288-42-6Relevant articles and documents
Gold(I)-catalyzed protodecarboxylation of (Hetero)aromatic carboxylic acids
Dupuy, Stéphanie,Nolan, Steven P.
supporting information, p. 14034 - 14038 (2013/11/19)
Readily available, inexpensive and easy to handle, carboxylic acids have been shown to be very effective, greener coupling partners compared to costly organometallic reagents for the formation of C-C bonds. The use of well-defined gold complexes furnished 3 in slightly better yield with butyric acid, and in quantitative yield with adamantane-1-carboxylic acid. All reactions reached completion within 16 h. As with silver systems, this reactivity trend highlights, as previously observed, the benefits of potential coordinating groups in the ortho position to the gold binding site, which possibly facilitate the decarboxylation step. Additional reaction time and increased temperatures were necessary to afford the gold aryl products in satisfactory yields. Yet, some substrates such as 2-nitrobenzoic acids reacted poorly and could only be transformed in 50% yield.
Reactivity of neutral nitrogen donors in square-planar d8 metal complexes: The system chloro(2,2′:6′,2″-terpyridine)platinum(II) cation with five-membered N-donor heterocycles in methanol
Pitteri, Bruno,Bortoluzzi, Marco
, p. 2698 - 2704 (2008/10/09)
The kinetics of the forward and reverse steps of the reaction [Pt(terpy)Cl]+ + nu ? [Pt(terpy)(nu)]2+ + Cl- (terpy = 2,2′:6′,2″-terpyridine, nu = one of a number of thiazoles, oxazole, isoxazole, imidazole, pyrazole and 3,5-dimethylpyrazole, covering a wide range of basicities) have been studied in methanol at 25 °C. Both forward and reverse reactions obey the usual two-term rate law observed in square-planar substitution. The second-order rate constants for the forward reactions, k2f, show a slight dependence upon the basicity of the entering nu, while the steric hindrance due to the presence of one methyl group in the α position to the nitrogen markedly decreases the reactivity. The second-order rate constants for the reverse reactions, k2r, are very sensitive to the nature of the leaving group and a plot of log k2r against the pKa of the conjugate acids of the unhindered five-membered N-donors is linear with a slope of -0.51. The results are compared with data from the literature regarding a series of pyridines reacting with the [Pt(terpy)Cl]+ cation under the same experimental conditions. Both in the forward and in the reverse reaction, the reactivity depends not only upon the ligand basicity but also upon the nature of the nucleophile in the order: (thiazoles, oxazole, isoxazole, imidazole, pyrazoles) > pyridines for the entry of N-donors and on the contrary for the displacement by Cl-. Steric retardation, due to the presence of a methyl group in the α position to the nitrogen, is remarkably lower for five-membered N-donors if compared to pyridines both in the forward and in the reverse reaction.
Gastrin and cholecystokinin receptor ligands(II)
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, (2008/06/13)
Substituted imidazoles (1) are useful as angiotensin II blockers. These compounds have activity in treating hypertension and congestive heart failure. Pharmaceutical compositions containing the novel imidazoles and pharmaceutical methods using them, alone and in conjunction with other drugs, especially diuretics and non-steroidal antiinflammatory drugs (NSAID's) are also described.
