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1.
Chemistry ; 25(11): 2786-2792, 2019 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-30520173

RESUMEN

Radical carbofluorination reactions starting from arylhydrazines and nonactivated alkenes, in which the C-F bond is formed through the use of Selectfluor, can be improved through the addition of anisole. Because direct trapping products could be detected only in trace amounts, anisole does primarily act as a reversible scavenger for the highly reactive ammonium radical dication released from Selectfluor in the C-F bond-forming step. As shown for three diverse substitution patterns, the main role of anisole is to prevent, or at least reduce, the undesired addition of the ammonium radical dication to the alkene, which in turn leads to an unfavorable consumption of the arylhydrazine-derived precursors required for carbofluorination. Moreover, besides the remarkable polar effects in radical trapping, this study shows that the Selectfluor-derived nitrogen-centered radical dication may add directly to alkenes, which has not been described so far.

2.
Angew Chem Int Ed Engl ; 58(11): 3599-3603, 2019 Mar 11.
Artículo en Inglés | MEDLINE | ID: mdl-30570208

RESUMEN

The development of versatile functionalization concepts for graphene is currently in the focus of research. Upon oxo-functionalization of graphite, the full surface of graphene becomes accessible for C-C bond formation to introduce out-of-plane functionality. Herein, we present the arylation of graphene with arylazocarboxylic tert-butyl esters, which generates aryl radicals after activation with an acid. Surprisingly, the degree of functionalization is related to the concentration of lattice vacancy defects in the graphene material. Consequently, graphene materials that are free from lattice defects are not reactive. The reaction can be applied to graphene dispersed in solvents and leads to bitopic functionalization as well as monotopic functionalization when the graphene is deposited on surfaces. As the arylazocarboxylic tert-butyl ester moiety can be attached to various molecules, the presented method paves the way to functional graphene derivatives, with the density of defects determining the degree of functionalization.

3.
J Med Chem ; 62(21): 9658-9679, 2019 11 14.
Artículo en Inglés | MEDLINE | ID: mdl-31613617

RESUMEN

Many subtype-selective dopamine receptor ligands developed for the D2-D4 family incorporate a 1-arylpiperazine-derived primary recognition motif, which is connected to a lipophilic moiety occupying an extended binding pocket (EBP) of the receptor via an aliphatic linker of variable lengths. The evaluation of a novel group of dopamine receptor ligands now showed that highly subtype-selective ligands [up to Ki(D4.4) = 0.25 nM, D2L/D4.4 = 320, D3/D4.4 = 710 for APH199 (17)] can be obtained by choosing a relatively large and conformationally flexible 1-benzyl-1-phenylsemicarbazide substructure to fill the EBP. The novel chemotype APH199 (17) was found to act as a full agonist at the D4 receptor showing significant bias toward G protein activation over ß-arrestin recruitment in comparison to quinpirole.


Asunto(s)
Agonistas de Dopamina/química , Agonistas de Dopamina/farmacología , Diseño de Fármacos , Proteínas de Unión al GTP/metabolismo , Receptores de Dopamina D4/metabolismo , Tiosemicarbazonas/química , Tiosemicarbazonas/farmacología , Humanos , Modelos Moleculares , Conformación Proteica , Receptores de Dopamina D4/química , Especificidad por Sustrato
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