31938-10-0Relevant academic research and scientific papers
Studies towards dynamic kinetic resolution of 4-hydroxy-2-methylcyclopent-2-en-1-one and its E-O-trityloxime
Michalak, Karol,Wicha, Jerzy,Wójcik, Jacek
, p. 4813 - 4820 (2016)
Dynamic kinetic resolution through metal complex induced racemization and Candida antarctica lipase mediated enantioselective acetylation of a model hydroxy-ketone: 4-hydroxy-2-methylcyclopent-2-en-1-one and its selected derivatives, has been studied. Racemization of the hydroxy-ketone was efficiently affected by [RuCl2(cymene)]2complex–triethylamine while Shvo's catalyst triggered an intramolecular redox process. Kinetic resolution of 4-hydroxy-2-methylcyclopent-2-en-1-one with C. antarctica under conditions compatible with [RuCl2(cymene)]2racemization failed to reach the efficiency threshold. However, dynamic kinetic resolution of its O-trityloxime using [RuCl2(cymene)]2–triethylamine and C. antarctica lipase–isopropenyl acetate combination, was successfully achieved.
Controlled Supramolecular Assembly Inside Living Cells by Sequential Multistaged Chemical Reactions
Pieszka, Michaela,Han, Shen,Volkmann, Christiane,Graf, Robert,Lieberwirth, Ingo,Landfester, Katharina,Ng, David Y. W.,Weil, Tanja
, p. 15780 - 15789 (2020)
Synthetic assembly within living cells represents an innovative way to explore purely chemical tools that can direct and control cellular behavior. We use a simple and modular platform that is broadly accessible and yet incorporates highly intricate molecular recognition, immolative, and rearrangement chemistry. Short bimodular peptide sequences undergo a programmed sequence of events that can be tailored within the living intracellular environment. Each sequential stage of the pathways beginning with the cellular uptake, intracellular transport, and localization imposes distinct structural changes that result in the assembly of fibrillar architectures inside cells. The observation of apoptosis, which is characterized by the binding of Annexin V, demonstrates that programmed cell death can be promoted by the peptide assembly. Higher complexity of the assemblies was also achieved by coassembly of two different sequences, resulting in intrinsically fluorescent architectures. As such, we demonstrate that the in situ construction of architectures within cells will broaden the community's perspective toward how structure formation can impact a living system.
Constructing hybrid protein zymogens through protective dendritic assembly
Ng, David Y. W.,Arzt, Matthias,Wu, Yuzhou,Kuan, Seah Ling,Lamla, Markus,Weil, Tanja
supporting information, p. 324 - 328 (2014/01/17)
The modulation of protein uptake and activity in response to physiological changes forms an integral part of smart protein therapeutics. We describe herein the self-assembly of a pH-responsive dendrimer shell onto the surface of active enzymes (trypsin, papain, DNase I) as a supramolecular protecting group to form a hybrid dendrimer-enzyme complex. The attachment is based on the interaction between boronic acid and salicyl hydroxamate, thus allowing the macromolecular assembly to respond to changes in pH between 5.0 and 7.4 in a highly reversible fashion. Catalytic activity is efficiently blocked in the presence of the dendrimer shell but is quantitatively restored upon shell degradation under acidic conditions. Unlike the native proteases, the hybrid constructs are shown to be efficiently taken up by A549 cells and colocalized in the acidic compartments. The programmed intracellular release of the proteases induced cytotoxicity, thereby uncovering a new avenue for precision biotherapeutics. The programmed self-assembly of a dendritic shell onto enzymes was used to modulate enzyme activity as well as induce cellular entry and release of the active proteins. The defined dendritic construct represents a contemporary avenue for smart protein therapeutics. Copyright
2-[(arylmethoxy)imino]imidazolidines with potential biological activities
Saczewski, Jaroslaw,Hudson, Alan L.,Rybczynska, Apolonia
experimental part, p. 671 - 680 (2010/07/04)
A series of 2-[(arylmethoxy)imino]imidazolidines was synthesized by reacting 2-chloro-4,5-dihydroimidazole with corresponding O- arylmethylhydroxylamines and evaluated for their α1-, α2-adrenergic and imidazoline I1, I2 receptor binding affinities. The most potent 2-[(naphthalen-1-ylmethoxy)imino] imidazolidine showed a high selectivity and good affinity for the [ 3H]prazosin-labeled α1-adrenoceptors (Ki = 107 nM). Representative compounds of this series were also tested in vivo for possible circulatory effects in rats after intravenous administration.
Approach to 3-aminoindolin-2-ones via oxime ether functionalized carbamoylcyclohexadienes
Bella, A. Franco,Slawin, Alexandra M. Z.,Walton, John C.
, p. 5926 - 5933 (2007/10/03)
O-Benzyloxime ether substituted amidocyclohexadienes were prepared in three steps in good yields from 2-aminoacetophenone. EPR spectroscopic observations and product analyses showed that peroxide-induced decompositions of model compounds led to indolin-2-ones with benzyloxyaminyl substitution at their 3-positions. The cyclization steps were very rapid and took place regioselectively at the C-atoms of the C=N bonds, by 5-exo ring closures. An O-trityloxime ether analogue was also prepared. The cyclohexadienyl intermediate smoothly yielded an alkoxylaminyl radical again by rapid 5-exo-cyclization. However, ring closure was quickly followed by another β-scission step that released the persistent trityl radical and a 3-nitrosoindolin-2-one derivative. EPR spectroscopic evidence showed that the nitroso compound trapped other transient intermediates to afford a series of nitroxides. GC-MS analyses of products formed in reactions including methyl thioglycolate indicated that 1-benzyl-3-methyl-1,3-dihydro-2H-indol-2-one was derived from the indolinone moiety.
Factors Affecting the Stability and Equilibria of Free Radicals. XIII. N-Alkoxy- and N-Aralkoxypicrylamines and ESR Spectra of the Corresponding Capto-Dative Persistent Aminyls
Stanciuc, Gabriela,Caproiu, M. Teodor,Caragheorgheopol, Agneta,Caldararu, Horia,Balaban, Alexandru T.,Walter, Robert I.
, p. 63 - 72 (2007/10/02)
Five O-alkylhydroxylamines and three aralkylhydroxylamines have been picrylated to give O-alkyl-N-picrylhydroxylamines.These were converted to the corresponding N-(ar)alkoxy-picryl-aminyl radicals in toluene solution, and the ESR spectra were recorded.Simulations of the spectra with reasonable parameters and g values confirm the expected radical structures.Hyperfine coupling constants for nuclei in the picryl (acceptor) ring are smaller than those for the (ar)alkoxy group.This indication of competitive electron pair delocalization to the picryl ring, together with the long lifetimes of these radicals (compared with the symmetrically substituted diphenylaminyls), both support the concept of captodative stabilization.
