Synthesis,Characterization, and Anti‐Amoebic Activity of N‐(Pyrimidin‐2‐yl)benzenesulfonamide Derivatives

A new series of N‐(pyrimidin‐2‐yl)benzenesulfonamide derivatives, 3a – 3i and 4a – 4i , was synthesized from pyrimidin‐2‐amines, 2a – 2i , with the aim to explore their effects on in vitro growth of Entamoeba histolytica. The chemical structures of the compounds were elucidated by elemental analysis, FT‐IR, ¹H‐ and ¹³C‐NMR, and ESI mass‐spectral data. In vitro anti‐amoebic activity was evaluated against HM1 : IMSS strain of Entamoeba histolytica. The IC₅₀ values were calculated by using the double dilution method. The results were compared with the IC₅₀ value of the standard drug ‘metronidazole’. The selected compounds were tested for their cytotoxic activities by cell‐viability assay using H9C2 cardiac myoblasts cell line, and the results indicated that all the compounds displayed remarkable >80% viabilities to a concentration of 100 μg/ml.     

Synthesis of a New Series of 1H‐Imidazol‐1‐yl Substituted 8‐Phenylxanthines as Adenosine Receptor Ligands

A new series of 1H‐imidazol‐1‐yl substituted 8‐phenylxanthine analogs has been synthesized to study the effects of the imidazole group on the binding affinity of compounds for adenosine receptors. Competition binding studies of these compounds were carried out in vitro with human cloned receptors using [³H]DPCPX and [³H]ZM 241385 as radioligands at A₁ and A_2A adenosine receptors, respectively. The effect of the substitution pattern of the (imidazolyl)alkoxy group on various positions of the phenyl ring at C(8) was also studied. The xanthine derivatives displayed varying degrees of affinity and selectivity towards A₁ and A_2A receptor subtypes despite a common but variedly substituted Ar C(8).     

Mitsunobu Alkylation of Cancerostatic 5‐Fluorouridine with (2E)‐10‐Hydroxydec‐2‐enoic Acid,a Fatty Acid from Royal Jelly with Multiple Biological Activities

5‐Fluorouridine ( 1 ) – a nucleoside antimetabolite with strong cancerostatic properties – was protected i) at the 2′‐ and 3′‐OH groups with a heptan‐4‐ylidene residue and ii) at the 5′‐OH group with a (4‐methoxyphenyl)(diphenyl)methyl residue. This fully protected compound, 3 , was submitted to a Mitsunobu reaction with the N‐hydroxysuccinimide (NHS) ester, 5 , of (2E)‐10‐hydroxydec‐2‐enoic acid ( 4 ) which gave nucleolipid 6 . The latter was detritylated with Cl₂CHCOOH to yield the co‐drug 7 as NHS ester.     

Identification of a naturally‐occurring 8‐[α‐D‐glucopyranosyl‐(1→6)‐β‐D‐glucopyranosyl]daidzein from cultivated kudzu root

Introduction – Kudzu root (Radix puerariae) is a rich source of isoflavones that are effective in preventing osteoporosis, heart disease and symptoms associated with menopause. The major isoflavonoids in kudzu root extracts were reported as puerarin, daidzin and daidzein. Recently, an unknown isoflavonoid (compound 1) was detected from one‐year‐old kudzu root cultivated in Vietnam. Objective – To identify a novel compound 1 in kudzu root extract and determine the structure of the compound by ESI⁺ TOF MS‐MS, ¹H‐, ¹³C‐NMR and enzymatic hydrolysis. Methodology – Samples were prepared by extraction of one‐year‐old kudzu root with 50% ethanol and the isoflavonoids were purified using recycling preparative HPLC. Unknown compound 1 was detected using UV‐light at 254 nm in TLC and HPLC analyses. The molecular weight of 1 was determined using a TOF mass spectrometer equipped with an electrospray ion source. The structure of 1 was determined from the ¹³C and ¹H NMR spectra recorded at 100.40 and 400.0 MHz, respectively. Results – ESI⁺ TOF MS‐MS analysis shows that 1 is a puerarin diglycoside. The interglycosidic linkage of diglycoside determined by ¹H‐, ¹³C‐NMR, and enzymatic hydrolysis suggests that 1 has a glucosyl residue linked to puerarin by an α‐1,6‐glycosidic bond. This compound is the first naturally‐occurring 8‐[α‐D ‐glucopyranosyl‐(1→6)‐β‐D ‐glucopyranosyl]daidzein in kudzu root. The concentration of glucosyl‐α‐1,6‐puerarin in kudzu root was 2.3 mg/g as determined by HPLC. Conclusion – The results indicate that puerarin diglycoside is one of the major isoflavonoids in kudzu root and has a significant impact on the preparation of highly water‐soluble glycosylated puerarin. Copyright © 2009 John Wiley & Sons, Ltd.     

Bioactive 9,11‐Secosteroids from Gorgonian Subergorgia suberosa Collected from the South China Sea

Five new 9,11‐secosteroids 1, 2 , and 4 – 6 , and seven known analogs, 3 and 7 – 12 , with the same steroid skeleton, (5αH)‐3β,6α,11‐trihydroxy‐9,11‐secocholest‐7‐en‐9‐one, were isolated from the South China Sea gorgonian Subergorgia suberosa. Among them, 2 / 3 and 4 / 5 are C(24)‐epimeric mixtures, and 6 / 7 is an (E)/(Z) mixture of (C(24)?C(28)). Their structures and relative configurations were elucidated by using comprehensive spectroscopic methods including NOESY spectra. The absolute configuration of the steroidal nucleus was established by the modified Mosher method applied to 10 and on the basis of a common biogenesis for all of these compounds. All isolated compounds, 1 – 12 , and five synthetic acetylated derivatives, 12a – 12e , were evaluated for their cytotoxicities in vitro. Compounds 4 / 5, 11, 12 , and 12b – 12d showed cytotoxic activities against K562 cell line with the IC₅₀ values ranging from 1.09 to 8.12 μM .     

1,2,3‐Triazole Tagged 3H‐Pyrano[2,3‐d]pyrimidine‐6‐carboxylate Derivatives: Synthesis,in Vitro Cytotoxicity,Molecular Docking and DNA Interaction Studies

A series of novel ethyl 2,7‐dimethyl‐4‐oxo‐3‐[(1‐phenyl‐1H‐1,2,3‐triazol‐4‐yl)methyl]‐4,5‐dihydro‐3H‐pyrano[2,3‐d]pyrimidine‐6‐carboxylate derivatives 7a – 7m were efficiently synthesized employing click chemistry approach and evaluated for in vitro cytotoxic activity against four tumor cell lines: A549 (human lung adenocarcinoma cell line), HepG2 (human hematoma), MCF‐7 (human breast adenocarcinoma), and SKOV3 (human ovarian carcinoma cell line). Among the compounds tested, the compounds 7a , 7b , 7f , 7l , and 7m have shown potential and selective activity against human lung adenocarcinoma cell line (A549) with IC₅₀ ranging from 0.69 to 6.74 μm . Molecular docking studies revealed that the compounds 7a , 7b , 7f , 7l , and 7m are potent inhibitors of human DNA topoisomerase‐II and also showed compliance with stranded parameters of drug likeness. The calculated binding constants, k_b, from UV/VIS absorptional binding studies of 7a and 7l with CT‐DNA were 10.77 × 10⁴, 6.48 × 10⁴, respectively. Viscosity measurements revealed that the binding could be surface binding mainly due to groove binding. DNA cleavage study showed that 7a and 7l have the potential to cleave pBR322 plasmid DNA without any external agents.     

Mitsunobu Reactions of 5‐Fluorouridine with the Terpenols Phytol and Nerol: DNA Building Blocks for a Biomimetic Lipophilization of Nucleic Acids

The cancerostatic 5‐fluorouridine (5‐FUrd; 1 ) was sequentially sugar‐protected by introduction of a 2′,3′‐O‐heptylidene ketal group (→ 2 ), followed by 5′‐O‐monomethoxytritylation (→ 3 ). This fully protected derivative was submitted to Mitsunobu reactions with either phytol ((Z and E)‐isomer) or nerol ((Z)‐isomer) to yield the nucleoterpenes 4a and 4b . Both were 5′‐O‐deprotected with 2% Cl₂CHCOOH in CH₂Cl₂ to yield compounds 5a and 5b , respectively. These were converted to the 5′‐O‐cyanoethyl phosphoramidites 6a and 6b , respectively. Moreover, the 2′,3′‐O‐(1‐nonyldecylidene) derivative, 7a , of 5‐fluorouridine was resynthesized and labelled at C(5′) with an Eterneon‐480 fluorophor^® (→ 7b ). The resulting nucleolipid was studied with respect to its incorporation in an artificial bilayer, as well as to its aggregate formation. Additionally, two oligonucleotides carrying terminal phytol‐alkylated 5‐fluorouridine tags were prepared, one of which was studied concerning its incorporation in an artificial lipid bilayer.     

Antioxidation and DNA‐Binding Properties of Binuclear Lanthanide(III) Complexes with a Schiff Base Ligand Derived from 8‐Hydroxyquinoline‐7‐carboxaldehyde and Benzoylhydrazine

8‐Hydroxyquinoline‐7‐carboxaldehyde (8‐HQ‐7‐CA), Schiff‐base ligand 8‐hydroxyquinoline‐7‐carboxaldehyde benzoylhydrazone, and binuclear complexes [LnL(NO₃)(H₂O)₂]₂ were prepared from the ligand and equivalent molar amounts of Ln(NO₃)?6 H₂O (Ln=La³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Dy³⁺, Ho³⁺, Er³⁺, Yb³⁺, resp.). Ligand acts as dibasic tetradentates, binding to Ln^III through the phenolate O‐atom, N‐atom of quinolinato unit, and C?N and ? O? C?N? groups of the benzoylhydrazine side chain. Dimerization of this monomeric unit occurs through the phenolate O‐atoms leading to a central four‐membered (LnO)₂ ring. Ligand and all of the Ln^III complexes can strongly bind to CT‐DNA through intercalation with the binding constants at 10⁵–10⁶ M ^?1. Moreover, ligand and all of the Ln^III complexes have strong abilities of scavenging effects for hydroxyl (HO^.) radicals. Both the antioxidation and DNA‐binding properties of Ln^III complexes are much better than that of ligand.     

Guanosine Nucleolipids: Synthesis,Characterization, Aggregation and X‐Ray Crystallographic Identification of Electricity‐Conducting G‐Ribbons

The lipophilization of β‐d ‐riboguanosine ( 1 ) with various symmetric as well as asymmetric ketones is described (→ 3a – 3f ). The formation of the corresponding O‐2′,3′‐ketals is accompanied by the appearance of various fluorescent by‐products which were isolated chromatographically as mixtures and tentatively analyzed by ESI‐MS spectrometry. The mainly formed guanosine nucleolipids were isolated and characterized by elemental analyses, ¹H‐, ¹³C‐NMR and UV spectroscopy. For a drug profiling, static topological polar surface areas as well as ¹⁰logP_OW values were calculated by an increment‐based method as well as experimentally for the systems 1‐octanol‐H₂O and cyclohexane‐H₂O. The guanosine‐O‐2′,3′‐ketal derivatives 3b and 3a could be crystallized in (D₆)DMSO – the latter after one year of standing at ambient temperature. X‐ray analysis revealed the formation of self‐assembled ribbons consisting of two structurally similar 3b nucleolipid conformers as well as integrated (D₆)DMSO molecules. In the case of 3a ? DMSO, the ribbon is formed by a single type of guanosine nucleolipid molecules. The crystalline material 3b ? DMSO was further analyzed by differential scanning calorimetry (DSC) and temperature‐dependent polarization microscopy. Crystallization was also performed on interdigitated electrodes (Au, distance, 5 μm) and visualized by scanning electron microscopy. Resistance and amperage measurements clearly demonstrate that the electrode‐bridging 3b crystals are electrically conducting. All O‐2′,3′‐guanosine ketals were tested on their cytostatic/cytotoxic activity towards phorbol 12‐myristate 13‐acetate (PMA)‐differentiated human THP‐1 macrophages as well as against human astrocytoma/oligodendroglioma GOS‐3 cells and against rat malignant neuroectodermal BT4Ca cells.     

Asymmetric Allylation of α‐Ketoester‐Derived N‐Benzoylhydrazones Promoted by Chiral Sulfoxides/N‐Oxides Lewis Bases: Highly Enantioselective Synthesis of Quaternary α‐Substituted α‐Allyl‐α‐Amino Acids

Chiral sulfoxides/N‐oxides (R)‐ 1 and (R,R)‐ 2 are effective chiral promoters in the enantioselective allylation of α‐keto ester N‐benzoylhydrazone derivatives 3a , 3b , 3c , 3d , 3e , 3f , 3g to generate the corresponding N‐benzoylhydrazine derivatives 4a , 4b , 4c , 4d , 4e , 4f , 4g , with enantiomeric excesses as high as 98%. Representative hydrazine derivatives 4a , 4b were subsequently treated with SmI₂, and the resulting amino esters 5a , 5b with LiOH to obtain quaternary α‐substituted α‐allyl α‐amino acids 6a , 6b , whose absolute configuration was assigned as (S), with fundament on chemical correlation and electronic circular dichroism (ECD) data. Chirality 25:529–540, 2013. © 2013 Wiley Periodicals, Inc.     

6‐Methyl 3‐chromonyl 2,4‐thiazolidinedione/2,4‐imidazolidinedione/2‐thioxo‐imidazolidine‐4‐one compounds: novel scavengers of reactive oxygen species

The benefits of antioxidants on human health are usually ascribed to their potential ability to remove reactive oxygen species providing protection against oxidative stress. In this paper the free radicals scavenging activities of nine 6‐methyl 3‐chromonyl derivatives (CMs) were evaluated for the first time by the chemiluminescence, electron paramagnetic resonance, spin trapping and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH^?) methods. The total antioxidant capacity was also measured using a ferric‐ferrozine reagent. Compounds having a hydrogen atom at the N3‐position of the β‐ring were effective in quenching CL resulted from the KO₂/18‐crown‐6‐ether system (a source of superoxide anion radical, ) in a dose‐dependent manner over the range of 0.05–1 mmol/L [IC₅₀ ranged from 0.353 (0.04) to 0.668 (0.05) mmol/L]. The examined compounds exhibited a significant scavenging effect towards hydroxyl radicals (HO^? HO^?), produced by the Fenton reaction, and this ranged from 24.0% to 61.0%, at the concentration of 2.5 mmol/L. Furthermore, the compounds examined were also found to inhibit DPPH^? and this ranged from 51.9% to 97.4% at the same concentration. In addition, the use of the total antioxidant capacity assay confirmed that CM compounds are able to act as reductants. According to the present study, CM compounds showed effective in vitro free radical scavenging activity and may be considered as potential therapeutics to control diseases of oxidative stress‐related etiology. Copyright © 2013 John Wiley & Sons, Ltd.     

Scavenging of reactive oxygen species by N‐substituted indole‐2 and 3‐carboxamides

Indole‐2 and 3‐carboxamides (IDs) are proposed to be selective cyclooxygenase inhibitors. Since cyclooxygenase‐1 may be involved in reactive oxygen species (ROS) production, we hypothesize that these indole derivatives have antioxidative properties. We have employed chemiluminescence (CL) and electron spin resonance (ESR) spin trapping to examine this hypothesis. We report here the results of a study of reactivity of 10 selected indole derivatives towards ROS. The following generators of ROS were applied: potassium superoxide (KO₂) as a source of superoxide radicals (O₂^·?), the Fenton reaction (Co‐EDTA/H₂O₂) for hydroxyl radicals (HO^·), and a mixture of alkaline aqueous H₂O₂ and acetonitrile for singlet oxygen (¹O₂). Hydroxyl radicals were detected as 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO) spin adduct, whereas 2,2,6,6‐tetramethyl‐piperidine (TEMP) was used as a detector of ¹O₂. Using the Fenton reaction, 0.5 mmol/L IDs were found to inhibit DMPO‐?H radical formation in the range 7–37%. Furthermore the tested compounds containing the thiazolyl group also inhibited the ¹O₂‐dependent TEMPO radical, generated in the acetonitrile + H₂O₂ system. About 20% inhibition was obtained in the presence of 0.5 mmol/L IDs. 1 mmol/L IDs caused an approximately 13–70% decrease in the CL sum from the O₂^·? generating system (1 mmol/L). The aim of this paper is to evaluate these indole derivatives as antioxidants and their abilities to scavenge ROS. Copyright © 2004 John Wiley & Sons, Ltd.     

Further crystallographic evidence of NH· · ·π (system) and CO· · ·π (system) interactions: The structures of bis(diarylhydrazonecarbonyl)methylene derivatives [{ArPhCNNH—C(O)}2CH2] (Ar = Ph, 2‐C5H4N, 2‐C4H3S)

In this study are reported the syntheses of three bis(diarylhydrazonecarbonyl)methylene derivatives [{ArPhCNNH C(O)}₂CH₂] [Ar = 2 C₅H₄N (5), C₆H₅ (6), and 2‐C₄H₃S (7)], obtained by condensation of corresponding hydrazones with carbon suboxide, C₃O₂. The solid‐state self‐assembly of these carbonyl derivatives, giving rise to polymeric and dimeric networks, is described. In the formation of these structural features, in addition to N—H· · ·OC intermolecular hydrogen bonds, stabilizing intramolecular NH· · · π (systems) and intermolecular CO· · ·π (systems) interactions also seem to play an important role. Solution ¹H‐nmr data of compounds 5–7 indicate that the polymeric and dimeric structures are not maintained in solution and show the occurrence of keto‐enolic equilibria. © 1999 John Wiley & Sons, Inc. Biopoly 49: 541–549, 1999     

Synthesis of some novel quinone diimine derivatives of benzo‐15‐crown‐5 for application in Hg2+ recognition

A series of novel fluoroionophore bearing derivatives of benzo‐15‐crown‐5 were synthesized by the amination of benzo‐15‐crown‐5 followed by condensation with different quinones in the presence of titanium tetrachloride (TiCl₄) and 1,4‐diazabicyclo‐[2.2.2]octane. The compounds were characterized by infrared, ¹H and ¹³C nuclear magnetic resonance, mass spectroscopy and elemental analysis. Absorption and fluorescence spectral characteristics of these compounds were studied. It was observed that the anthraquinone derivative was acting as an Hg²⁺ ion sensor. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis of Novel Chiral Sulfonamide‐Bearing 1,2,4‐Triazole‐3‐thione Analogs Derived from D‐ and L‐Phenylalanine Esters as Potential Anti‐Influenza Agents

Novel enantiopure 1,2,4‐trizole‐3‐thiones containing a benzensulfonamide moiety were synthesized via multistep reaction sequence starting with D‐phenylalanine methyl ester and L‐phenylalanine ethyl ester as a source of chirality. The chemical structures of all compounds were characterized by elemental analysis, UV, IR, ¹H NMR, ¹³C NMR, 2D NMR (HETCOR), and mass spectral data. All compounds were tested in vitro antiviral activity against a broad variety of DNA and RNA viruses and in vitro cytostatic activity against murine leukemia (L1210), human T‐lymphocyte (CEM) and human cervix carcinoma (HeLa) cell lines. Although enantiopure 1,2,4‐triazole‐3‐thione analogs in (R) configuration emerged as promising anti‐influenza A H1N1 subtype in Madin Darby canine kidney cell cultures (MDCK), their enantiomers exhibited no activity. Especially compounds 18a , 21a , 22a , 23a , and 24a (EC₅₀: 6.5, 6.1, 2.4, 1.6, 1.7 μM, respectively) had excellent activity against influenza A H1N1 subtype compared to the reference drug ribavirin (EC₅₀: 8.0 μM). Several compounds have been found to inhibit proliferation of L1210, CEM and HeLa cell cultures with IC₅₀ in the 12–53 μM range. Compound 5a and 27a in (R) configuration were the most active compounds (IC₅₀: 12–22 μM for 5a and IC₅₀: 19–23 μM for 27a ). Chirality 28:495–513, 2016. © 2016 Wiley Periodicals, Inc.     

Influence of substituents on conformational preferences of helix foldamers of γ‐dipeptides

Conformational preferences of 9‐ and 14‐helix foldamers have been studied for γ‐dipeptides of 2‐aminocyclohexylacetic acid (γAc₆a) residues such as Ac‐(γAc₆a)₂‐NHMe ( 1 ), Ac‐(C^α‐Et‐γAc₆a)₂‐NHMe ( 2 ), Ac‐(γAc₆a)₂‐NHBn ( 3 ), and Ac‐(C^α‐Et‐γAc₆a)₂‐NHBn ( 4 ) at the M06‐2X/cc‐pVTZ//M06‐2X/6‐31 + G(d) level of theory to explore the influence of substituents on their conformational preferences. In the gas phase, the 9‐helix foldamer H9 and 14‐helix foldamer H14‐z are found to be most preferred for dipeptides 2 and 4 , respectively, as for dipeptides 1 and 3 , which indicates no remarkable influence of the C^α‐ethyl substitution on conformational preferences. The benzyl substitution at the C‐terminal end lead H14‐z to be the most preferred conformer for dipeptides 3 and 4 , whereas it is H9 for dipeptides 1 and 2 , which can be ascribed to the favored C? H···π interactions between the cyclohexyl group of the first residue and the C‐terminal benzyl group. There are only marginal changes in backbone structures and the distances and angles of H‐bonds for all local minima by C^α‐ethyl and/or benzyl substitutions. Although vibrational frequencies and intensities of the dipeptide 4 calculated at both M06‐2X/6‐31 + G(d) and M05‐2X/6‐31 + G(d) levels of theory are consistent with observed results in the gas phase, H14‐z is predicted to be most preferred by ΔG only at the former level of theory. Hydration did not bring the significant changes in backbone structures of helix foldamers for both dipeptide 1 and 4 . It is expected that the different substitutions at the C‐terminal end lead to the different helix foldamers, which may increase the resistance of helical structures to proteolysis and provide the more surface to the helical structures suitable for molecular recognition. © 2014 Wiley Periodicals, Inc. Biopolymers 101: 1077–1087, 2014.     

Melanogenesis‐Inhibitory Activities of Isomeric C‐seco Limonoids and Deesterified Limonoids

Treatment of eight C‐seco limonoids including six of salannin‐type, 1 – 6 , and two of nimbin‐type, 7 and 8 , with a combination of BF₃ · Et₂O and iodide ion yielded the isomeric C‐seco derivatives, i.e., six isosalannins, 1a – 6a , and two isonimbins, 7a and 8a , respectively. Ohchinin ( 1 ) was further subjected to LiAlH₄ reduction which yielded a deesterified trihydroxy limonoid, nimbidinol ( 9 ). In addition, ten limonoids including seven of azadirone‐type, 10 – 16 , and three of gedunin‐type, 17 – 19 , all of which possess no ester functionality in the molecule, were obtained from the neutral fraction of Azadirachta indica seed extract after alkaline hydrolysis. Among the above, twelve compounds, i.e., 1a – 4a , 6a , 9 , 13 – 16 , 18 , and 19 , were new compounds, and their structures were elucidated on the basis of extensive spectroscopic analysis and comparison with literature data. Upon evaluation of all these limonoids for their inhibitory activities against melanogenesis in B16 melanoma cells induced with α‐melanocyte‐stimulating hormone (α‐MSH), five structurally modified limonoids, 3‐deacetyl‐28‐oxosalannin ( 6a ), 9 , 17‐epi‐17‐hydroxynimbocinol ( 14 ), 17‐epi‐17‐hydroxy‐15‐methoxynimbocinol ( 15 ), and 7‐deacetyl‐17‐epinimolicinol ( 18 ), in addition to a natural limonoid, 1 , exhibited potent inhibitory activities with 26 – 66% reduction of melanin content at 100 μm concentration with almost no or low toxicity to the B16 melanoma cells (70 – 99% cell viability at 100 μm ).     

Syntheses and Antitumor Evaluation of C(6)‐Isobutyl‐ and C(6)‐Isobutenyl‐Substituted Pyrimidines,and Dihydropyrrolo[1,2‐c]pyrimidine‐1,3‐diones

A growing body of evidence supports that pyrimidine derivatives, in which the sugar residues have been replaced by acyclic side chains, might be developed as promising anticancer agents that interfere with tumor cell proliferation, survival, and metastatic formation. In this work, we prepared novel pyrimidines bearing i‐Bu (i.e., 3, 4 , and 7 – 9 ) and isobutenyl (i.e., 5 and 10 ) side chains at C(6) and examined their in vitro effects on tumor cell lines. The dihydropyrrolo[1,2‐c]pyrimidine‐1,3‐diones 6 and 11 were obtained as products of intramolecular cyclization, which occurred during the removal of Bn in 5 or MeO protecting groups in 10 . Fluorination of 3 with diethylaminosulfur trifluoride (DAST) and then dehydrohalogenation of the resulting fluorinated derivative 4 afforded 6‐isobut‐2′‐enyl pyrimidine derivative 5 with a C(2′)C(3′) bond. For the preparation of 6‐isobut‐1′‐en‐1‐yl pyrimidine 10 , a synthetic strategy involving acetylation of the 1,3‐diols was applied. Antitumor evaluation of compounds 3 – 11 showed that 2,4‐dimethoxypyrimidine containing 6‐[(1,3‐dibenzyloxy)‐2‐hydroxy]methyl side chain, 3 , exerted a strong antiproliferative effect on the studied tumor cell lines. Additionally, it was shown that the mechanism of antiproliferative effect of 3 in HeLa cells include early G2/M arrest and apoptosis, as well as a p53‐independent S‐phase arrest upon prolonged treatment.     

Claisen–Schmidt condensation: Synthesis of (1S,6R)/(1R,6S)‐2‐oxo‐N,4,6‐triarylcyclohex‐3‐enecarboxamide derivatives with different substituents in H2O/EtOH

A simple, green, and direct three‐component condensation of acetophenone, aromatic aldehydes with 3‐oxo‐N‐phenylbutanamide (acetoacetanilide) to generate some novel (1S,6R)/(1R,6S)‐2‐oxo‐N,4,6‐triarylcyclohex‐3‐enecarboxamide derivatives was carried out over K₂CO₃ (10 mol%) with high efficiency in water/ethanol as green solvent at room temperature. This protocol proceeded via Claisen–Schmidt condensation and Michael addition. The present methodology offers several advantages, such as short reaction time, high yield, more readily available and inexpensive materials, more environmentally friendly, no need for column chromatography, simple work‐up procedure, and the absence of volatile and hazardous organic solvents.     

Structures and luminescent sensors of mixed‐counterions based salen‐type lanthanide coordination polymers

Reactions of N,N′‐bis (salicylidene)‐1,2‐cyclohexanediamine (H₂L) with mixed lanthanide counterions of LnCl₃·6H₂O and Ln (NO₃)₃·6H₂O afford six H₂L lanthanide coordination polymers, e.g. {[Pr(H₂L)₂(NO₃)₂Cl]·2CH₂Cl₂}_n ( 1 ); {[Ln(H₂L)_1.5(NO₃)₃]₂·5CHCl₃·mCH₃OH}_n [Ln = Sm ( 2 ), Eu ( 3 ), Gd ( 4 ), Tb ( 5 ) and Yb ( 6 ); m = 1 ( 2 – 5 ); m = 0 ( 6 )]. X‐ray crystallographic analysis reveals that complex 1 exhibits three‐dimensional diamondoid topologic structure and complexes 2 – 6 are of two‐dimensional structure. Luminescent spectra show that complexes 1 and 6 have characteristic near‐infrared (NIR) emission of praseodymium (III) and ytterbium (III) ions and complexes 2 – 5 emit luminescence in the visible region. Complexes 3 and 6 reveal sensitive luminescence responses to formaldehyde.