BEDT–TTF charge-transfer salts: new structures,new functionalities

In the continuing search for new physical properties and combinations of properties in molecular materials, novel phenomena and structures are identified in three categories of TTF and BEDT–TTF (bis-ethylenedithiotetrathiafulvalene) charge-transfer salts with inorganic complex anions. When the anion is a 3d complex containing NCS^– and an aromatic donor, long range π–d ferrimagnetic order is established by donor-anion π–π overlap; when the anion is a tris-oxalato-metallate(III) complex, both normal state and superconducting behaviour are dramatically influenced by changing guest molecules in the lattice, while incorporating columns of crown ether and H₃O⁺/H₂O leads to metallic conductors that simultaneously transport protons. To cite this article: P. Day, C. R. Chimie 6 (2003).     

Synthesis of new α,α,β,β-tetrafluoroesters

Substituted phenyl iodides or diiodides reacted with ethyl iodotetrafluoroproponylate ICF₂CF₂CO₂Et, 1 in the presence of copper powder to give the coupled products 2 or 3 in good yields. Addition of 1 to ethylene and allyl acetate proceeded smoothly under thermal and radical conditions to give the corresponding adducts, which underwent elimination reaction to give β-vinyl and β-allyl α,α,β,β-tetrafluoroesters, CH₂CHCF₂CF₂CO₂Et, 4 and CH₂CHCH₂CF₂CF₂CO₂Et, 5, respectively. 1 also readily reacted with 1,5-hexadiene and 1-hexene with copper or palladium complex, followed by reduction to remove iodine to produce ω-alkenyl-α,α,β,β-tetrafluoroester CH₂CH(CH₂)₄CF₂CF₂CO₂Et 6 and α,α,β,β-tetrafluoroester C₄H₉CH₂CHICF₂CF₂CO₂Et.     

Toonapolyynes A–D,new polyynes from Toona ciliata

Abstract

Phytochemical investigation on the leaves and twigs of Toona ciliata has led to the isolation of four new polyynes (1–4) and two knowns (5 and 6). Their structures were determined by extensive spectroscopic analysis (MS, UV, IR, and NMR) and Mosher’s method. All compounds were evaluated for their inhibitory activities against HepG2 human tumor cell line but were inactive.     

Pycnalin, a new α-glucosidase inhibitor from Acer pycnanthum

A new compound, pycnalin (1), together with four known compounds, ginnalins A (2), B (3), C (4), and 3,6-di-O-galloyl-1,5-anhydro-D-glucitol (3,6-di-GAG) (5), were isolated from Acer pycnanthum. The structure of 1 was determined on the basis of 2D-NMR spectral data and synthesis of 1. Pycnalin (1) is the first 1,5-anhydro-D-mannitol linked to a gallic acid, while compounds 2-5 were 1,5-anhydro-D-glucitol linked to gallic acids. All compounds were tested in vitro for α-glucosidase inhibitory and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities. Pycnalin (1) exhibited moderate α-glucosidase inhibitory activity as well as free radical scavenging activity. Ginnalin A (2) and 3,6-di-GAG (5), which have two galloyl groups, exhibited potent α-glucosidase inhibition, compared to those of other compounds 1, 3, and 4 containing a galloyl group. These results suggest that α-glucosidase inhibition is influenced by the number of galloyl groups.     

Two new lanthanide–radical complexes: synthesis,structure, and magnetic properties

Two new lanthanide–radical complexes, [Tb(hfac)₃(EtVNIT)₂] (1) and [Dy(hfac)₃(EtVNIT)₂] (2) (EtVNIT?=?2-(4′-ethoxy-3′-methoxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, hfac?=?1,1,1,5,5,5-hexafluoroacetylacetonate), were synthesized; both display radical–Ln(III)–radical (Ln=Tb (1), Dy (2)) tri-spin structures. Magnetic studies reveal that interactions between the lanthanide ions and radicals are ferromagnetic.     

A convenient synthesis of α',β-diamino-α,α-difluoroketones,new dipeptide isosteres

A convenient and versatile synthesis of α′,β-diamino-α,α-difluoroketones is described. These compounds represent a new class of true isosteres useful for the design of serine protease inhibitors.     

A comparative study of fragment screening methods on the p38�� kinase: new methods, new insights

The stress-activated kinase p38α was used to evaluate a fragment-based drug discovery approach using the BioFocus fragment library. Compounds were screened by surface plasmon resonance (SPR) on a Biacore(?) T100 against p38α and two selectivity targets. A sub-set of our library was the focus of detailed follow-up analyses that included hit confirmation, affinity determination on 24 confirmed, selective hits and competition assays of these hits with respect to a known ATP binding site inhibitor. In addition, functional activity against p38α was assessed in a biochemical assay using a mobility shift platform (LC3000, Caliper LifeSciences). A selection of fragments was also evaluated using fluorescence lifetime (FLEXYTE(?)) and microscale thermophoresis (Nanotemper) technologies. A good correlation between the data for the different assays was found. Crystal structures were solved for four of the small molecules complexed to p38α. Interestingly, as determined both by X-ray analysis and SPR competition experiments, three of the complexes involved the fragment at the ATP binding site, while the fourth compound bound in a distal site that may offer potential as a novel drug target site. A first round of optimization around the remotely bound fragment has led to the identification of a series of triazole-containing compounds. This approach could form the basis for developing novel and active p38α inhibitors. More broadly, it illustrates the power of combining a range of biophysical and biochemical techniques to the discovery of fragments that facilitate the development of novel modulators of kinase and other drug targets.     

Stellarins F and G, two new cyclopeptides from Stellaria yunnanensis

In the previous papers,we reported the structural elucidation of stellarins A-E,fivenew cyclopeptides from the fresh roots of Stellaria yunnanensis Franch.Further chemical study on this plant led to the isolation of two other new cyclopeptides named stellarins F(l) and G(2).By a combination of 2D-NMR,enzymatic degradation and FABMS,their structures were established to be cyclo(Gly-Ala-Gly-Ser-Pro-Trp-Phe-Pro) and cyclo(Gly-Ala-Tyr-Leu-Ala),respectively.     

Two new α,β-unsaturated butyrolactone derivatives from Pleione bulbocodioides

Two newα,β-unsaturated butyrolactone derivatives,4-(4″-hydroxybenzyl)-3-(3′-hydroxy-phenethyl)furan-2(5H)-one(1)and 3-(3′-hydroxyphenethyl)furan-2(5H)-one(2),together with one known phenolic compound(3),were isolated from the tubers of Pleione bulbocodioides(Franch.)Rolfe.Their structures were elucidated by analysis of spectroscopic data.     

Briaviodiols B–E,new anti-inflammatory hydroperoxyfurancembranoids from Briareum violaceum

Four new hydroperoxyfurancembranoids, briaviodiols B–E (1–4), were obtained from an octocoral identified as Briareum violaceum. The structures of cembranoids 1–4 were established by using spectroscopic methods and comparing the spectroscopic data with those of known related analogues. Compounds 1, 3, and 4 were found to exhibit significant in vitro anti-inflammatory activity in LPS-induced RAW 264.7 macrophage cells by inhibiting the expression of iNOS protein.     

Fusarielin E, a new antifungal antibiotic from Fusarium sp.

A new antifungal antibiotic,fusarielin E,was isolated from the marine-derived fungus Fusarium sp.Its structure was established on the basis of various NMR spectroscopic analyses and HR-FAB-MS.Fusarielin E displayed significant biological activity against Pyricularia oryzae.     

“Anhydrolycaconitine”, a new diterpene alkaloid fromAconitum septentrionale K

A new alkaloid, anhydrolycaconitine (C₃₆H₄₆N₂O₉), was isolated from roots ofAconitum septentrionale K. Based on the results of¹H and¹³C NMR and IR spectroscopy and mass spectrometry of the alkaloid and the product of its alkaline hydrolysis and on the data of X-ray diffraction analysis of the hydrolysis product, the structure of 1α, 6β, 14α, 16β-tetramethoxy-7-oxo-18-succinylanthranoyloxy-17-(7→8)abeo-aconane was assigned to anhydrolycaconitine. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1640–1644, September, 2000.     

“Multitracer” a new tracer technique — Its principle,features, and application

We established Multitracer, a new versatile radiotracer technique, for simultaneous tracing of a number of elements in various chemical, environmental, and biological systems. Metal foil targets (typically Au, Ag, Ge, Cu and Fe) are irradiated with C, N, or O ions accelerated up to 135 MeV/nucleon by RIKEN Ring Cyclotron. Radiochemical procedures have been developed to remove the target material leaving the nuclides as Multitracer solutions containing various radionuclides of Be, Na, Mg, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Te, I, Ba, Ce, Pm, Eu, Gd, Tb, Tm, Yb, Lu, Hf, W, Re, Os, Ir, Pt, and Hg. Multitracers enable efficient tracing of a number of elements, and comparison of their behavior under strictly identical experimental conditions. Such features will be demonstrated by means of an example of application to a model experiment for the study of removal mechanism of various elements from the ocean.     

Synthesis, characterization, and biological evaluation of new N-glycosides derived from O-pivaloylated β-d-glucopyranosylamine

The novel synthesis of N-(2,3,4,6-tetra-O-pivaloyl-??-d-glucopyranosyl) benzo[d] oxazol-2-amine 4 was described in this study. The new compounds N-arylthioureas 3a-c and 4, along with a series of glucose-modified imines 5a-g, were evaluated for their antitumor activity against human myeloid leukemia cell lines (HL-60 cells), gastric carcinoma (BGC-823 cells), liver carcinoma (Bel-7402 cells), and oral carcinomas (KB cells). The antibacterial potency of these compounds was also determined using an inhibition zone diameter test. Although none of the compounds were active against human cancer cells, compound 4 was found to be the most active compound against Escherichia coli.     

A new general, practical and enantioselective synthesis of α-amino acids

In recent years, considerable efforts have been expended to the development ofenantioselective synthesis of α-amino acids and the use of α-amino acids as chiralbuilding blocks for the synthesis of complex molecules. Numerous unnatural aminoacids which are often the characteristic units of biologically active peptides, have alsobeen discovered. Herein we describe a convenient and general access to natural andunnatural α-amino acids which are based on the use of the chiral building blocks,(S)-1a-e and (R)-1a-e from kinetic resolution of α-furfuryl amines (Scheme 1).     

Munronoids A–J,ten new limonoids from Munronia unifoliolata Oliv

Ten new limonoids, named munronoids A–J (1–10), were isolated from Munronia unifoliolata Oliv. These limonoids involved in the skeletons of peieurianin, evodulone, euphane, and havanensin-types of limonoids, and their structures were established on the basis of spectroscopic data and X-ray crystallographic method. Compounds 1 and 2 were rollout of the conjugated Δ^8,30 and Δ^14,15 double bonds in peieurianin-type, 3–6 featuring a γ-lactone ring instead of the β-substituted furan ring were found in the evodulone-type for the first time. The insecticidal and anti-TMV activities of compounds 1–10 were also evaluated.     

A new pyridine synthesis starting from α, β-unsaturated carbonyl compounds

A new and mild synthetic method of substituted pyridines from α, β-unsaturated carbonyl compounds through a sequence involing (1) 1, 4-conjugate addition of thiophenol (2) condensation with a methylene ketone (3) Pummerer rearrangement to an unsaturated 1, 5-dicarbonyl compound (4) treatment with ammonia is described.     

Synthesis of some new α,α-dioxoketene-N,S- and -N,N-acetals derived from secondary aliphatic amines

A total of 11 new α,α-dioxoketene- N,S -acetals (2a–2k) and two new α,α-dioxoketene- N,N -acetals (3j and 3k) have been synthesised by treating 3-[bis(methylthiol)methylene]pentane-2,4-dione (1) with increasing mole ratios of secondary aliphatic amines at room temperature, in either toluene or ethanol. Eight non-cyclic N -methylalkyl and N -ethylalkyl amines and the azacyclopentane of pyrrolidine yielded exclusively mono-substituted N,S -acetals (2a–2i), while the azacyclohexanes of piperidine and morpholine yielded the mono-substituted N,S -acetals 2j and 2k and the double-substituted N,N -acetals 3j and 3k. The conversion yields for the reactions in ethanol are considerably higher than those in toluene. Furthermore, the secondary aliphatic amines with an N -methylalkyl moiety, which have one primary α-carbon and less steric crowding around the nucleophilic nitrogen, appear to be more reactive towards 1 than those with the N -ethylalkyl group, which have two primary α-carbons; further, the latter amines are more reactive than the amines with secondary α-carbons.     

Iridium-catalyzed asymmetric hydrogenation of β-keto esters with new phenethylamine-derived tridentate P,N,N-ligands

A new class of phenethylamine-derived tridentate P,N,N-ligands has been successfully developed. These ligands exhibited good performance in the Ir-catalyzed asymmetric hydrogenation of β-keto esters, affording the corresponding β-hydroxy esters in moderate to good enantioselectivities.