RESUMO
The comparison of the possibilities of Pd- and Cu-catalyzed amination reactions using fluorine-containing aryl bromides and iodides with oxadiamines to produce their N,N'-diaryl derivatives was carried out. The dependence of the reactivity of the aryl halides on the nature of the substituents and halogen atoms as well as on the structure of oxadiamines was investigated. It was found that the copper-catalyzed reactions were somewhat comparable with the palladium-mediated processes in the majority of cases, especially in the reactions with para-fluorine- and para-(trifluoromethyl)-substituted aryl halides, although the necessity to use aryl iodides in the Cu(I)-catalyzed amination was obvious. Pd catalysis was found inevitable for the successful amination of more sterically hindered ortho-(trifluoromethyl)aryl bromides.
Assuntos
Aminas/química , Cobre/química , Hidrocarbonetos Fluorados/química , Paládio/química , CatáliseRESUMO
The arylation of mono-, di- and tetra-meso-bromophenyl-substituted porphyrins with the heteroarenes containing "acidic" C-H bonds, such as benzoxazole, benzothiazole and N-methylimidazole was studied in the presence of three alternative catalytic systems: Pd(dba)2/DavePhos/Cs2CO3, Pd(PPh3)4/PivOH/K2CO3 and Pd(OAc)2/Cu(OAc)2/PPh3/K2CO3. The first catalytic system was found to be successful in the reaction with benzoxazole, the second one was less efficient for our purpose, while the third system proved to be most versatile and afforded corresponding mono-, di-, tri- and even tetraarylated derivatives of porphyrins.
RESUMO
BACKGROUND: This article reports a rare case of active neurosyphilis in a man with mild to moderate dementia and marked hippocampal atrophy, mimicking early onset Alzheimer's disease. Few cases have so far described bilateral hippocampal atrophy mimicking Alzheimer's disease in neurosyphilis. CASE PRESENTATION: The patient presented here is a 33 year old Bulgarian male, whose clinical features include progressive cognitive decline and behavioral changes over the last 18 months. Neuropsychological examination revealed mild to moderate dementia (Mini Mental State Examination score was 16/30) with impaired memory and attention, and executive dysfunction. Pyramidal, and extrapyramidal signs, as well as dysarthria and impairment in coordination, were documented. Brain magnetic resonance imaging showed cortical atrophy with noticeable bilateral hippocampal atrophy. The diagnosis of active neurosyphilis was based on positive results of the Venereal Disease Research Laboratory test/Treponema pallidum hemagglutination reactions in blood and cerebrospinal fluid samples. In addition, cerebrospinal fluid analysis showed pleocytosis and elevated protein levels. High-dose intravenous penicillin therapy was administered. At 6 month follow up, improvements were noted clinically, on neuropsychological examinations, and in cerebrospinal fluid samples. CONCLUSION: This case underlines the importance of early diagnosis of neurosyphilis. The results suggest that neurosyphilis should be considered when magnetic resonance imaging results indicate mesiotemporal abnormalities and hippocampal atrophy. Neurosyphilis is a treatable condition which requires early aggressive antibiotic therapy.