Synthesis of (−)-(1′S,4aS,8aR)- and (+)-(1′S,4aR,8aS)-4a-ethyl-1-(1′-phenylethyl)-octahydroquinolin-7-ones

A synthesis of the enamine (−)-(1′S)-5-ethyl-1-(1′-phenylethyl)-1,2,3,4-tetrahydropyridine 4 and its application in a synthesis of (−)-(1′S,4aS,8aR)- and (+)-(1′S,4aR,8aS)-4a-ethyl-1-(1′-phenylethyl)-octahydroquinolin-7-ones 5 and 6 is described. In addition, an X-ray study of 6 is reported. Finally, the preparation of (+)-(4aS,8aR)-4a-ethyl-octahydroquinolin-7-one 7 is described.     

Synthesis and cytotoxicity of dinuclear platinum(Ⅱ) complexes of (1S, 3S)-1, 2, 3, 4-tetrahydroisoquinolines

A series of novel dinuclear platinum(Ⅱ) complexes with (1S, 3S)-1,2,3,4-tetrahydroisoquinolines as the ligands were synthesized as potential anticancer agents in several steps starting from commercially available L-DOPA. The cytotoxicities of the series of dinuclear platinum(Ⅱ) complexes of tetrahydroisoquinoline were tested against HCT-8, BEL-7402, A2780, MCF-7, Hela, A549 and BGC-823 cell lines by the MTT test. These complexes showed selective inhibition activity against cisplatin-insensitive cell line Skov3.     

Synthesis,Structure and Biological Activities of 2-(1H- 1,2,3-Benzotriazol-1-yl)-1-(4-methylphenyl)-2- (1H-1,2,4-triazol-1-yl)-1-ethanone

IntroductionTriazole derivatives have become the most rapidlyexpanding group of antifungal compounds with advanta-ges of lowtoxicity, high oral bioavailability and broad-spectrum antifungal activity, which can be used againstfungi including most yeasts an…     

Synthesis, Structure and Dielectric Property of Ba_(1- x)Sr_xZr_yTi_(1- y)O_3

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Synthesis,characterization, and biological evaluation of silver(I) complexes of N′-(1-(pyrazin-2-yl)ethylidene)picolinohydrazide

Three Ag⁺ complexes, [Ag(L)(NO₃)]_n (1), {[Ag(L)]·SbF₆·CH₂Cl₂}_n (2), and {[Ag(L)]·SO₃CF₃·CHCl₃}_n (3), based on a hydrazone ligand L have been obtained (L = N′-(1-(pyrazin-2-yl)ethylidene)picolinohydrazide) and characterized. Complexes 1–3 all show 1-D chain-like structures. Their antibacterial activity and interaction with serum albumin were investigated. These results indicate that these complexes show good antibacterial activities and binding affinity to serum albumin.     

Unexpected retro-Michael reaction of (−)-(1′S,4aS,8aR)- and (+)-(1′S,4aR,8aS)-4a-ethyl-1-(1-phenylethyl)octahydroquinolin-7-ones

An unexpected retro-Michael reaction of (−)-(1′S,4aS,8aR)-and (+)-(1′S,4aR,8aS)-4a-ethyl-1-(1′-phenylethyl)octahydroquinolin-7-ones 1 and 2 is described. In addition, a diastereospecific intramolecular Michael reaction of 3·HCl and 4·HCl is reported.     

Silicon-induced diastereoselectivity of the catalyzed phosphorylation of 1-(perfluoroalkyl)-ω (trialkylsilyl)alkan-1-ols

The stereochemistry of catalytic phosphorylation of 1-(perfluoroalkyl)--(trialkylsilyl)alkan-1-ols with pentavalent phosphorus acid monochlorides (phosphonochloridates, methyl(phenyl)phosphinic chloride, and phosphorochloridates) was studied. The effects of the structures of alcohols and phosphorylating agents on the degree of the reaction diastereoselectivity were investigated. Methylphosphonochloridates were found to react most stereoselectively; the diastereoselectivity of the phosphorylation is independent of the donor or acceptor character of substituents at the phosphorus atom, being determined by their volumes. In the series of silylalkanols, the diastereoselectivity of the reaction the higher the closer the Si atom to the reactive site of the molecule, the larger the volume of the perfluoroalkyl substituent, and the more pronounced the electron-withdrawing properties of the substituents at the Si atom. A reaction mechanism is proposed that rationalizes the stereoselectivity of the reaction.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1930–1936, September, 2004.     

Structural and bonding investigation of an unbridged donor-acceptor complex 1-(2,2′-bipyrimidine)-1-(t-butyl)-2, 3-bis(trimethylsilyl) -2,3-dicarba-1-galla-closo-heptaborane(6)

The reaction between thecloso-gallacarborane, 1-(t-C₄H₉)-1-Ga-2,3-(SiMe₃)₂-2,3-C₂B₄H₄ (1), and 2,2-bipyrimidine in a molar ratio of 11 in dry benzene produced the unbridged donor-acceptor complex 1-(2,2-C₈H₆N₄)-1-(t-C₄H₉)-1-Ga-2,3-(SiMe₃)₂-2, 3-C₂B₄H₄ (2) as a pale-yellow crystalline solid in 81% yield. The spectroscopic data of2 are almost identical to those of the bridged species 1,1-(2,2-C₈ H₆N₄)-[1-(t-C₄H₉)-1-Ga-2,3-(SiMe₃)₂-2,3-C₂ B₄H₄]₂ (3). However, the single-crystal X-ray structure of2 reveals that the complex consists of only one distorted gallacarborane unit and a bipyrimidine molecule, that acts as a bidentate ligand. The apical gallium in2 is displaced further away from the centroidal position above the carborane than it is in 1. Despite the steric hindrance imposed by the bulky trimethylsilyl groups on the cage carbons, the Ga-C_(t-buty) bond is tilted toward the cage carbon atoms. Complex2 crystallizes in the monoclinic space groupP2₁ witha=11.279 (3),b=10.060 (3),c=11.911 (3) Å,=94.94 (2)°,V=1346.5 (6) ų,Z=2,D _x=1.24g cm^–3, (MoK) F(000)= 528, andT=220 K. Full-matrix least-squares refinement for2 converged at R=0.036 andRw= 0.045 for 3032 observed reflections. Molecular orbital calculations showed that antibonding interactions between the gallium and carborane cage carbons, induced by base complexation, are a contributing factor to the gallium's slip distortion that is found in2.     

Evaluation of Transient Absorption Spectra of N, N, N, N- Tetra - ( p -methylphenyl ) - 4, 4- diamino - 1, 1- diphenyl Ether ( TPDAE ) for Electron Transfer from TPDAE to Fullerenes ( C_(60) / C_(70) ) by Laser Flash Photolysis

Fullerenes C60 and C70 have high electron affinity ( 2.6 - 2.8 ev ) and readily form anions on electronchemical reduction1, which were famous as electron acceptor in photo-excitation because of symmetrical shape, large size, and properties of its p - electron system2. After observation of molecular ferromagnetism3 in the tetrakis (dimethylamino ) ethylene salt of C60 as well as the occurrence of ultra-fast photoinduced electron transfer within the dimethyl aniline - C60 complex4, prompted us…     

Synthesis of propyl O-(α-L-rhamnopyranosyl)-(1→3)-[2,4-di-O-(2s-methylbutyryl)-α-L-rhamno-pyranosyl]-(1→2)-(3-O-acetyl-β-D-glucopyranosyl)-(1→2)-β-D-fucopyranoside,the tetrasaccharide moiety of Tricolorin A

Propyl O-(α-L-rhamncpyranosyl)-(1→3)-[2,4-di-O-(2s-methylbutyryl)-α-L-rham-nopyranosyl]-(1→2)-(3-O-acetyl-β-D-glucopyranosyl)-(1→2)-β-D-fucopyranoside (1), the tetrasac-charide moiety of Tricolorin A, was synthesized in total 23 steps with a longest linear sequence of 10 steps, and overall yield of 3.7% from D-Glucose. The isomerization of the dioxolane-type berzyli-dene in the presence of NIS/AgOTf was observed. Tetrasaccharide 1 exhibited no activity against the cultured P388 cell as Tricolorin A did.     

Asymmetric synthesis of (−)-(1R,7aS)-absouline

The most efficient and concise asymmetric synthesis of (?)-(1R,7aS)-absouline to date, which was accomplished in eight steps and 20% overall yield from commercially available starting materials, is described. The doubly diastereoselective conjugate addition of lithium (S)-N-benzyl-N-(α-methylbenzyl)-amide to an enantiopure α,β-unsaturated ester derived from l-proline was employed as the key step. Subsequent hydrogenolytic N-debenzylation and acid-promoted cyclisation of the resultant β-amino ester produced the 1-aminopyrrolizidin-3-one scaffold, then reduction with DIBAL-H was followed by DCC-mediated coupling with (E)-p-methoxycinnamic acid to complete the synthesis of (?)-(1R,7aS)-absouline.     

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.     

Synthesis of 1-(3-(1,2,4-triazol-1-yl)-2,3,6-trideoxy-L-arabino-hexofuranosyl)uracils via an α,β-unsaturated aldehydrohexose

Summary Mercuric catalyzed hydrolysis of acetylatedL-rhamnal1 gave the ,-unsaturated aldehyde2. 1,2,4-Triazole was coupled, in a Michael type addition reaction, to2 at C-3 in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to give, after acetylation at the anomeric center, an anomeric mixture of 1,5-di-O-acetyl-3-(1,2,4-triazol-1-yl)-2,3,6-trideoxy-L-arabino-hexofuranose (3). Reaction of3 with silylated 2,4-dihydroxypyrimidines4 in the presence of trimethylsilyl triflate as catalyst followed by deprotection with 33% methylamine in absolute ethanol afforded the corresponding nucleosides7 and8.

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Synthese von 1-(3-(1,2,4-Triazol-1-yl)-2,3,6-trideoxy-L-arabino-hexofuranosyl)uracilen über eine ,-ungesättigte Aldohexose

Zusammenfassung Die quecksilberkatalysierte Hydrolyse von acetyliertemL-Rhamnal1 ergab die ,-ungesättigten Aldehyde2. 1,2,3-Triazol wurde in Gegenwart von 1,8-Diazabicyclo[5.4.0]-7-undecen mittels einer Addition vom Michael-Typ an C-3 von2 gekoppelt und ergab dann nach Acetylierung am anomeren Zentrum eine anomere Mischung von 1,5-Di-O-acetyl-3-(1,2,4-triazol-1-yl)-2,3,6-trideoxy-L-arabino-hexofuranose (3). Die Reaktion von3 mit silyliertem 2,4-Di-hydroxypyrimidinen4 in Gegenwart von Trimethylsilyltriflat in absolutem Ethanol ergab die entsprechenden Nucleoside7 und8.

     

Enzymatic resolution of (±)-1-ferrocenylethylamine

(±)-1-Ferrocenylethylamine was resolved by a highly enantioselective acetylation catalyzed by Candida antarctica B lipase.     

Asymmetric Conjugate Addition of Alcohols to (R)-(-)-5-[(1R,2S,5R)-Menthyloxy]-2-(5H)-Furanone

(R)-(-y5-[(IR,2S,5R)-menthyloxy](1)isausefulchiralsynthonreadilypreparedonatWo-stepprocedure-l']FindingsoffuranoneringsexistingascomponentSofsomenaturalproductSI'laswellastheiractivereactivityl']havestimu1atedeXtensiveresearchofitSasymmetricreactionswhichincludeDiels-Alderreactions,l']l,3-dipo1arcycloadditions,['1Michaelauditionsl5]andconjugateedditionsofaminesl']andmercaPtans.g4:,::7f:7':theseadductsledtovariousmultifunctionalhomochiralbuildingblockssuchas2-alkyl-l,4-butanediols,I'l2-aI…     

Mass-spectral Study of 9-[α(β,γ)-Picolylidene]-1(4)-azafluorenes

A mass-spectral study was carried out on the behavior of the Z- and E-isomers of 9-picolylideneazafluorenes. A possible mechanism for the elimination of a hydrogen atom from the M⁺ ion of the Z- and E-isomers of 1(4)-azafluorene derivatives was examined. Mass spectrometry permitted a distinction between compounds isomeric relative to the position of the nitrogen atom in the azafluorene fragments and also the Z- and E-isomers of picolylidene derivatives of 1- and 4-azafluorenes possessing - and -pyridyl substituents.     

Synthesis,halogenation and structural characterization of (Z)-1-[2-(triphenylstannyl)vinyl]-l-cyclododecanol

Synthesis and characterization of (Z)-1-[2-(triphenylstannyl)vinylj-l-cyclododecanol,c-(CH2)11C(OH)CH=CHSnPh3,are reported,together with its halogenation by I2,Br2 and IC1 to yield derivatives of the types c-(CH2)11C(OH)CH=CHSnPh3_nXn (n=1,2; X=I,Br,Cl,respectively).The molecular structures of two compounds have been determined by X-ray diffraction analysis.The tin atom exhibits a distorted tetrahedral geometry in the crystal of (Z)-1-[2-(triphenylstannyl)vinyl]-1-cyclododecanol,but a trigonal bipyramidal geometry in the monoiodo-derivative (Z)-1-[2-(diphenyliodo-stannyl)vinyl]-l-cyclododecanol and other derivatives,in which significant intramolecular coordinative interaction HO→Sn is observed.And the formation of a five-membered tin containing ring is significant for their antitumour activities.     

Electrochemical and electrocatalytic studies of the N,N′-(1R,2R)-(–)-1,2-cyclohexylenebis(salicylideneiminato)cobalt(II) complex

The electrochemical properties and catalytic activity of a Co(II) complex with the optically active Schiff base derived from (1R,2R)-(–)-cyclohexanediamine and salicylaldehyde have been studied in non-aqueous solutions. When dissolved in deoxygenated non-aqueous solutions, the complex exhibits reversible redox properties for the Co(II)/Co(III) couple. Electrochemical reduction of oxygen and oxidation of cobalt(II) was observed on cyclic voltammograms of solutions containing both dioxygen and the Schiff base-cobalt(II) complex. An anodically formed film on a platinum electrode, studied by means of X-ray photoelectron spectroscopy, revealed the presence of the oxidized Co(III) species. Cyclic voltammetry of oxygenated solutions examined after a period of time indicates an electrochemical activity of coordinated superoxo/peroxo species in the 0.7–1.1 V potential range. In the presence of 4-methyl-1-cyclohexene the cyclic voltammetry curves reveal changes similar to those caused by the removal of oxygen. The GC-MS technique was used to identify some of the products formed by the catalytic oxidation of cyclohexene and 4-methyl-1-cyclohexene. Electronic Publication     

Syntheses,Structure and Biological Activities of 2-(1H-Benzo [1,2,3]triazole-1-yl)-1-(3-methyl-4-bromobiphenyl)-2-(1H-1,2,4-triazole-1-yl)ethanone

Introduction1,2,4-Triazole derivatives represent an interesting class of heterocyclic compounds[1]and have become the most rapidly expanding group of antifungal compounds with the advantages of toxicity, high oral bioavailabi-lity, and broad spectrum of a…