Rapid and eco-friendly high yield synthesis of dihydroquinazolinones mediated by urea/zinc chloride eutectic mixture

2019 ◽  
Vol 14 ◽  
pp. 100167 ◽  
Author(s):  
Diana Peña-Solórzano ◽  
Carlos E. González Guilombo ◽  
Cristian Ochoa-Puentes
2020 ◽  
Vol 44 (19) ◽  
pp. 7987-7997
Author(s):  
Diana Peña-Solórzano ◽  
Vladimir V. Kouznetsov ◽  
Cristian Ochoa-Puentes

An environmentally friendly and efficient method for the synthesis of indeno[2,1-c]quinolines is developed using a urea/zinc chloride eutectic mixture as a green mildly acidic medium.


2006 ◽  
Vol 61 (1) ◽  
pp. 37-46 ◽  
Author(s):  
Constantina Papatriantafyllopoulou ◽  
Catherine P. Raptopoulou ◽  
Aris Terzis ◽  
Evy Manessi-Zoupa ◽  
Spyros P. Perlepes

The reactions of methyl(2-pyridyl)ketone oxime, (py)C(Me)NOH, with zinc chloride have been investigated. An excess of the ligand in EtOH/MeCN affords the mononuclear complex [ZnCl2{(py)C(Me)NOH}2] (1) in moderate yield. The metal ion is coordinated by two chloro ligands and two N,N′- chelating (py)C(Me)NOH molecules. The six-coordinate molecule is the ciscis- trans isomer considering the positions of the coordinated chlorine, pyridyl and oxime nitrogen atoms, respectively. The reaction between equimolar quantities of ZnCl2, (py)C(Me)NOH and LiOH·H2O in EtOH/MeCN leads to the tetranuclear cluster [Zn4(OH)2Cl2{(py)C(Me)NO}4] (2) in high yield. The molecule lies on a crystallographic inversion center and has an inverse 12-metallacrown- 4 topology. Two triply bridging hydroxides are accommodated within the metallacrown ring. Each (py)C(Me)NO− ligand adopts the 2.111 coordination mode (Harris notation), chelating one ZnII ion and bridging a ZnII 2 pair. Two metal ions are in a distorted O2N4 octahedral environment, whereas the other two are in a severely distorted tetrahedral O3Cl environment. Complex 2 joins a small family of structurally characterized zinc(II) metallacrown complexes. The IR data are discussed in terms of the nature of bonding and the structures of the two complexes.


1978 ◽  
Vol 56 (11) ◽  
pp. 1492-1499 ◽  
Author(s):  
Stephen Hanessian ◽  
Robert Massé ◽  
Goran Ekborg

Treatment of penta-N-benzyloxycarbonylparomomycin with benzaldehyde and excess zinc chloride gives a dibenzylidene derivative in high yield. This consists of the 4′,6′-O-benzylidene 4′′′,6′′′-N,O-benzylidene (dihydrooxazine) derivative of penta-N-benzyloxycarbonylparomomycin. Chemical evidence is presented to support this structure and model studies are reported for the formation of dihydrooxazine and oxazolidine derivatives of benzyloxycarbonylamino sugars containing suitably situated hydroxyl groups. The easily obtained dihydrooxazine derivative of paromomycin constitutes an interesting, preferentially blocked derivative, that is useful for the chemical modification of the parent antibiotic.


Synlett ◽  
2018 ◽  
Vol 30 (02) ◽  
pp. 225-229 ◽  
Author(s):  
Cristian Ochoa-Puentes ◽  
Natalia Higuera ◽  
Diana Peña-Solórzano

The low-melting mixture urea–ZnCl2 was evaluated as a novel reaction medium for the synthesis of imidazoles. The reaction between a dicarbonyl compound, ammonium acetate, and an aromatic aldehyde is efficiently catalyzed by the eutectic solvent, yielding a wide variety of triaryl-1H-imidazoles or 2-aryl-1H-phenanthro[9,10-d]imidazoles in good to excellent yields. In addition, the eutectic solvent was reused in five cycles without loss of its catalytic activity. This protocol was further explored for the synthesis of the drug trifenagrel, giving an excellent yield.


2019 ◽  
Vol 7 (22) ◽  
pp. 18630-18639 ◽  
Author(s):  
Angélica Peñaranda Gómez ◽  
Oscar Rodríguez Bejarano ◽  
Vladimir V. Kouznetsov ◽  
Cristian Ochoa-Puentes

Author(s):  
N. Tempel ◽  
M. C. Ledbetter

Carbon films have been a support of choice for high resolution electron microscopy since the introduction of vacuum evaporation of carbon. The desirable qualities of carbon films and methods of producing them has been extensively reviewed. It is difficult to get a high yield of grids by many of these methods, especially if virtually all of the windows must be covered with a tightly bonded, quality film of predictable thickness. We report here a method for producing carbon foils designed to maximize these attributes: 1) coverage of virtually all grid windows, 2) freedom from holes, wrinkles or folds, 3) good adhesion between film and grid, 4) uniformity of film and low noise structure, 5) predictability of film thickness, and 6) reproducibility.Our method utilizes vacuum evaporation of carbon from a fiber onto celloidin film and grid bars, adhesion of the film complex to the grid by carbon-carbon contact, and removal of the celloidin by acetone dissolution. Materials must be of high purity, and cleanliness must be rigorously maintained.


Author(s):  
John A. Sutliff

Near-eutectic Pb-Sn alloys are important solders used by the electronics industry. In these solders, the eutectic mixture, which solidifies last, is the important microstructural consituent. The orientation relation (OR) between the eutectic phases has previously been determined for directionally solidified (DS) eutectic alloys using x-ray diffraction or electron chanelling techniques. In the present investigation the microstructure of a conventionally cast, hyper-eutectic Pb-Sn alloy was examined by transmission electron microscopy (TEM) and the OR between the eutectic phases was determined by electron diffraction. Precipitates of Sn in Pb were also observed and the OR determined. The same OR was found in both the eutectic and precipitation reacted materials. While the precipitation of Sn in Pb was previously shown to occur by a discontinuous precipitation reaction,3 the present work confirms a recent finding that volume diffusion controlled precipitation can also occur.Samples that are representative of the solder's cast microstructure are difficult to prepare for TEM because the alloy is multiphase and the phases are soft.


Author(s):  
Hong-Ming Lin ◽  
C. H. Liu ◽  
R. F. Lee

Polyetheretherketone (PEEK) is a crystallizable thermoplastic used as composite matrix materials in application which requires high yield stress, high toughness, long term high temperature service, and resistance to solvent and radiation. There have been several reports on the crystallization behavior of neat PEEK and of CF/PEEK composite. Other reports discussed the effects of crystallization on the mechanical properties of PEEK and CF/PEEK composites. However, these reports were all concerned with the crystallization or melting processes at or close to atmospheric pressure. Thus, the effects of high pressure on the crystallization of CF/PEEK will be examined in this study.The continuous carbon fiber reinforced PEEK (CF/PEEK) laminate composite with 68 wt.% of fibers was obtained from Imperial Chemical Industry (ICI). For the high pressure experiments, HIP was used to keep these samples under 1000, 1500 or 2000 atm. Then the samples were slowly cooled from 420 °C to 60 °C in the cooling rate about 1 - 2 degree per minute to induce high pressure crystallization. After the high pressure treatment, the samples were scanned in regular DSC to study the crystallinity and the melting temperature. Following the regular polishing, etching, and gold coating of the sample surface, the scanning electron microscope (SEM) was used to image the microstructure of the crystals. Also the samples about 25mmx5mmx3mm were prepared for the 3-point bending tests.


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