Cyclic Urea Research Articles

ChemInform Abstract: A Pyrone, Naphthoquinone, and Cyclic Urea from the Marine‐Derived Fungus Astrosphaeriella nypae BCC 5335

Abstractisolation and structure elucidation of astronypyrone (I), astronyquinone (II), and astronyurea (III)

Nondestructive Molecular Characterization of Polycarbonate–Polyvinylamine Composites after Thermally Induced Aminolysis

Thermal induced solid phase polymer reactions between bisphenol‐A‐based polycarbonate (PC) and polyvinylamine (PVAm) are used to form permanent composite material. The PC–PVAm interface is characterized by infrared (IR) spectroscopy. IR spectra of synthesized reference substances which can be expected after PC–PVAm reaction are recorded and used to identify amidation product structures within the PC–PVAm interphase. Curve fit analysis is performed to isolated sub‐bands. The spectral position of the carbonyl absorption band is a suitable marker for the identification of different amidation products. While the formation of urethane and cyclic Allophanate points to the formation of a co‐polymer cyclic Urea indicates a PC chain scission without binding between both polymer materials. image

Synthesis of some tetrahydropyrimidine-5-carboxylates, determination of their metal chelating effects and inhibition profiles against acetylcholinesterase, butyrylcholinesterase and carbonic anhydrase

2-(Methacryloyloxy)ethyl 6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxylate, is a cyclic urea derivative synthesized from urea, 2-(methacryloyloxy) ethyl acetoacetate and substituted benzaldehyde, and tested in terms of the inhibition of two physiologically relevant carbonic anhydrase (CA) isozymes I and II. Acetylcholinesterase (AChE) is found in high concentrations in the red blood cells and brain. Butyrylcholinesterase (BChE) is another enzyme abundantly present in the liver and released into blood in a soluble form. Also, they were tested for the inhibition of AChE and BChE enzymes and demonstrated effective inhibition profiles with Ki values in the range of 429.24–530.80 nM against hCA I, 391.86–530.80 nM against hCA II, 68.48–97.19 nM against AChE and 104.70–214.15 nM against BChE. On the other hand, acetazolamide clinically used as CA inhibitor, showed Ki value of 281.33 nM against hCA I, and 202.70 nM against hCA II. Also, Tacrine inhibited AChE and BChE showed Ki values of 396.03 and 209.21 nM, respectively.

Hofmann Rearrangement of Carboxamides Mediated by N-Bromo­acetamide

An efficient, one-pot procedure for the Hofmann rearrangement of aromatic and aliphatic amides has been developed. Methyl and benzyl carbamates are produced with N-bromoacetamide in the presence of lithium hydroxide or lithium methoxide, in high yields. β-Phenylamino amides gave five-membered cyclic ureas stereospecifically. Side products of aryl or benzyl bromination were minimized. This procedure offers an easy access to various protected amines or diamines, which represent important synthetic precursors.

A pyrone, naphthoquinone, and cyclic urea from the marine-derived fungus Astrosphaeriella nypae BCC 5335

The novel compounds, astronypyrone, astronyquinone, and astronyurea, together with three known compounds, xestodecalactone A, ent-coryoctalactone B, and dimethoxy-O-methylpulvinone were isolated from the marine-derived fungus Astrosphaeriella nypae BCC 5335. Their structures were elucidated on the basis of NMR spectroscopy and mass spectrometry data. Astronypyrone possesses a 2-pyrone derivative fused with a tetrahydrofuran moiety via a dihydropyran unit, while the 2-pyrone ring is substituted by a naphthoquinone skeleton in astronyquinone.

Chemo-sorption nonwoven textile materials for purification of waste waters containing Cu**

Proposed is a method and product for UV radiation modification of the surface of the needle-felted non-woven metrerial from polyethylene terephthalate standard fibers, for obtaining of ion exchange filters. The fibers obtained should possess a 3D structure and a high hydrolytic stability, which has to guarantee their multiple usage during the numerous sorption processes. As surface modifiers are used Polyethilenimine (PEI), grafted on the surface of the PET fibers with the Epichlorhydrin, Dimethylol dihydroxy cyclic ethylene urea (DMDHEU- C5H10N2O5, Glyoxal (C2H2O2).5. The filter materials obtained are highly effective towards the retention of Cu2+ from industrial waste waters.

A Modular Synthesis of Conformationally Preorganised Extended β-Strand Peptidomimetics.

A promising strategy for mediating protein-protein interactions is the use of non-peptidic mimics of secondary structural protein elements, such as the α-helix. Recent work has expanded the scope of this approach by providing proof-of-principle scaffolds that are conformationally biased to mimic the projection of side-chains from one face of another common secondary structural element-the β-strand. Herein, we present a synthetic route that has key advantages over previous work: monomers bearing an amino acid side-chain were pre-formed before rapid assembly to peptidomimetics through a modular, iterative strategy. The resultant oligomers of alternating pyridyl and six-membered cyclic ureas accurately reproduce a recognition domain of several amino acid residues of a β-strand, demonstrated herein by mimicry of the i, i+2, i+4 and i+6 residues.

Catalyst-Controlled Amino- versus Oxy-Acetoxylation of Urea-Tethered Alkenes: Efficient Synthesis of Cyclic Ureas and Isoureas.

A catalyst-controlled vicinal amino- versus oxy-acetoxylation of alkenes with PhI(OAc)2 as the oxidant is described. The divergent synthesis of cyclic ureas and isoureas was achieved in good yields under mild conditions employing ambident urea nucleophiles. Both terminal and internal alkenes are compatible with this reaction protocol.

Correlation between intermolecular hydrogen bonds and melting points of uranyl nitrate complexes with cyclic urea derivatives

To clarify requirements for forming UO2(NO3)2(CU)2 (CU: cyclic urea derivative) and UO2(NO3)2(NRP)2 (NRP: N-alkylated pyrrolidone derivative) with high melting points (mps), molecular and crystal structures of UO2(NO3)2(0a)2 (0a: 2-imidazolidone), UO2(NO3)2(0b)2 (0b: tetrahydro-2-pyrimidone) and UO2(NO3)2(1a)2 (1a: 1-methyl-2-imidazolidone) were determined by means of single crystal X-ray analysis. Melting points (mps) of these complexes were compared with each other and those of other UO2(NO3)2(CU)2 and UO2(NO3)2(NRP)2. As a result, the uranyl nitrate complexes with 0a, 0b and 1a exhibit typical structural properties of UO2(NO3)2L2 (L: unidentate ligand); i.e., hexagonal bipyramidal coordination geometry, and two bidentate NO3− and two CUs located at trans positions in an equatorial plane of UO22+ ion. Several intermolecular N–H⋯O hydrogen bonds (HBs) were found in the crystal structures of UO2(NO3)2(0a)2, UO2(NO3)2(0b)2 and UO2(NO3)2(1a)2. In contrast, no intermolecular C–H⋯O HBs were formed in these crystal structures. The intermolecular HBs were discussed in connection with mps of UO2(NO3)2(CU)2 and UO2(NO3)2(NRP)2 including those reported previously. The mp tends to increase as the number of N–H⋯O HBs per molecule increases, whereas effects of C–H⋯O HBs on the mps is not very significant. These results suggest that the intermolecular N–H⋯O HBs strongly contribute to form a uranyl nitrate complex with high mps.

Design and synthesis of biotin analogues reversibly binding with streptavidin.

Two new biotin analogues, biotin carbonate 5 and biotin carbamate 6, have been synthesized. These molecules were designed to reversibly bind with streptavidin by replacing the hydrogen-bond donor NH group(s) of biotin's cyclic urea moiety with oxygen. Biotin carbonate 5 was synthesized from L-arabinose (7), which furnishes the desired stereochemistry at the 3,4-cis-dihydroxy groups, in 11% overall yield (over 10 steps). Synthesis of biotin carbamate 6 was accomplished from L-cysteine-derived chiral aldehyde 33 in 11% overall yield (over 7 steps). Surface plasmon resonance analysis of water-soluble biotin carbonate analogue 46 and biotin carbamate analogue 47 revealed that KD values of these compounds for binding to streptavidin were 6.7×10(-6) M and 1.7×10(-10) M, respectively. These values were remarkably greater than that of biotin (KD =10(-15) M), and thus indicate the importance of the nitrogen atoms for the strong binding between biotin and streptavidin.

Synthesis of ferrocene-containing six-membered cyclic ureas via α-ferrocenyl carbocations

A convenient method for the synthesis of ferrocene-containing six membered cyclic ureas was developed.

Pyridoxine-derived bicyclic amido-, ureido-, and carbamato-pyridinols: synthesis and antiangiogenic activities

We recently developed an efficient and practical synthesis for a novel series of pyridoxine-derived 6-amido-2,4,5-trimethylpyridin-3-ols and found that this novel scaffold has outstanding activity to inhibit angiogenesis measured by the quantitative chick embryo chorioallantoic membrane (CAM) assay. As an effort to extend the scope of the amidopyridinol scaffold, we here report the synthesis and antiangiogenic activities of a series of bicyclic versions of the amidopyridinol including five- and six-membered cyclic amide-, cyclic urea-, and cyclic carbamate-fused pyridinols. The six membered bicyclic derivatives were prepared by the reported procedures, and the five-membered ring-fused ones were synthesized by new synthetic methods developed in this study. CAM assays showed that both six- and five-membered lactam-fused pyridinols have activities comparable to sunitinib malate, the positive control, in inhibition of vascular endothelial growth factor-induced angiogenesis. On the other hand, the urea and the carbamate derivatives showed modest to moderate antiangiogenic activities. In summary, some bicyclic aminopyridinols can provide a good platform for structural exploitation in future medicinal chemistry work.

ChemInform Abstract: Direct Conversion of CO2 with Diols, Amino Alcohols and Diamines to Cyclic Carbonates, Cyclic Carbamates and Cyclic Ureas Using Heterogeneous Catalysts.

ChemInform Abstract: Direct Conversion of CO₂ with Diols, Amino Alcohols and Diamines to Cyclic Carbonates, Cyclic Carbamates and Cyclic Ureas Using Heterogeneous Catalysts.

Cytotoxicity and 2D-QSAR study of some heterocyclic compounds

Herein we have studied the cytotoxicity and quantitative structure–activity relationship (QSAR) of heterocyclic compounds containing cyclic urea and thiourea nuclei. A set of 22 hydantoin and thiohydantoin related heterocyclic compounds were investigated with respect to their LC50 values (Log of LC50) against brine shrimp lethality bioassay in order to derive the 2D-QSAR models using MLR, PLS and ANN methods. The best predictive models by MLR, PLS and ANN methods gave highly significant square correlation coefficient (R2) values of 0.83, 0.81 and 0.91 respectively. The model also exhibited good predictive power confirmed by the high value of cross validated correlation coefficient Q2 (0.74).

A study on selective precipitation of U(VI) by hydrophilic cyclic urea derivatives for development of a reprocessing system based on precipitation method

Selective precipitation ability of 2-imidazolidone (EU) and tetrahydro-2-pyrimidinone (PU) for U(VI) species in HNO3 solutions containing U(VI), U(IV) (simulant of Pu(IV)), and simulated fission products (FPs) was investigated. As a result, it was found that these compounds precipitate almost quantitatively U(VI) as UO2(NO3)2L2 (L = EU, PU) from 3.0 M HNO3 solution. In contrast, these urea derivatives form neither solid precipitates nor oily products with U(IV) in HNO3 solutions containing only U(IV) species and even in U(VI)–U(IV) admixture system. Therefore, the separation of U(VI) from U(IV) was demonstrated to be achieved in use of EU and PU. Furthermore, EU and PU are capable to remove most of simulated FPs[Sr(II), Ru(III), Rh(III), Re(VII) La(III), Ce(III), Pr(III), Nd(III), and Sm(III)] from U(VI) to give their decontamination factors (DFs) higher than 100, while those values of Zr(IV), Mo(VI), Pd(II), and Ba(II) are necessary to be improved in both systems. From these results, it is expected that EU and PU are the promising precipitants for selective separation of U(VI) from HNO3 solutions dissolving spent FBR fuels.

ChemInform Abstract: Synthetic Approaches to Tetracyclic Pyrrole Imidazole Marine Alkaloids

AbstractReview: 15 refs.

Scope of chemical fixation of carbon dioxide catalyzed by a bifunctional monomeric tungstate

The tungsten-oxo moiety in a simple monomeric tungstate, TBA2[WO4] (I, TBA=tetra-n-butylammonium), showed bifunctional activation of both CO2 and 1,2-phenylenediamine (1a). It was confirmed by 1H, 13C, and 183W NMR spectroscopies that adducts I–1a and I–(CO2)n (n=1 and 2) were formed by the reactions of I with 1a and CO2, respectively. These adducts played important roles in formation of the corresponding carbamic acid intermediates. The present bifunctionality could be applied to chemical fixation of CO2 even at atmospheric pressure with various kinds of structurally diverse aryl diamines, primary monoamines, propargylic alcohols, and propargylic amines into cyclic urea derivatives, 1,3-disubstituted urea derivatives, cyclic carbonates, and cyclic carbamates, respectively.

Direct conversion of CO2 with diols, aminoalcohols and diamines to cyclic carbonates, cyclic carbamates and cyclic ureas using heterogeneous catalysts

AbstractCO2 has a large effect on global warming by greenhouse gases, and development of an effective technique for the reduction of CO2 is a crucial and urgent issue. From the chemical viewpoint, CO2 is regarded as a stable, safe and abundant C1 resource, and the transformation of CO2 to valuable chemicals is promising not only for reduction of CO2 but also for production of useful chemicals. This mini‐review focuses on the direct conversion of CO2 with diols, aminoalcohols and diamines to cyclic compounds such as cyclic carbonates, cyclic carbamates and cyclic ureas, and in particular discusses the mechanisms for these reactions over heterogeneous catalysts. © 2013 Society of Chemical Industry

ChemInform Abstract: Highly Efficient Synthesis of Cyclic Ureas from CO2 and Diamines by a Pure CeO2 Catalyst Using a 2‐Propanol Solvent.

Pure cerium oxide (CeO2) acts as an effective and reusable heterogeneous catalyst for direct synthesis of cyclic ureas from CO2 and diamines even at a low CO2 pressure of 0.3 MPa. 2-Propanol is the most preferable solvent to provide good selectivity. The system composed of a CeO2 catalyst and a 2-propanol solvent is applied to various diamines to provide the corresponding cyclic ureas in high yields (78–98%), including six-membered-ring ureas that are difficult to be synthesized from CO2. Based on the kinetic studies on the effect of CO2 pressure and amine concentration and FTIR studies on adsorption of ethylenediamine and CO2 onto CeO2, the following mechanism for the synthesis of cyclic urea is proposed: (1) formation of carbamic acid and carbamate species on CeO2, (2) decomposition of carbamic acid to a free amino group and CO2, (3) nucleophilic attack of the amino group on the carbamate on CeO2 to produce the cyclic urea and (4) desorption of the product and regeneration of CeO2.

Ultrasound-promoted efficient domino reaction for the one-pot synthesis of spiro-5-cyanopyrimidines: a rapid procedure

A novel and efficient protocol has been developed for the synthesis of various spiro-5-cyanopyrimidines via the three-component condensation of cyclic ketones, nitrile derivatives, and thiourea or urea in ethanol at 60 °C using K2CO3 as catalyst under ultrasonic irradiation. In comparison to conventional methods, high yields, easy work-up, and short reaction times are advantages of this sonocatalyzed procedure. The effects of the catalyst, solvent, and temperature were examined. .