields (70–95%) in pure water at short reaction times (40–150 min). The method shows eco-friendly synthesis of quinoxaline derivatives from direct condensation of substituted 1,2-diamine with various
在这项研究中,通过将水溶性5-磺基水杨酸锚定在表面二氧化硅改性的Fe 3 O 4上,制备了具有高负载多功能酸性基团的新型酸官能化磁性纳米粒子。磁性可循环利用的Fe 3 O 4 @SiO 2@ 5-SA(20毫克)显示出不同的芳香性醛,丙二腈和二甲酮的三组分反应,可在较短的时间里纯净水中获得良好至优异的收率(70-95%),从而对绿色四氢苯并[b]吡喃的合成具有优异的反应性。反应时间(40–150分钟)。该方法表明,在室温下,乙醇中的取代的1,2-二胺与各种1,2-二羰基直接缩合,可以生态友好地合成喹喔啉衍生物,从而在较短的时间内即可获得所需的喹喔啉,并具有良好或优异的收率(60-97%)反应时间(120–240分钟)。用扫描电子显微镜,X射线粉末衍射,傅立叶平移红外光谱,振动样品磁强计和热重分析法研究了MNP的形态和磁性。结果表明,Fe 3 O4 @SiO 2 @ 5-SA催化剂可通过外部
An Efficient and Green Procedure for the Synthesis of Quinoxaline Derivatives using 3,5-Bis(trifluoromethyl)phenylammonium triflate (BFPAT) Organocatalyst
The application of 3,5-bis(trifluoromethyl)phenylammonium triflate (BFPAT) as a convenient new organocatalyst for the synthesis of quinoxaline derivatives is described. In the presence of BFPAT, one-pot synthesis of a wide variety of quinoxaline derivatives was achieved by the reaction of various o-phenylenediamines and 1,2-dicarbonyl compounds in water.
A Novel One-Pot Synthesis of Quinoxaline Derivatives in Fluorinated Alcohols
作者:Samad Khaksar、Fariba Rostamnezhad
DOI:10.5012/bkcs.2012.33.8.2581
日期:2012.8.20
Hexafluoroisopropanol (HFIP) is explored as an effective medium for the synthesis of quinoxaline derivatives in high yields at room temperature. The solvent (HFIP) can be readily separated from reaction products and recovered in excellent purity for direct reuse.
Pentafluorophenylammonium triflate: A highly efficient catalyst for the synthesis of quinoxaline derivatives in water
作者:Samad Khaksar、Hanieh Radpeyma
DOI:10.1016/j.crci.2013.11.009
日期:2014.10
Résumé A simple, inexpensive, environmentally friendly and efficient route for the rapid and efficient synthesis of quinoxaline derivatives using pentafluorophenylammonium triflate (PFPAT) as a catalyst is described. Various quinoxaline derivatives were synthesized in good to excellent yields. The preparation of PFPAT catalyst from simple and readily available starting materials makes this method more affordable.