Search results for "Thiourea"
showing 10 items of 96 documents
Study of peak shape and efficiency in butyl acrylate-based monolithic columns for capillary electrochromatography.
2009
Abstract The study and modelling peak shape of in capillary electrochromatography (CEC), obtained using butyl acrylate (BA)-based monolithic columns, is described in this article. A modified-Gaussian model, which is a function of conventional experimental parameters: retention time (tR), peak height (H0) and standard deviation (σ0) at the peak maximum, and left (A) and right (B) halfwidths, was used to describe the peaks of thiourea and several polyaromatic hydrocarbons compounds, which were eluted under several applied voltages. A mean relative error below 2% in the prediction of peak shape is obtained. Based on peak parameters, an easy and reliable estimation of global chromatographic per…
Solid–liquid extraction of ω-amino acids using ditopic receptors
2008
Abstract Five heteroditopic ligands have been prepared to be used in solid–liquid extraction of ω-amino acids into DMSO solutions. The prepared ligands contain crown ethers as cation binding sites and thiourea or amide groups for anion recognition. The aliphatic zone of the 1H NMR spectra suggests that two different species related to the amino acid are present in solution. One of these species is the complexed zwitterionic form and the other seems to be free non-zwitterionic amino acid. The presence of these two species allows extraction efficiencies higher than 100%.
ChemInform Abstract: Organocatalytic Enantioselective Synthesis of Pyrazoles Bearing a Quaternary Stereocenter.
2016
An efficient one-pot asymmetric synthesis of pyrazoles bearing a chiral quaternary stereocenter has been developed. Quinine-derived thiourea catalyzed the enantioselective addition of pyrazolones to isatin-derived ketimines, providing the corresponding acetylated pyrazoles after in situ treatment with Ac2 O/Et3 N. The corresponding pyrazoles were afforded in high yields and excellent enantioselectivities.
Fluorescent chemosensors based on cyclohexane: selective sensing of succinate and malonate versus their longer or shorter homologues
2008
The sensing properties towards aliphatic α,ω-dicarboxylates of five cyclohexane-based ligands are described. The studied ligands have been designed following the binding site-signalling unit approach and they all possess thiourea groups as recognition moieties. Ligands 1 and 3 containing naphthalene units can be used as fluorescent sensors as they form intra- or intermolecular excimers in the presence of appropriate dicarboxylates. Selective sensing of succinate and malonate versus their longer or shorter homologues has been observed.
H2-Antihistaminica, 1. Mitt.: 2-Substituierte 4-[[2-(N′-Methyl-thioureido)-äthylmercapto]-methyl]-imidazole
1976
Es wird die Synthese der 2-substituierten 4-[[2-(N′-Methylthioureido)-athylmercapto]-methyl]-imidazole 5a–f als potentielle H2-Antihistaminica beschrieben. Ausgehend von den Imidazol-4-carbinolen 3a–f lassen sich die 2-substituierten 4-[(2-Amino-athylmercapto)-methyl]-imidazole 4a–f durch saurekatalysierte Reaktion mit Cysteamin darstellen und mit Methylisothiocyanat in die entsprechenden Thioharnstoffderivate 5 uberfuhren. 2-Substituted 4-[[2-(N′-Methyl-thioureido)-ethylmercapto]-methyl]-imidazoles The synthesis of 2-substituted 4-[[2-(Ns′-methyl-thioureido)-ethylmercapto]-methyl]-imidazoles 5a–f, as potential H2-antihistaminics, is described. The acid catalyzed reaction of the imidazole-4…
Regioselective Synthesis of 2-Imino-1,3-thiazolidin-4-ones by Treatment ofN-(Anthracen-9-yl)-N′-ethylthiourea with Bromoacetic Acid Derivatives
2002
The reaction between N-(anthracen-9-yl)-N′-ethylthiourea (1) and methyl bromoacetate yielded mainly 2-[(anthracen-9-yl)imino]-3-ethyl-1,3-thiazolidin-4-one (2), together with some of the regioisomeric 3-(anthracen-9-yl)-2-ethylimino-1,3-thiazolidin-4-one (3). The structures of the products were elucidated by NMR techniques and, for 3, X-ray crystallographic analysis. Treatment of 1 with bromoacetyl bromide again yielded 2 and 3, but with a reversed product distribution ratio, thus providing an interesting and unexpected regioselectivity, depending on the electrophile selected. The underlying cause of the observed regioselectivity is a result of different reaction pathways taken by the two e…
ChemInform Abstract: Cooperative Assistance in Bifunctional Organocatalysis: Enantioselective Mannich Reactions with Aliphatic and Aromatic Imines.
2013
both of which contain a thiourea moiety (Scheme 1).The catalysts are capable of deprotonating suitable nucleo-philes, such as activated carbonyl compounds. This proton-transfer reaction generates an ion pair, which is composed ofthe protonated catalyst and the anionic nucleophile interact-ing through hydrogen bonds. At least one of the NH moietiesin the protonated catalyst is involved in activating theelectrophilic reaction partner.
H2-Antihistaminika, 6. Mitt. Synthese und Wirkung N-substituierter 4-[(2-Amino-ethylmercapto)-methyl]-imidazole
1980
Es wurden die N-substituierten 4-[(2-Amino-ethylmercapto)-methyl]-imidazole 2 und 3 dargestellt und auf histaminartige Wirkung untersucht. Die Thioharnstoff- und Cyanoguanidin-Derivate von 3b zeigten keine H2-antihistaminische Wirksamkeit. H2-Antihistaminics, VI: Synthesis and Activity of N-Substituted 4-[(2-Aminoethylmercapto)methyl]imidazoles The N-substituted 4-[(2-aminoethylmercapto)methyl]imidazoles 2 and 3 were prepared and tested for their histamine-like activity. The thiourea and cyanoguanidine derivatives of 3b showed no H2-antihistaminic activity.
ChemInform Abstract: Organocatalytic Asymmetric Addition of Naphthols and Electron-Rich Phenols to Isatin-Derived Ketimines: Highly Enantioselective …
2015
A quinine-derived thiourea organocatalyst promoted the highly enantioselective addition of naphthols and activated phenols to ketimines derived from isatins. The reaction afforded chiral 3-amino-2-oxindoles with a quaternary stereocenter in high yields (up to 99 %) with excellent enantioselectivity (up to 99 % ee). To the best of our knowledge, this transformation is the first highly enantioselective addition of naphthols to ketimines.
Herbicidal Derivatives of Aminomethylenebisphosphonic Acid. Part IV. Hydroxyalkylidenebisphosphonates, Iminomethylenebisphosphonates and Ureidomethyl…
2000
Derivatives of aminomethylenebisphosphonic acids constitute a class of promising herbicides. Replacement of the amino group by hydroxyl, ureido, thioureido, or imino moieties leads to compounds of significant herbicidal properties. This indicates that protonated amino function is not a requirement for phytotoxic action of bisphosphonates.