Network dimensionality and ligand flexibility in lanthanide terephthalate hydrates

Various lanthanide open framework materials incorporating the terephthalate (TP) entity were prepared using hydrothermal synthesis methods at a moderate temperature of 170 °C. The compounds Nd₂(TP)₃(H₂O)₄(1), Er₂(TP)₃(H₂O)₄(2), Yb₂(TP)₃(H₂O)₂(3), Yb₂(TP)₃(H₂O)₆(4), and Yb₂(TP)₃(H₂O)₈·2H₂O (5), were characterized by single crystal structural analysis and FT-IR spectroscopy. While compounds 1 and 2 have been reported before on the basis of powder X-ray diffraction, the structural characterization of any ytterbium terephthalate species is unprecedented. Compounds 1-5 crystallize in triclinic settings with space group P-1. The compounds are compared with their previously reported Er and Tb-counterparts and the reduction of the dimensionality of the resulting networks from 3D over 2D to 1D with increasing level of hydration is discussed. Compounds 1, 2, and 3 with the lowest water content assemble in three-dimensional network lattices. Compounds 4 and 5, however, form 2D layered systems and 1D rod like chains, respectively, which are held together by hydrogen bonds originating from coordinating H₂O. The crystal lattices of the 3D networks experience higher levels of tension as can be seen by increasing out-of-plane torsion with regard to the terephthalate carboxylate groups. Moreover, there seems to be a correlation between the level of strain on the aromatic ligands and the reduction of the number of carboxylate oxygen atoms that are part of the coordination polyhedra.     

Pyrazolyl iron, cobalt, nickel, and palladium complexes: synthesis, molecular structures, and evaluation as ethylene oligomerization catalysts

Reactions of [2-(3,5-dimethyl-pyrazol-1-yl)-ethanol] (L1) and [1-(2-chloro-ethyl)-3,5-dimethyl-1H-pyrazole] (L2) with Fe(II), Co(II), Ni(II), and Pd(II) salts gave the complexes [(L1)₂FeCl₂] (1), [(L1)₂CoCl₂] (2), [(L1)₂NiBr₂] (3), [(L1)₂Pd(Me)Cl] (5), [(L2)₂CoCl₂] (6), and [(L2)₂NiBr₂] (7). Whereas L2 behaves as a monodentate ligand, L1 can behave as either a monodentate or bidentate ligand depending on the nature of the metal centre. For palladium, L1 is monodentate in the solid state structure of 5 but bidentate in the structure of 4, obtained during attempts to crystallize 3. While the activation of iron, cobalt and palladium complexes with EtAlCl₂ did not produce active ethylene oligomerization catalysts, the nickel complexes 3 and 7 produced active ethylene oligomerization catalysts. Activities as high as 4329 kg/mol Ni h were obtained. Catalyst 3 produced mainly butenes (57%) and hexenes (43%); of which a combined 20% were converted to Friedel-Crafts alkylated-toluene. Catalyst 7, on other hand, produced mainly butenes (90%) and small amounts of hexenes (10%) which were then completely converted to the corresponding Friedel-Crafts alkylated-toluene products. This difference in product distribution in catalysis performed by complexes 3 and 7 is indicative of the role of the OH functionality in L1 on the EtAlCl₂ co-catalysts.     

Synthesis, conformation and PKC isozyme surrogate binding of indolinelactam-Vs, new conformationally restricted analogues of (−)-indolactam-V

New conformationally restricted analogues of tumor promoter (−)-indolactam-V (1), indolinelactam-Vs (8, 11) and their hexyl derivatives at position 1 or 7 (9, 10, 12, 13), were synthesized from 1. (3R)-Indolinelactam-V (8) adopted a conformation similar to the twist form of 1 with a cis amide, while the conformation of (3S)-indolinelactam-V (11) was close to that of the sofa form of 1 with a trans amide. 7-Hexyl derivatives of 8 and 11 (10, 13) showed binding affinities for C1 domains of protein kinase C (PKC) isozymes compared to 1, but exhibited little selectivity among these PKC isozymes. However, introduction of the hexyl group at position 1 of 8 and 11 significantly enhanced their binding selectivity for novel PKC isozymes. The best selectivity for novel PKC isozymes was observed in (3S)-1-hexylindolinelactam-V (12) with a sofa-like conformation. These results suggest that a sofa-restricted analogue of 1 with a hydrophobic chain at an appropriate position would be a promising lead for designing agents with a high selectivity for novel PKC isozymes.     

Chaxines B, C, D, and E from the edible mushroom Agrocybe chaxingu

Four novel compounds, chaxines B (1), C (2), D (3), and E (4), were isolated from an edible mushroom Agrocybe chaxingu. The structures of 1-4 were determined by the interpretation of spectroscopic data. Compounds 1 and 2 suppressed the formation of osteoclast.     

New phlegmarane-type, cernuane-type, and quinolizidine alkaloids from two species of Lycopodium

Two new phlegmarane-type alkaloids, cermizines A (1) and B (2), three new quinolizidine alkaloids, cermizine C (3) and senepodines G (4) and H (5), and a new C₁₆N₂ type alkaloid consisting of a quinolizidine and a piperidine ring, cermizine D (6), as well as two new cernuane-type alkaloids, cernuine N-oxide (7) and lycocernuine N-oxide (8), have been isolated together with cernuine (9) and lycocernuine (10) from the club moss Lycopodium cernuum and L. chinense. The relative stereochemistry of 1-4 and 6, and the absolute stereochemistry of 5, 7, and 8 were elucidated by combination of NOESY correlations, modified Mosher's method, chemical transformations, and computational methods. Cermizine D (6) might be a biosynthetic intermediate of cernuane-type alkaloids such as 7-10.     

Briarenolides A-C, briarane diterpenoids from the gorgonian coral Briareum sp.

Chemical investigation on the gorgonian coral Briareum sp. has led to the isolation of six oxygenated briaran diterpenes 1-6, including three new compounds briarenolides A-C (1-3). The structures of 1-3 were determined on the basis of extensive spectroscopic analysis and by comparison of their spectral data with those of related metabolites. Among these metabolites, 1 and 2 are rarely found 9-ketobriaranes. Also, 1 is the first briarane derivative possessing a 20-hydroxy group.     

Pyridine mediated supramolecular assemblies of 3,5-dinitro substituted benzoic acid, benzamide and benzonitrile

Synthesis and characterization of molecular assemblies of pyridine adducts, 1a, 2a and 3a, of 3,5-dinitrobenzoic acid, 1, 3,5-dinitrobenzamide, 2 and 3,5-dinitrobenzonitrile, 3, respectively, have been reported. All these adducts were obtained by crystallization of 1, 2 and 3 from pyridine. However, crystallization of 1 from pyridine in the presence of benzene resulted in the formation of a pyridinium adduct, 1b, along with a water molecule. All the adducts crystallize in a 1:1 molecular ratio except 1a, which forms a 1:2 adduct, as characterized by single crystal X-ray diffraction method. The adducts crystallize in different space groups—1a, orthorhombic, Pna2₁; 1b, monoclinic, P2₁; 2a, monoclinc, C2/c; 3a, triclinic, . In two-dimensional arrangement, 1a, 1b and 3a form sheet structures. In 1a, within the two-dimensional sheets, large cavities are formed, which are occupied by pyridine molecules. In 1b, the sheets are catenated to form a chicken-wire network. However, 2a formed a crossed ribbon packing pattern with empty channels in the three-dimensional structure.     

Syntheses, crystal structures, and electrochemical properties of multi-ferrocenyl resorcinarenes

Tetraaryl and tetraferrocenyl resorcinarenes 1a-1c have been synthesized by the HCl-catalyzed condensation of resorcinol with aromatic aldehydes or ferrocenecarbaldehyde, which were fully alkylated with ethyl α-chloroacetate to give the activated ethyl resorcinarylacetates 2a-2c. Reaction of 2a-2c with hydrated hydrazine yielded the resorcinarene acylhydrazine derivatives 3a-3c, from which the multi-ferrocenyl functional groups were selectively and efficiently introduced on the upper rim, or on the lower rim, or both on the upper and lower rims of resorcinarenes 4a-4c and calixarenes 4d-4f based upon the condensation reactions of acylhydrazones with ferrocenecarboxaldehyde.     

Cobaloximes with mixed dioximes having C and S side chains: Synthesis, structure and reactivity

Ten mixed dioxime complexes RCo(L)(dmgH)Py [R = Cl, Me, Et, Bu, Benzyl] [L = dSPhgH (1-5) and dSEtgH (6-10)] have been synthesized and characterized by NMR. Formation of 1 and 6 is very fast and takes only 5 and 15 min in ethanol. Molecular oxygen insertion in 5 and 10 is monitored and forms mixture of products within 5 min. The crystal structure of 1, 4, 5, 6, 8 and 10 is reported. Benzyl ring is oriented over dmgH wing in both 5 and 10 and has a weak C-H…π interaction (3.33 Å and 3.22 Å) and this causes high upfield shift of the dmgH protons. Electrochemical study on 1, 4, 5, 6, 8 and 10 is also reported. Because of increased electron donation by SEt group, 6 is more difficult to reduce than 1.     

Synthesis, characterization, and derivatization of some novel types of fluorinated mono- and bis-imidazolidineiminothiones with antitumor, antiviral, antibacterial, and antifungal activities

A series of thirty eight novel imidazolidineiminothiones (6a-g, 10a-h, 13a,b, 15a-d, and 16a), 5-thioxoimidazolidine-2,4-diones (7a-d, 11a-e, 14a,b, and 16b), and bis-imidazolidineiminothiones (17-20) with various fluorinated aromatic substituents at N-(1) and N-(3) were prepared in 75-85% yields. The imidazolidineiminothiones were synthesized from fluorinated N-arylcyanothioformanilides and substituted aromatic isocyanates, and by the reactions of fluorinated aromatic isocyanates with fluorinated and non-fluorinated aromatic N-arylcyanothioformanilides. Subsequent hydrolysis of selected products produced the corresponding 5-thioxoimidazolidine-2,4-diones. Preliminary screening of several compounds against Ehrlich ascites carcinoma (EAC) cells indicated that 6f and 16a were the most active (90% and 80% inhibition, respectively). Further evaluation for cytotoxicity against other tumor cell lines gave IC₅₀ values ranging from 0.67 to 3.83 μg/mL, where compounds 15a and 16a were markedly active against all cell lines. This highlights the synergistic effect of the suitably positioned fluorinated substituents on N-(1) and N-(3) of the imidazolidineiminothiones. Compounds 6a,e-g, 10a-c, 13b, 15a-d, and 17-20 were tested against microbial organisms (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhi, and Sarcina lutea), and fungal strains (Candida albicans, Aspergillus niger, and Aspergillus flavus). Whereas compound 6a exhibited the highest antibacterial activity against Gram positive and Gram negative bacteria, 13b displayed the strongest antifungal activity against all fungal strains, reaching as high as 30 mm. Finally, 15a,b,d were subjected to in vitro testing of antiviral activity against hepatitis A virus (HAV), human herpes simplex virus 1 (HSV1), and Coxsackie B4 (COxB4) viral strain, where 15b was the most effective, reducing virus plaque count of HSV1 and COxB4 by 50% and 60%, respectively.     

Isolation, structural elucidation, and chemical transformation of interconvertible 8,12-hemiketal germacranolide sesquiterpenoids from Salvia castanea Diels f. tomentosa Stib.

From the aerial parts of Salvia castanea Diels f. tomentosa Stib., four new hemiketal germacranolide sesquiterpenoids, castanins C-F (1-4), were obtained as two pairs of interconvertible forms along with their acetates, 5 and 6. Their structures were elucidated by spectroscopic methods and X-ray analysis of the uninterconvertible isomeric acetates, 5 and 6. The computational study explained that the ratios of 1 and 2, 3 and 4, and their acetates (5 and 6) in the mixtures were 1:1, 1:2, and 1:3, respectively. In addition, the semisynthesis of castanins C (1) and D (2) was conducted by the photooxidation of castanin B (8), the major constituent of this plant. Compounds 5, 6, and 8 were also tested for their inhibitory activity toward MCF-7, HeLa, and HepG2 cell lines.     

Total synthesis of (+)-epiepoformin, (+)-epiepoxydon and (+)-bromoxone employing a useful chiral building block, ethyl (1R,2S)-5,5-ethylenedioxy-2-hydroxycyclohexanecarboxylate

Enantioselective total synthesis of (+)-epiepoformin 1, (+)-epiepoxydon 2 and (+)-bromoxone 3 using a chiral building block, ethyl (1R,2S)-5,5-ethylenedioxy-2-hydroxycyclo- hexanecarboxylate 6, is described. Since the synthesis afforded intermediates 18, 2 and 25, it accomplished a formal synthesis of (−)-theobroxide 19, (−)-phyllostine 22, (+)-herveynone 27 and (−)-asperpentyn 28. The usefulness of 6 for the synthesis of natural epoxycyclohexene derivatives was demonstrated.     

Daphniglaucins D-H, J, and K, new alkaloids from Daphniphyllum glaucescens

Five new fused-hexacyclic alkaloids, daphniglaucins D (1), E (2), F (3), G (4), and H (5), and two new yuzurimine-type alkaloids, daphniglaucins J (6) and K (7), have been isolated from the leaves of Daphniphyllum glaucescens, and the structures and relative stereochemistry were elucidated on the basis of spectroscopic data and chemical means.     

2-(1-Isopropyl-2-benzimidazolyl)-6-(1-aryliminoethyl)pyridyl transition metal (Fe, Co, and Ni) dichlorides: Syntheses, characterizations and their catalytic behaviors toward ethylene reactivity

A series of 2-(1-isopropyl-2-benzimidazolyl)-6-(1-aryliminoethyl)pyridyl metal complexes [iron (II) (1a-6a), cobalt (II) (1b-6b) and nickel (II) (1c-6c)] were synthesized and fully characterized by elemental and spectroscopic analyses. Single-crystal X-ray diffraction analyses of five coordinated complexes 5a, 3b, 5b, 1c and 2c reveal 5a and 5b as distorted trigonal-bipyramidal geometry, and 3b, 1c and 2c as distorted square pyramidal geometry. All complexes performed ethylene reactivity with the assistance of various organoaluminums. The iron complexes displayed good activities in the presence of MAO and MMAO. Upon activated by Et₂AlCl, the cobalt analogues showed moderate ethylene reactivity, while the nickel analogues exhibited relatively higher activities.     

Three new sulfur-containing alkaloids, polycarpaurines A, B, and C, from an Indonesian ascidian Polycarpa aurata

Three new sulfur-containing alkaloids, polycarpaurines A (1), B (2), and C (3) were isolated from the tropical ascidian Polycarpa aurata collected in Indonesia, together with six known compounds (4-9). The structures of new compounds were assigned on the basis of their spectral data. Compounds 1, 3, 4, and 8 inhibited colony formation of Chinese hamster V79 cells with EC₅₀ values of 6.8, 8.6, 3.8, and 10 μM, respectively. Compounds 2 and 7 showed modest activity against V79 cells (EC₅₀>10 μM).     

Briaexcavatins A and B, novel briaranes from the octocoral Briareum excavatum

Two novel briaranoidal derivatives, designated as briaexcavatins A (1) and B (2), along with two known metabolites, excavatolides B and C (3 and 4), were isolated from the octocoral Briareum excavatum. Both compounds 1 and 2 possess unprecedented 5,6-epoxy moiety in the 10-membered ring. Diterpenoid 1 possesses a novel pentacyclic skeleton with a ε-lactone. The structures of diterpenoids 1 and 2 were elucidated by interpretation of spectral data and the absolute stereochemistry was established by application of modified Mosher’s method on 3.     

Lissoclibadins 1-3, three new polysulfur alkaloids, from the ascidian Lissoclinum cf. badium

Three new polysulfur alkaloids, lissoclibadins 1 (1)-3 (3), were isolated from the ascidian Lissoclinum sp. (cf. L. badium Monniot, F. and Monniot, C., 1996). The structures of 1-3 were assigned on the basis of their spectral data, and the computational modeling study was utilized for 1. Compound 1 had a trimeric structure of three identical aromatic anime moieties connected through two sulfide and a disulfide bonds. Compounds 2 and 3 were dimeric structures of the same unit as that of 1 connected through a sulfide and disulfide bonds (2) and two sulfide bonds (3). Compounds 1 and 2 inhibited the growth of the marine bacterium Ruegeria atlantica (15.2 mm at 20 μg/disk and 12.2 mm at 5 μg/disk, respectively) and 2 showed antifungal activity to Mucor hiemalis (13.8 mm at 50 μg/disk). Compounds 1-3 were cytotoxic against HL-60 (IC₅₀=0.37, 0.21, and 5.5 μM, respectively).     

1,6- and 1,7-regioisomers of dinitro- and diamino-substituted perylene bisimides: synthesis,photophysical and electrochemical properties

1,6- and 1,7-regioisomers of dinitro- (1,6-3 and 1,7-3) and diamino-substituted perylene bisimides (1,6-1 and 1,7-1) were synthesized. The regioisomers 1,6-3 and 1,7-3 were successfully separated by high performance liquid chromatography and characterized by 500 MHz ¹H NMR spectroscopy. Subsequently, the reduction of 1,6-3 and 1,7-3 afforded the corresponding diaminoperylene bisimides 1,6-1 and 1,7-1, respectively. This is the first time 1,6-regioisomers of dinitro- and diamino-substituted perylene bisimides are obtained in pure form. The photophysical and electrochemical properties of 1,6-3 and 1,7-3 were found to be almost the same. However, the regioisomers 1,6-1 and 1,7-1 exhibit significant differences in their optical characteristics. The absorption spectrum of 1,6-1 covers a larger part of the visible region compared to that of 1,7-1. Upon excitation, 1,6-1 also show larger dipole moment change than that of 1,7-1. Time-dependent density functional theory calculations are reported on these dyes in order to rationalize their electronic structure and absorption spectra.     

Cespitulactams A, B, and C, three new nitrogen-containing diterpenes from Cespitularia taeniata May

Three new nitrogen-containing diterpenoids, designated cespitulactams A (1), B (2), and C (3), were isolated from Cespitularia taeniata May. Compounds 1-3 are novel structures having a phenylethyl amino side at C-10 and with an amide function at C-20. Their structures were determined on the basis of extensive spectroscopic analysis and chemical correlation. The cytotoxicity of 1 and its monoacetate (6) were also evaluated against human cancer cell lines.     

Structurally original oxathioethers macrocycles containing an exocyclic double-bond: synthesis,characterization, reactivity,and coordination

New oxathioethers macrocycles have been synthesized and characterized. Each macrocycle consists in structurally defined ether and thioether moieties and an exocyclic double-bond (2a–c) or a hydroxymethyl group (3a–c). Macrocycles (2a–c) have been synthesized by reaction of dianions of thioethers diols (1a–c) with 3-chloro-2-chloromethylprop-1-ene. Their hydroboration/oxidation led to corresponding primary alcohols (3a–c). Structures of compounds (2b) and (3a) have been determined by X-ray diffraction. The reactivity of the hydroxyl group allowed the preparation of oxathioethers macrocycles bearing a polyether chain or a benzyl group (4a,b) and the synthesis of new bicyclic sandwich-type compounds (5a,b). The ability of these functionalized macrocycles to coordinate to palladium has been investigated.