Two new ceramides from <Emphasis Type="Italic">Zephyranthes candida</Emphasis>

Two new ceramides were isolated from the bulbs of Zephyranthes candida. Their structures were established as (2S,3S,4R,13E)-1,3,4-trihydroxy-2-[(2′R)-2′-hydroxytetracosanoylamino]-13-octadecene, named zephyranamide A (1) and (2S,3S,4R)-1,3,4-trihydroxy-2-octacosanoylaminohexadecene, named zephyranamide B (2). The structures of the new compounds were elucidated by spectral techniques including ¹H NMR, ¹³C NMR, as well as HSQC, HMBC, DEPT, and COSY.     

Enantioselective Deprotonation of Cyclohexene Oxide to (R)-2-Cyclohexen-1-ol

The reaction of cyclohexene oxide with homochiral lithium amides, prepared from (S)-phenylglycine and (S)-valine has been studied and (R)-2-cyclohexen-1-ol 3 was prepared in a maximum of 72% ee. The optical purity was determined by ¹H NMR measurement of the α-methoxy-α-(trifluoromethyl)phenyl acetic acid (MTPA) derivative of the corresponding alcohol.     

The steric structure of multiflorine methylation products

Summary Multiflorine (1) — a minor lupine alkaloid — treated by methyl lithium or methyl magnesium iodide affords 4S-4-hydroxy-4-methyl-2,3-didehydrosparteine (2) and 2S-2-methyl-4-oxosparteine (3), respectively, as the dominating products. Their steric structure, determined by¹H and¹³C NMR techniques, points to stereospecific preferences of these reactions. The observed nucleophilic 1,2- and 1,4-additions indicate that regiospecificity of the action of MeLi or MeMgI on multiflorine is different from that of the so far known similar alkylation of other enamino ketones.

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Die räumliche Struktur von Methylierungsprodukten des Multiflorins

Zusammenfassung Multiflorin (1), ein Lupin-Nebenalkaloid, ergibt bei Umsetzung mit Methyllithium oder Methylmagnesiumiodid 4S-4-Hydroxy-4-methyl-2,3-didehydrospartein (2) und 2S-2-Methyl-4-oxospartein (3) als Hauptprodukte. Ihre NMR-spektroskopisch (¹H und¹³C) aufgeklärte räumliche Struktur weist auf eine Stereoselektivität der erwähnten Reaktionen hin. Die beobachteten nucleophilen 1,2- und 1,4-Additionen zeigen, daß sich die Regiospezifität der Einwirkung von MeLi oder MeMgl auf Multiflorin von jener bis jetzt bekannter Alkylierungen von Enaminoketonen unterscheidet.

     

SYNTHESIS OF ANELLATED ANHYDROPYRANOSES ON THE BASIS OF 1,6-ANHYDRO-3-DEOXY-4-METHYLSULFANYL-3-[(METHYLSULFANYL)METHYLENE]-β-D-ERYTHRO-HEXOPYRANOS-2-ULOSE

(Z)-1,6-Anhydro-3-deoxy-4-methylsulfanyl-3-[(methylsulfanyl)methylene]-β-D-erythro-hexopyranos-2-ulose (1) reacted with diethyl malonate, 1,3-diketones, N-aryl-3-oxobutyramides and dialkyl 3-oxoglutarate, respectively, in the presence of potassium carbonate and crown ether to yield diethyl 2-(1,6-anhydro-4-methylsulfanyl—D-arabino-hex-2-ulopyranos-3-ylmethylene) malonate (2), 1-{(1R,2S,8S,9R)-2-hydroxy-4-methyl-8-methylthio-3,11,12- trioxatricyclo7.2.1.0^2,7dodeca-4,6-dien-5-yl} ethanone (3), (1R,2S,12S,13R)-2-hydroxy-12-methylthio-3,15,16-trioxatetracyclo[11.2.1. 0^2,11. 0^4,9] hexadeca- 4(9),10-dien-8-one (4), (1R,8S,9R)-5-acetyl-3-aryl-8-methylthio-11,12-dioxa- 3-azatricyclo-[7.2.1.0^2,7]dodeca-2(7),5-dien-4-ones (5,6) and dialkyl (1R,8S,-9R)-4-hydroxy-8-methylthio-11,12-dioxatricyclo[7.2.1.0^2,7]dodeca-2(7),3,5-triene-3,5-dicarboxylates (7,8), respectively.     

Synthesis,characterization, CT-DNA binding and docking studies of novel selenated ligands and their palladium complexes

A novel selenated Schiff base (S) -L ¹ H has been synthesized from (2S)-1-(benzylselanyl)-3-phenylpropan-2-amine which upon reduction formed a reduced Schiff base (S) -L ² H . Palladium (II) complexes (S) -1 and (S) -2 of ligands (S) -L ¹ H and (S) -L ² H respectively were successfully synthesized. The structures of all four compounds were thoroughly identified by analytical and various spectroscopic techniques. The absolute molecular structures of the above two complexes were further confirmed by single crystal X-ray diffraction. Both (S) -L ¹ H and (S) -L ² H coordinated as monobasic ((S) -L ^1–2 ), chelating, tridentate (Se,N,O⁻) ligands resulting in the complexes of composition (S) - [PdCl( L ^1/2 )] [(S) -1/2 ]. In the crystals of complexes (S) -1 and (S) -2 , there were moderate to strong Se⋯O, CH⋯Cl and CH⋯O types of intermolecular secondary interactions. CT-DNA binding activity of these selenium-containing ligands and their palladium complexes bearing a Pd–Se bond have been evaluated for the first time by performing electronic absorption titration and fluorescence emission quenching using CT-DNA-EB and viscometric experiments. These ligands and complexes exhibited remarkable DNA binding activity as shown by their intrinsic DNA binding constants (K_b) and Stern–Volmer constants (K_sv) in the ranges 5.2–9.9 × 10⁴ and 3.6–4.7 × 10⁴, respectively. The viscosity of CT-DNA decreases with increasing concentration of these compounds. The results of the DNA-binding studies revealed that all of the compounds interact with DNA at a minor groove which was further confirmed by molecular docking studies.     

Co<Superscript>II</Superscript> and Rh<Superscript>I</Superscript> complexes with <Emphasis Type="Italic">C</Emphasis><Subscript>2</Subscript>-symmetric chiral diamines of the dioxolane series

The reaction of di-μ-chlorobis(1,5-cyclooctadiene)dirhodium with (4S, 5S)-2,2-dimethyl-4,5-bis(methylaminomethyl)-1,3-dioxolane (1) gave the complex [Rh(cod)(1)]Cl (cod is 1,5-cyclooctadiene). The composition of the complexes CoCl₂ · L₂ and [Rh(cod)(L₂)]X (L₂ = 1, (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane, and (4S, 5S)-2,2-dimethyl-4,5-bis(dimethylaminomethyl)-1,3-dioxolane; X = Cl, TfO) was studied using IR and ¹H NMR spectroscopy. In the Rh^I cyclooctadienediamine complexes, the diene molecule forms a stronger bond with the metal atom than that in the cyclooctadienediphosphine analogs. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2270–2274, October, 2005.     

贫电子环丙烷衍生物与2-巯基苯骈噻唑的反应研究

贫电子环丙烷衍生物1以精制四氢呋喃为溶剂, 与2-巯基苯骈噻唑(2)封管加热反应, 得到产物3和4. 产物3经IR, MS, ¹H NMR, ¹³C NMR和元素分析等数据确定其结构为: (R)-β-取代-(R)-γ-(2-巯基)苯骈噻唑基-γ-对位取代苯基丁酸或(S)-β-取代-(S)-γ-(2-巯基)苯骈噻唑基-γ-对位取代苯基丁酸(3); 产物4通过IR, MS, ¹H NMR, ¹³C NMR, 2D-NOESY谱和元素分析等数据确定其结构为: 反式-β-取代-γ-对位取代苯基-3-丁烯酸(4). 对生成产物的机理也进行了推测.     

Synthesis,characterization and dynamic stereochemistry of thermochromic tris(dithiocarbamato)vanadium(III) complexes stereochemistry of thermochromic tris(dithiocarbamato)vanadium(III) complexes

The vanadium(III) complexes, V(S₂CNMe₂)₃ (1) and V(S₂CN ⁱ Pr₂)₃ (2) were prepared and characterized by analysis, IR, electronic and ¹H NMR spectra. The complexes show reversible thermochromic behaviour. MM2 calculations were used to simulate the molecular structure of 1. For 2, variable temperature ¹H NMR revealed hindered rotation about C–N bonds. The rotational energy barrier (38?kJ?mol^?1) was obtained by molecular mechanics force-field calculations.     

A new benzofuran from Artemisia halodendron Turcz. ex Bess.

A new benzofuran, methyl (2S,2″S,3′E)-[2-(1″-acetoxypropan-2-yl)-2,3-dihydrobenzofuran-5-yl]acrylate (1), and 13 known compounds (2–14) were isolated from an ethanol extract of Artemisia halodendron Turcz. ex Bess. The chemical structures of these compounds were determined by 1D and 2D NMR (¹H-¹H COSY, HMBC, HMQC and NOESY) and HR-ESI-MS spectra, and results were compared with data from the literature. The effects of compounds 1–14 were measured on NF-κB activation, with compounds 2 and 3 exhibiting inhibitory activities against TNF-α-induced NF-κB reporter gene expression in HeLa cells from 10 to 100 μM.     

Palladium(II) complexes with R2edda-derived ligands. Part V. Reaction of O,O′-diethyl-(S,S)-ethylenediamine-N,N′-di-2-(3-methyl)butanoate with K2[PdCl4]

The reaction of K₂[PdCl₄] with [(S,S)-H₂(Et)₂eddv]Cl₂ diester (O,O′-diethyl-(S,S)-ethylenediamine-N,N′-di-2-(3-methyl)butanoate) (1) resulted in [PdCl₂{(S,S)-(Et)eddv-κ² N,N′,κO}] (2) complex with one hydrolyzed ester group. The compound was characterized by spectroscopic methods and it was found that the reaction is diastereoselective (¹H and ¹³C NMR; one diastereoisomer of four possible). In addition, the structure of 2 was confirmed by X-ray diffraction analysis, indicating that the product is the (R,R)–N,N′-configured isomer. DFT calculations support the formation of one diastereoisomer of 2.     

First optically active <Emphasis Type="Italic">PC</Emphasis>-palladacycle bearing a phosphorus atom in an axially chiral environment

Direct aromatic C—H bond activation in the (S _a)-BINOL-derived phosphite (S _a)-HL afforded the dimeric cyclopalladated complex (S _a,S _a)-{Pd(η²-L)(μ-Cl)}₂ (2) which is the first optically active PC-palladacycle bearing a phosphorus atom in an axially chiral environment. ortho-Palladated structure of dimer 2 was confirmed by spectral (¹H and ³¹P NMR) examination of its mononuclear derivatives and by X-ray diffraction analysis of the phosphine adduct (η²-L)PdCl(PPh₃) (4). The enantiomeric purity of the starting ligand remained unchanged in the PC-palladacycle under the thermal conditions used for the cyclopalladation (∼110 °C); this fact was confirmed by the ³¹P NMR spectroscopy after chiral derivatization in situ of dimer (S _a,S _a)-2 with the (R _C )-valinate chiral auxiliary (Val). trans(N,C)-Configuration of the valinate complex (η²-L)Pd(Val) (5) was established by ¹H NMR and supported by DFT calculations. The chirality transfer in the new PC-palladacycle was discussed on the basis of X-ray diffraction data for the phosphine adduct rac-4 and DFT calculations performed for both phosphine and valinate mononuclear derivatives.     

New lipoxygenase and cholinesterase inhibitory sphingolipids from Carthamus oxyacantha

Two new sphingolipids: oxyacanthin A [(2S,3S,4R)-2-{[(2R,5E)-2-hydroxyoctadec-5-enoyl]amino}hexaeicosane-1,3,4-triol; 1] and B [(2S,3S,4R)-2-{[(2R,5E)-2-hydroxyoctadec-5-enoyl]amino}hexaeicosane-1,3,4-triol-1-O-β-D-glucopyranoside; 2], together with 1-octacosanol, β-sitosterol, β-sitosterol 3-O-β-D-glucopyranoside and luteolin 7-O-β-glucopyranoside were isolated from the methanolic extract of the whole plant of Carthamus oxyacantha. Their structures were elucidated using ¹H and ¹³C NMR spectra and 2D NMR analyses (HMQC, HMBC and COSY) in combination with mass spectrometry (EI-MS, HR-EI-MS, FAB-MS and HR-FAB-MS) experiments and in comparison with the literature data of the related compounds. Both the compounds 1 and 2 showed inhibitory potential against lipoxygenase (LOX) in a concentration-dependent manner with IC₅₀ values 83.3 ± 1.3 and 245.7 ± 1.1 µM, whereas compound 2 showed inhibition against enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with IC₅₀ values 65.3 ± 0.1 and 93.6 ± 0.1 µM, respectively.     

Syntheses,spectroscopy, optical properties,and diastereoselectivity of copper(II)-complexes with chiral aminoalcohol based Schiff bases

Chiral aminoalcohol based Schiff bases (R or S)-2-{(E)-(2-hydroxy-1-phenylethylimino)methyl}phenol and (R/S)-2-{(E)-(2-hydroxy-2-phenylethylimino)methyl}phenol coordinate to copper(II)acetate to give enantiopure Λ/Δ- or Δ/Λ-bis[(R or S)-2-{(E)-(2-hydroxy-1-phenylethylimino)methyl}phenoxide-κ²N,O]copper(II), {Λ/Δ-Cu(R-L1)₂ (1) or Δ/Λ-Cu(S-L1)₂ (2)}, and racemic Δ/Λ- and Λ/Δ-bis[(R/S)-2-{(E)-(2-hydroxy-2-phenylethylimino)methyl}phenoxide-κ²N,O]copper(II), {Δ/Λ- and Λ/Δ-Cu(R/S-L2)₂ (3)}, respectively. The complexes are characterized by elemental analyzes, IR, UV–Vis, polarimetry, circular dichroism (CD), differential scanning calorimeter (DSC), and mass spectroscopy. Polarimetry shows the rotation to the left at ?113.6° (1) and to the right at +106.4^o (2). CD spectra show the expected mirror-image relationship with opposite sign of ellipticity maxima (Δε_max = +0.43 for 1 and ?0.42 M^?1 dm³ cm^?1 for 2 at 638 nm) due to the d-d transitions of the metal ion. CD spectral analyzes further reveal a diastereoselectivity or diastereomeric excess towards Λ-Cu(R-L1)₂ or Δ-Cu(S-L1)₂ configuration for 1 or 2 in solution. Similarly, the enantiomeric pair of Δ-Cu(R-L2)₂ and Λ-Cu(S-L2)₂ configurations (CD inactive) for 3 will be preferred in solution. Electronic spectra in different solvents reveal a negative solvatochromism by shifting absorption maxima of the MLCT band to higher energies in solvents of increasing polarity as well as acceptor number. DSC analyzes show an endothermic peak at 525.5 (1) or 528.7 K (2), corresponding to a thermally induced structural phase transformation from distorted square-planar to regular tetrahedral.     

Syntheses,spectroscopy, and catalysis of (η 4-cod)Rh(I)-complexes with (R or S)-2-(salicylaldimine)-2-phenylethanol or (rac)-2-(salicylaldimine)-1-phenylethanol

Condensation of salicyldehyde with (R or S)-2-amino-2-phenylethanol or rac-2-amino-1-phenylethanol gives enantiopure (R or S)-2-(salicylaldimine)-2-phenylethanol (R- or S-H₂L1) or (rac)-2-(salicylaldimine)-1-phenylethanol (rac-H₂L2). The Schiff bases coordinate to [Rh(η ⁴-cod)(μ-O₂CCH₃)]₂ to afford mononuclear [Rh(η ⁴-cod){(R or S)-2-(salicylaldiminato)-2-phenylethanol-κ ² N,O}], [Rh(η ⁴-cod)(R- or S-HL1)] (1 or 2), or [Rh(η ⁴-cod){(rac)-2-(salicylaldiminato)-1-phenylethanol-κ ² N,O}], [Rh(η ⁴-cod)(rac-HL2)] (3). The Schiff base and complexes are characterized by IR-, UV/Vis-, ¹H/¹³C-NMR-, mass-spectroscopy, circular dichroism (CD), and polarimetry. The synthetic and spectroscopic results suggest that deprotonated Schiff base coordinates to [Rh(η ⁴-cod)] as a six-membered N,O-chelate with distorted square planar geometry at rhodium. CD and polarimetry measurements show the enantiopurity of the Schiff bases as well as the complexes in solution. The in situ system composed of [Rh(η ⁴-cod)Cl]₂ and S-H₂L1 has been used as a catalyst for the reduction of acetophenone into rac-1-phenylethanol with 85% conversion in diphenylsilane at 0–5°C.     

Improved synthesis of the enantiomers of propafenone using chiral building blocks

Summary A short and efficient synthesis of the enantiomers of the antiarrhythmic drug propafenone (1) is described using both (R)-isopropylideneglycerol tosylate and (S)-glycidyl tosylate as chiral building blocks. The key step of the high yield synthesis is the acetalization of the carbonyl group in 1-(2-hydroxyphenyl)-3-phenyl-1-propanone (2) which allows application of mild reaction conditions in the subsequent alkylation of the phenolic hydroxy group.With our best wishes dedicated to Prof. Dr.H. Achenbach on the occasion of his 65^th birthday     

Another two novel ceramides from <Emphasis Type="Italic">Zephyranthes candida</Emphasis>

From the the bulbs of Zephyranthes candida (Amaryllidaceae), another two novel ceramides have been isolated and identified. The structures of the two novel compounds were established as (2S,3S,4R,21E,2′R)2-[N-(2′-hydroxynonadecanoyl)-N-(1′′,2′′-dihydroxyethyl)amino]-21-hexacosene-1,3,4-triol, named zephyranamide C (1), and 1,3,4,5,6-pentahydroxy-2-(2′-hydroxyhexacosanoyl-amino)-18-(E)-tetracosene, named zephyranamide D (2). Their structures and stereochemistries were elucidated by spectral techniques including ¹H NMR, ¹³C NMR, as well as HSQC, HMBC, DEPT, and COSY.     

Synthesis,structural characterization,oxygen sensitivity,and antimicrobial activity of ruthenium(II) carbonyl complexes with thiosemicarbazones

[Ru(CO)(PPh₃)₂(η³-O,N³,S-TSC¹)] (1), [Ru(Cl)(CO)(PPh₃)₂(η²-N³,S-TSC²)] (2), and [Ru(Cl)(CO)(PPh₃)₂(η²-N³,S-TSC³)] (3) have been prepared by reacting [Ru(H)(Cl)(CO)(PPh₃)₃] with the respective thiosemicarbazones TSC¹ (2-hydroxy-3-methoxybenzaldehyde thiosemicarbazone), TSC² (3-hydroxybenzaldehyde thiosemicarbazone), and TSC³ (3,4-dihydroxybenzaldehyde thiosemicarbazone) in a 1?:?1 M ratio in toluene and all of the complexes have been characterized by UV–vis, FT-IR, and ¹H and ³¹P NMR spectroscopy. The spectroscopic studies showed that TSC¹ is coordinated to the central metal as a tridendate ligand coordinating via the azomethine nitrogen (C=N), phenolic oxygen, and sulfur to ruthenium in 1, whereas TSC² and TSC³ are coordinated to ruthenium as a bidentate ligand through azomethine nitrogen (C=N) and sulfur in 2 and 3. Oxygen sensitivities of 1–3 and [Ru(Cl)(CO)(PPh₃)₂(η²-N³,S-TSC⁴)] (4), and antimicrobial activities of 1–3 have been determined.     

(S)-(+)-N-取代吡咯烷甲醇衍生物的合成及晶体结构

从L-α-脯氨酸出发,经过酯化、N-烷基化、与格氏试剂反应合成了6个未见文献报道的(S)-(+)-N-取代吡咯烷甲醇衍生物3a～3f,其结构经IR,1HNMR和元素分析测定确证.并用X射线单晶衍射法测定了化合物(S)-(+)-1-[N-(5-氯-2-噻唑甲基)-2-吡咯烷基]-1,1-二苯基甲醇(3e)的晶体结构.晶体为单斜晶系,空间群为P2(1),a=0.8737(14)nm,b=0.9098(14)nm,c=1.2180(17)nm,α=90.00°,β=92.55(3)°,γ=90.00°,V=0.9671(3)nm3,Z=2,Dc=1.3217g/cm3,F(000)=404,R=0.0584,wR=0.1335.     

Synthesis of Chiral 12-Phenyl(2H)dodecanoic Acids: Useful metabolic probes for the biosynthesis of 1-alkenes from fatty acids

The synthesis of chiral 12-phenyi(²H)dodecanoic acids as metabolic probes for the evaluation of the stereo-chemical course of the biosynthesis of 1-alkerses from fatty acids in plants and insects is described. The diastereoisomeric (2R, 3R)- or (2S, 3S)-12-phenyl(2,3?²H₂)dodecanoic acids 11 are obtained in high chemical and optical yield (>97% e.e.) from the readily available (E)-12-phenyl(2,3-²H₂)dodec-2-enoic acid ( 10 ) or (E)-12-phenyldodec-2-enoic acid ( 10a ) by microbial reduction with wet packed cells of Clostridium tyrobutyricum in either ²H₂O or H₂O buffer. (2R)- and (2S)-12-phenyl(2?²H)dodecanoic acids 9 (>97% e.e.) are accessible from the allylic alcohol 6 via Sharpless epoxidation with (+)-L- or (?)-D-diethyl tartrate, Synthetic routes to the (E)- and (Z)-11-phenyl(1?²H) undec-1-enes 16 and 16a as reference compounds are also included.     

Synthesis and Stereochemistry of (1S,3S,4S,7R11R)-3-(4-Nitrophenyl)-11-aza-2,6-dioxatricyclo[5,3,1,04,11]undecane

The reaction of (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediol with glutaraldehyde has been studied. It has been established on the basis of AM1 and PM3 calculations and ¹H NMR spectra recorded in the presence of the shift reagent Eu(fod)₃ that (1S,3S,4S,7R,11R)-3-(4-nitrophenyl)-11-aza-2,6-dioxatricyclo[5,3,1,0^4,11]undecane is formed as the result of the reaction.