(Thio)urea Organocatalysts

Kotke, Mike; Schreiner, Peter R.

doi:10.1002/9783527627844.ch6

Cited by 88 publications

(56 citation statements)

References 316 publications

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“…The lower recognition of the structurally similar thio-CPPU can be probably attributed to the different hydrogen bond pattern showed by the ureido and thioureido moieties due to the higher acidity of the thioureidic hydrogens 5 and, particularly, the much weaker hydrogen-bond acceptor capability of the thiocarbonyl group. 24 Concerning TDZ recognition, a highly diverse binding was observed; some mAbs, such as p6#23, showed low AR values, whereas other antibodies such as s5#12 presented recognition over 100%. The medium-to- Based on the results herein presented, it could be hypothesized that the interaction between the generated antibodies and CPPU 20 could be in first instance mainly driven by electrostatic forces, being in this sense the polarization associated to the 2-chloropyridyl ring highly determinant.…”

Section: Figure 2 Analysis Of the Binding Properties Of The Antibodiementioning

confidence: 98%

Forchlorfenuron-mimicking haptens: from immunogen design to antibody characterization by hierarchical clustering analysis

et al. 2011

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To obtain high-specific and selective forchlorfenuron binders, a collection of functionalized derivatives with different spacer arm locations and lengths was prepared. By immunization with target-mimicking haptens, a large battery of monoclonal and polyclonal antibodies against this synthetic cell regulator was produced and exhaustively characterized in two immunoassay formats using homologous and 10 heterologous conjugates. Antibodies with IC 50 values lower than 0.3 nM were successfully raised from the prepared immunogens, thus evidencing the efficacy of the explored strategies. In order to identify significant epitopes in the antibody-antigen interaction, a series of new chemical forchlorfenuron analogues, with slight modifications at both rings of the target molecule, were synthesized and evaluated in competitive assays. As a novel approach in hapten recognition studies, data processing was performed 15 by computational classification methods based on hierarchical clustering. This strategy was shown to be highly valuable for a straightforward profiling of antibodies according to analogue recognition patterns. A relationship could be established between the antigen binding properties of antibodies and the structure of the immunogen. Whereas antibodies with equivalent affinities had been obtained from all of the derivatives, their specificity was found to be largely influenced by the differential exposition of the 20 molecule to the immune system. IntroductionSmall organic molecules need to be covalently coupled to immunogenic carriers in order to obtain antibodies. Therefore, derivatives incorporating a functional chemical group and a 25 spacer arm ought to be synthesized for most substances. A successful production of antibodies mostly relies on the structure of the prepared immunogen, 1 and hence the immunizing hapten should resemble the target compound almost perfectly. It is well established that a certain immunizing derivative should preserve 30 as much as possible the physicochemical characteristics of the target molecule (steric, electronic, and geometric properties), and therefore the position, composition, and length of the spacer arm are critical aspects in hapten design.2 Particularly, the derivatization site within the immunizing hapten, and thus the 35 differential presentation of the immunogen to the immune system, is known to have a strong effect on antibody properties, especially on their specificity.3 During the last years, computerassisted molecular modelling techniques have been introduced and structure-activity relationship studies have been carried out 40 to provide useful information with regard to immunogen design. 4 However, prediction of the structure of the perfect immunizing hapten still remains a challenge. Consequently, for the generation of high-affinity and selective antibodies, it is strongly recommended to prepare an assortment of compounds mimicking 45 the analyte of interest and containing a functional linker at different positions, thus facilitating the presentatio...

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Section: Figure 2 Analysis Of the Binding Properties Of The Antibodiementioning

confidence: 98%

Forchlorfenuron-mimicking haptens: from immunogen design to antibody characterization by hierarchical clustering analysis

et al. 2011

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“…Compounds of this class have not been previously structurally characterized, despite the fact that N , N ′-disubstituted thioureas have varied applications. 20,21 Some examples of these applications include their use (i) as antibacterial, 22,23,24 antifungal, 24,25 antiviral, 26,27,28 anti-HIV, 28 antimalarial, 23 antituberculous, 28,29 antihistamine, 30 and anticancer 27 agents, (ii) in organocatalysis, 31,32,33 and (iii) in crystal engineering. 34,35 …”

Section: Introductionmentioning

confidence: 99%

Synthesis and structural characterization of 1-arylimidazole-2-thiones and N,N′-aryldiethoxyethylthioureas with electronically diverse substituents: a manifold of hydrogen bonding networks

Palmer

Parkin

2014

New J. Chem.

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The 1-arylimidazole-2-thiones, (HmimAr) [Ar = 3,4,5-C6H2(OMe)3, 2,4-C6H3(NO2)(OMe), 2,4,6-C6H2Cl3 and 3,5-C6H3(CF3)2], which feature electronically diverse substituents, may be obtained via acid-catalyzed ring closure of the corresponding N,N′-aryldiethoxyethylthiourea derivatives, ArN(H)C(S)N(H)CH2CH(OEt)2, (H2detuAr), which in turn are obtained via treatment of aminoacetaldehyde diethyl acetal, H2NCH2CH(OEt)2, with the respective arylisothiocyanates (ArNCS). The molecular structures of all of the above N,N′-aryldiethoxyethylthioureas and 1-arylimidazole-2-thiones have been determined by X-ray diffraction, thereby demonstrating that the substituents have a profound effect on the crystal structures. For example, each of the N,N′-aryldiethoxyethylthiourea derivatives adopts a different hydrogen bonding pattern. Specifically, the hydrogen-bonding network in (i) H2detuArCl3 consists of chains of 9-membered rings, with an [ R22(9)] motif, that feature one N–H ⋯ O and one N–H ⋯ S interaction, (ii) H2detuArOMe,NO2 consists of chains of 6-membered rings, with an [ R21(6)] motif, that feature two head-to-tail N–H ⋯ S interactions, (iii) H2detuAr(CF3)2 consists of a dimer that features two pairs of N–H ⋯ O interactions, of which each pair is a component of an 8-membered ring with an [ R22(8)] motif, and (iv) H2detuAr(OMe)3 consists of a chain of head-to-head dimeric rings with a basic [ R22(16)] motif, a notable feature of which is that sulfur does not play a role as a hydrogen bond acceptor. Each of the 1-arylimidazole-2-thiones exists as a “head-to-head” hydrogen-bonded dimer in the solid state, with an [ R22(8)] motif. However, while the hydrogen-bonded motifs for HmimArCl3 and HmimAr(OMe)3 are planar, those for HmimAr(CF3)2 and HmimArOMe,NO2 are extremely puckered, with fold angles of 24.2° (mean value) and 45.7°, respectively.

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“…Hydrogen bonding interactions play a key role in noncovalent organocatalysis, [33][34][35] thus determination of pK a values facilitate the understanding of catalytic activity and catalyst design. However, the equilibrium values have their limitations for a kinetic property such as transition state stabilization.…”

Section: Pk a Measurementsmentioning

confidence: 99%

Synthesis and determination of pKa values of new enantiopure pyridino- and piperidino-18-crown-6 ethers

Kupai

Kisszékelyi

Rojik

et al. 2016

Arkivoc

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This paper reports the preparation of eight new enantiopure amide type crown ethers and their optically active precursors. Chiral diamines were transformed to amide type pyridino-crown ethers reacting them with pyridine dicarbonyl dichlorides by high dilution technique. Two of the new pyridino-crown ethers were reduced to their piperidino analogues. A preliminary study for the potential application of nanofiltration in the purification and recovery of crown ethers is presented. According to the pK a measurements these eight new macrocycles are potential organocatalysts (for instance in Michael addition reactions) thanks to their acidic and basic moieties and chiral skeletons, respectively.

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(Thio)urea Organocatalysts

Cited by 88 publications

References 316 publications

Forchlorfenuron-mimicking haptens: from immunogen design to antibody characterization by hierarchical clustering analysis

Forchlorfenuron-mimicking haptens: from immunogen design to antibody characterization by hierarchical clustering analysis

Synthesis and structural characterization of 1-arylimidazole-2-thiones and N,N′-aryldiethoxyethylthioureas with electronically diverse substituents: a manifold of hydrogen bonding networks

Synthesis and determination of pKa values of new enantiopure pyridino- and piperidino-18-crown-6 ethers

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