16782-08-4Relevant articles and documents
An Anionic, Chelating C(sp3)/NHC ligand from the Combination of an N-heterobicyclic Carbene and Barbituric Heterocycle
Benaissa, Idir,Gajda, Katarzyna,Vendier, Laure,Lugan, No?l,Kajetanowicz, Anna,Grela, Karol,Michelet, Véronique,César, Vincent,Bastin, Stéphanie
, p. 3223 - 3234 (2021/09/30)
The coordination chemistry of the anionic NHC1-based on an imidazo[1,5-a]pyridin-3-ylidene (IPy) platform substituted at the C5 position by an anionic barbituric heterocycle was studied with d6(Ru(II), Mn(I)) and d8(Pd(II), Rh(I), Ir(I), Au(III)) transition-metal centers. While the anionic barbituric heterocycle is planar in the zwitterionic NHC precursor 1·H, NMR spectroscopic analyses supplemented by X-ray diffraction studies evidenced the chelating behavior of ligand 1-through the carbenic and the malonic carbon atoms in all of the complexes, resulting from a deformation of the lateral barbituric heterocycle. The complexes were obtained by reaction of the free carbene with the appropriate metal precursor, except for the Au(III) complex 10, which was obtained by oxidation of the antecedent gold(I) complex [AuCl(1)]?with PhICl2as an external oxidant. During the course of the process, the kinetic gold(I) intermediate 9 resulting from the oxidation of the malonic carbon of the barbituric moiety was isolated upon crystallization from the reaction mixture. The νCOstretching frequencies recorded for complex [Rh(1)(CO)2] (5) demonstrated the strong donating character of the malonate-C(sp3)/NHC ligand 1-. The ruthenium complex [Ru(1)Cl(p-cymene)] (11) was implemented as a precatalyst in the dehydrogenative synthesis of carboxylic acid derivatives from primary alcohols and exhibited high activities at low catalyst loadings (25-250 ppm) and a large tolerance toward functional groups.
Efficient Method for Aromatic-Aldehyde Oxidation by Cleavage of Their Hydrazones Catalysed by Trimethylsilanolate
Burglova, Kristyna,Okorochenkov, Sergei,Budesinsky, Milos,Hlavac, Jan
, p. 389 - 396 (2017/01/24)
The reactions of hydrazones, derived from various aromatic aldehydes bound to Rink resin and hydrazines, with trimethylsilanolate have been studied. In this process, the aldehydes were oxidized to the corresponding carboxylic acids. The reaction was also tested with success in solution, with various aromatic aldehydes easily being oxidized in one pot via hydrazone formation and trimethylsilanolate treatment. A mechanism for the hydrazone cleavage is proposed. The reaction may be used as an alternative method for aldehyde oxidation with the selectivity complementary to that of currently used reactions.
4-HYDROXY BENZOATE DERIVATIVES FOR USE IN THE TREATMENT OF INFECTION, INFLAMMATION OR PAIN
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Page/Page column 13, (2009/01/23)
The invention provides a compound of the general formula (I) for use in the topical treatment of infection, inflammation and/or pain: wherein R1 independently represents a methylene group, an ethylene group or a straight or branched chain C3 to C6 alkylene group; R2 independently represents a hydrogen atom, a methyl group, an ethyl group or a straight or branched chain C3 to C20 alkyl group; x represents 0 or an integer from 1 to 4 and y represents 0 or an integer from 1 to 4, wherein the sum of x and y is 4; and Z represents a hydrogen atom or (HOR1)yR2XN⊕; compositions comprising the compound; use of the compound in the manufacture of a medicament; and methods of medical treatment comprising the topical application of the compound.
Regioselective Carboxylation of Phenols with Carbon Dioxide
Rahim, Mohammad Abdur,Matsui, Yoshihisa,Matsuyama, Takanori,Kosugi, Yoshio
, p. 2191 - 2195 (2007/10/03)
A few novel methods were developed for the regioselective preparation of p-hydroxybenzoic acid (pHBA) and its amino derivative by means of the Kolbe-Schmitt reaction. Thus, the carboxylation of tetraalkylammonium phenoxide at 125°C under the CO2 pressure of 5.0 MPa in the presence of K2CO3 gave pHBA in a maximum yield of 56% with the regioselectivity of 97-100%. The carboxylation of potassium phenoxide (PhOK) at 230°C under the CO2 pressure of 0.5 MPa also gave pHBA regioselectively in a 39% yield, together with unaltered phenol (61%) Under such conditions, the potassium salt of salicylic acid (SA) once formed was transformed into pHBA. Heat treatment of the dipotassium salt of 13C labeled SA indicated that the transformation occurs via two pathways, i.e., the intramolecular rearrangement of the salicylate (66%) and the decarboxylation of the salicylate followed by the recarboxylation of the resulting PhOK (34%). Furthermore, the carboxylation of cesium m-aminophenoxide and 5-amino-1-naphthoxide with CO2 gave regioselectively 4-hydroxyanthranilic and 8-amino-4-hydroxy-1-naphthoic acids, respectively, in good yields. This is a simple one-pot reaction giving these industrially useful acids with good yields.
