Nucleophilic addition of amino acid esters to nitrilium derivatives of closo-decaborate anion

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水相法合成双(环戊二烯基)钛氨基酸配合物的研究

以N-(取代苯基)氨基乙酸及盐与双(环戊二烯基)二氯化钛在水相及有机相反应,得到了五个双(环戊二烯基)钛氨基酸配合物,对配合物进行了熔点、元素分析、IR及^1HNMR的表征,确定了它们的结构。这些配合物在空气中稳定。经比较,水相中的合成反应速度快,操作简便,产物较易分离,产率高。     

Synthesis,characterization and cytotoxicity of platinum(II) complexes containing reduced amino acid ester Schiff bases

Nine platinum(II) complexes containing reduced amino acid ester Schiff bases were synthesized and characterized using spectroscopy (¹H NMR, ¹³C NMR, infrared), elemental analysis and molar conductivity. The interaction of these complexes with salmon sperm DNA was investigated by means of ultraviolet and circular dichroism spectroscopies. The potential antitumor activity of all compounds was tested in vitro on HeLa and A549 tumor cell lines. Almost all the complexes exhibited better cytotoxic activity than cisplatin against these cell lines.     

手性酒石酸二酰胺配体的合成及其锡络合物与苯甲醛的不对称加成

通过酒石酸乙酯和不同胺的酰胺化, 相应地合成到(+)N,N'-二苯基酒石酸二酰胺(2), (+)N,N'-二苄基酒石酸二酰胺(3),(+)N,N'-二环己基酒石酸二酰胺(4)和(+)N,N'-二正辛基酒石酸二酰胺(5).氯化亚锡与2当量的酒石酸二酰胺反应, 再加入烯丙基溴可制得手性锡络合物6, 锡络合物与苯甲醛反应,得到光学活性的高烯丙基化合物, 产率42～64％ , e.e.值24～62％.     

1,3-dipolar cycloaddition of nitrones to free and coordinated nitriles: Routes to control the synthesis of 2,3-dihydro-1,2,4-oxadiazoles

Data on 1,3-dipolar cycloaddition of nitrones to free and coordinated nitriles producing 2,3-dihydro-1,2,4-oxadiazoles (or Δ⁴-1,2,4-oxadiazolines) are summarized. The latter compounds belong to the virtually unknown class of heterocyclic systems. The main factors responsible for the cycloaddition reactions are discussed. Particular attention is given to the role of metal centers in controlling the synthesis of 2,3-dihydro-1,2,4-oxadiazoles. Dedicated to Academician O. M. Nefedov on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1803–1815, November, 2006.     

Remarkable reactions of cyclooctatetraene diiron-bridging carbyne complexes with amino and amido compounds: nucleophilic addition to and breaking of the cyclooctatetraene ring

The reactions of the cationic, diiron-bridging carbyne complexes [Fe(2)(mu-CAr)(CO)(4)(eta(8)-C(8)H(8))]BF(4) (1, Ar=C(6)H(5); 2, Ar=p-CH(3)C(6)H(4); 3, Ar=p-CF(3)C(6)H(4)) with LiN(C(6)H(5))(2) in THF at low temperature gave novel N-nucleophilic-addition products, namely, the neutral, diiron-bridging carbyne complexes [Fe(2)(mu-CAr)(CO)(4)(eta(7)-C(8)H(8)N(C(6)H(5))(2))] (4, Ar=C(6)H(5); 5, Ar=p-CH(3)C(6)H(4); 6, Ar=p-CF(3)C(6)H(4))). Cationic bridging carbyne complexes 1-3 react with (C(2)H(5))(2)NH, (iC(3)H(7))(2)NH, and (C(6)H(11))(2)NH under the same conditions with ring cleavage of the COT ligand to produce the novel diiron-bridging carbene inner salts [Fe(2)[mu-C(Ar)C(8)H(8)NR(2)](CO)(4)] (7, Ar=C(6)H(5), R=C(2)H(5); 8, Ar=p-CH(3)C(6)H(4), R=C(2)H(5); 9, Ar=p-CF(3)C(6)H(4), R=C(2)H(5); 10, Ar=C(6)H(5), R=iC(3)H(7); 11, Ar=p-CH(3)C(6)H(4), R=iC(3)H(7); 12, Ar=p-CF(3)C(6)H(4), R=iC(3)H(7); 13, Ar=C(6)H(5), R=C(6)H(11); 14, Ar=p-CH(3)C(6)H(4), R=C(6)H(11), 15, Ar=p-CF(3)C(6)H(4), R=C(6)H(11)). Piperidine reacts similarly with cationic carbyne complex 3 to afford the corresponding bridging carbene inner salt [Fe(2)[mu-C(Ar)C(8)H(8)N(CH(2))(5)](CO)(4)] (16). Compound 9 was transformed into a new diiron-bridging carbene inner salt 17, the trans isomer of 9, by heating in benzene. Unexpectedly, the reaction of C(6)H(5)NH(2) with 2 gave a novel COT iron-carbene complex [Fe(2)[=C(C(6)H(4)CH(3)-p)NHC(6)H(5)](mu-CO)(CO)(3)(eta(8)-C(8)H(8))] (18). However, the analogous reactions of 2-naphthylamine with 2 and of p-CF(3)C(6)H(4)NH(2) with 3 produce novel chelated iron-carbene complexes [Fe(2)[=C(C(6)H(4)CH(3)-p)NC(10)H(7)](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (19) and [Fe(2)[=C(C(6)H(4)CF(3)-p)NC(6)H(4)CF(3)-p](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (20), respectively. Compound 18 can also be transformed into the analogous chelated iron-carbene complex [Fe(2)[=C(C(6)H(4)CH(3)-p)NC(6)H(5)](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (21). The structures of complexes 6, 9, 15, 17, 18, and 21 have been established by X-ray diffraction studies.     

Reactivity of diacetylplatinum(II) complexes: Oxidative addition of halogens and hydrogen halides

Diacetylplatinum(II) complexes [Pt(COMe)₂()] ( = bpy, 3a; 4,4′-t-Bu₂-bpy, 3b), obtained by the reaction of [Pt(COMe)₂X(H)()] with NaOH in CH₂Cl₂/H₂O, were found to undergo oxidative addition reactions with halogens (Br₂, I₂) yielding the platinum(IV) complexes (trans, OC-6-13)/(cis, OC-6-32) [Pt(COMe)₂X₂()] ( = bpy, X = Br, 4a/4b; I, 4c/4d;  = 4,4′-t-Bu₂-bpy, X = Br, 4e/4f; I, 4g/4h). The diastereoselectivity of the reactions proved to be strongly dependent on the solvent. The oxidative addition of (SCN)₂ resulted in the formation of (OC-6-13)-[Pt(COMe)₂(SCN)₂()] ( = bpy, 4i; 4,4′-t-Bu₂-bpy, 4j). In a reaction the reverse of their formation, the diacetylplatinum(II) complexes 3 underwent oxidative addition with anhydrous HX (X = Cl, Br, I), prepared in situ from Me₃SiX/H₂O, yielding diacetyl(hydrido)platinum(IV) complexes [Pt(COMe)₂X(H)()] ( = bpy, X = Cl, 5a; Br, 5b; I, 5c;  = 4,4′-t-Bu₂-bpy, X = Cl, 5d; Br, 5e; I, 5f). Furthermore, diacetyldihaloplatinum complexes 4 were found to undergo reductive elimination reactions in boiling methanol yielding acetylplatinum(II) complexes [Pt(COMe)X()] ( = bpy, X = Br, 6b; I, 6c;  = 4,4′-t-Bu₂-bpy, X = Br, 6e; I, 6f). All complexes were characterized by microanalysis, IR and ¹H and ¹³C NMR spectroscopy. Additionally, the bis(thiocyanato) complex 4j was characterized by single-crystal X-ray diffraction analysis.     

Nucleophilic addition of bifunctional sulfimidosulfides to platinum(<Emphasis Type="SmallCaps">IV</Emphasis>)-coordinated nitriles

Reactions of the platinum(IV) nitrile complexes [PtCl₄(RCN)₂] (R = Me, CH₂Ph, Ph) with 1,2- and 1,4-PhS(=NH)C₆H₄SPh in CH₂Cl₂ afforded addition products of sulfimides and coordinated nitriles, viz., the [PtCl₄{NH=C(R)N=S(Ph)(C₆H₄SPh)}₂] complexes. The latter were isolated in 75—90% yields and characterized by elemental analysis, positive-ion FAB mass spectrometry, IR spectroscopy, and ¹H and ¹³C¹H NMR spectroscopy. The temperature dependence of the ¹H NMR spectra of the model [PtCl₄{NH=C(R)N=SPh₂}₂] complexes (R = Me, Et) in CD₂Cl₂ studied in a temperature range from +40 to -70 °C demonstrated that E—Z isomerization of the ligands is a dynamic process in a range from +40 to -10 °C. The activation free energy of this process was calculated.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1618–1622, August, 2004.     

Structural study of bis(triorganotin(IV)) esters of 4-ketopimelic acid

The set of six bis(triorganotin(IV)) esters of 4-ketopimelic acid was prepared. Their structures were studied using IR, NMR and X-ray crystallographic (cyclohexyl and ethyl derivatives) techniques both in solution and the solid state. Five of these compounds are polymeric in the solid state and depolymerise upon dissolving in non-coordinating and/or addition of coordinating solvent to monomeric species with four-coordinated tin atom or complexes with donor solvent with five-coordinated tin central atom. The tricyclohexyltin derivative is dimeric in the solid state and monomeric in solution.     

Asymmetric dearomatization of the furan ring promoted by conjugate organolithium addition to (menthyloxy)(3-furyl)carbene complexes of chromium

The sequential low-temperature addition reaction of an organolithium compound and methyl triflate to (menthyloxy)(3-furyl)carbene complexes of chromium and tungsten proceeded with excellent regioselectivity (1,4-addition) and diastereoselectivity (2,3-trans disposition of the nucleophile and electrophile groups) to afford new 2,3-disubstituted (2,3-dihydro-3-furyl)carbene complexes. In addition, a high degree of diastereofacial selectivity was achieved by employing alkenyllithium compounds. After detachment of both the metal fragment and the chiral auxiliary group, trisubstituted 2,3-dihydrofuran derivatives containing a quaternary stereogenic center at the C3 position were obtained. The characterization, including X-ray crystallography, of a novel type of stable four-membered chelate (eta(2)-alkene)tetracarbonylcarbene complex of chromium is also reported.     

Mechanistic study of asymmetric Michael addition of malonates to enones catalyzed by a primary amino acid lithium salt

A mechanistic study was carried out for the asymmetric Michael addition reaction of malonates to enones catalyzed by a primary amino acid lithium salt to elucidate the origin of the asymmetric induction. A primary β-amino acid salt catalyst, O-TBDPS β-homoserine lithium salt, exhibited much higher enantioselectivity than that achieved with the corresponding catalysts derived from α- and γ-amino acids for this reaction. Detailed studies of the transition states with DFT calculations revealed that the lithium cation and carboxylate group of the β-amino acid salt catalyst have important roles in achieving high enantioselectivity in the Michael addition reaction of malonates to enones.     

Synthesis of Boronated Amidines by Addition of Amines to Nitrilium Derivative of Cobalt Bis(Dicarbollide)

A series of novel cobalt bis(dicarbollide) based amidines were synthesized by the nucleophilic addition of primary and secondary amines to highly activated B-N⁺≡C–R triple bond of the propionitrilium derivative [8-EtC≡N-3,3′-Co(1,2-C₂B₉H₁₀)(1′,2′-C₂B₉H₁₁)]. The reactions with primary amines result in the formation of mixtures of E and Z isomers of amidines, whereas the reactions with secondary amines lead selectively to the E-isomers. The crystal molecular structures of E-[8-EtC(NMe₂)=HN-3,3′-Co(1,2-C₂B₉H₁₀)(1′,2′-C₂B₉H₁₁)], E-[8-EtC(NEt₂)=HN-3,3′-Co(1,2- C₂B₉H₁₀)(1′,2′-C₂B₉H₁₁)] and E-[8-EtC(NC₅H₁₀)=HN-3,3′-Co(1,2-C₂B₉H₁₀)(1′,2′-C₂B₉H₁₁)] were determined by single crystal X-ray diffraction.     

Synthesis,characterization, and biological activity of new mixed ammine/amine platinum(IV) complexes

A series of mixed ammine/amine platinum(IV) complexes with lipophilic ligands in their axial positions were designed, synthesized, and spectrally characterized. In vitro cytotoxicity evaluation of these complexes and their lead compounds have been carried out against A549, SMMC-7721, MCF-7, and SW480 human cancer cell lines. The introduction of carboxylate ions as leaving group can improve the aqueous solubility and stability of the platinum(II) complexes. The carboxylato ligands and chloride ligands in the axial position markedly increased the lipophilicity and cytotoxicity of compounds C4 and C5. Particularly, compound C5 showed two to eight times higher cytotoxicity than cisplatin and satraplatin against selected cell lines. For its oral activity and no cross-resistance potentiality, C5 is expected to be an antitumor platinum drug candidate. This novel class of platinum compounds represents a valuable lead in the development of new-generation agents capable of demonstrating cytotoxicity superior to that of the clinically established cisplatin.     

Design of enzyme reactors as chromatographic columns for racemic resolution of amino acid esters

Summary Racemic resolution of aromatic and aliphatic amino acid esters into L-amino acid and D-amino acid ester via LC and HPLC is achieved by using enzyme reactors as chromatographic columns. For this purpose α-chymotrypsin and trypsin are immobilized on Eupergit C, Sepharose 4B and Lichrosorb-Diol.     

Synthesis and properties of amino acid esters of hydroxypropyl cellulose

The amino acid esters of hydroxypropyl cellulose (HPC) [R′ = H ( 2a ), CH₃ ( 2b ), CH₂CH(CH₃)₂ ( 2c ), CH₂CONH₂ ( 2d ), CH₂CH₂CONH₂ ( 2e ), CH₂CH₂CH₂CH₂ NHOCOC(CH₃)₃ ( 2f )] were synthesized in good yield by the reaction of t‐butoxycarbonyl (t‐Boc)‐protected amino acids with hydroxy groups of HPC ( 1 ; molar substitution (MS), 4.61). The amino acid functionalities displaying varied chemical nature, shape, and bulk were utilized and the bulk of the substituent on the α‐carbon of amino acids was elucidated to be of vital significance for the observed degree of incorporation (DS_Est). The ¹H NMR spectra and elemental analysis were employed to determine the degree of incorporation of amino acid moiety (DS_Est) and almost complete substitution of the hydroxy protons was revealed for 2a , 2b , and 2f . The presence of the peaks characteristic of the carbonyl group in the FTIR spectra furnished further evidence for the successful esterification of HPC. The starting as well as the resulting polymers ( 1 and 2a – f ) were soluble in polar organic solvents; however, the esterification of 1 with bulky organic moieties resulted in an increased hydrophobicity as all of the amino acid‐functionalized polymers ( 2a – f ) were insoluble in water. The onset temperatures of weight loss of 2a – f were 175–230 °C, indicating fair thermal stability. The amino acid functionalization led to the enhanced polymer chain stiffness, and the glass transition temperatures of the derivatized polymers were 30–40 °C higher than that of 1 (T_g 3.9 °C; cf. T_g of 2a – f , 35.1–43.3 °C). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2326–2334, 2008     

Synthesis and physicochemical studies on Co(III) complexes

Complexes of Co(III) with 2-hydroxyacetophenone-thiosemicarbazone, 2-hydroxy-3-methylacetophenonethiosemicarbazone and 2-hydroxy-4-methyl-acetophenonethiosemicarbazone, and the addition complexes of 2-hydroxy-acetophenone thiosemicarbazone with ammonia, pyridine, aniline,o-toluidine,m-toluidine andp-toluidine have been synthesized and characterized on the basis of their conductivities, electronic and infrared spectral data. All complexes are low-spin octahedral in nature. Various parameters have been obtained using ligand field theory.     

Synthesis and coordination chemistry of organotin(IV) complexes of 2,3-methylenedioxyphenylpropenoic acid

The synthesis, spectroscopy, and antitumor behavior of organotin(IV) complexes of 2,3-methylenedioxyphenylpropenoic acid are described. The spectroscopic data indicate 1 : 2 and 1 : 1 metal to ligand stoichiometry in case of di- and trioganotin(IV) compounds and hypervalency of Sn(IV) in trigonal bipyramidal and octahedral modes. Mass spectrometric and elemental analysis data support the solid and solution spectroscopic results. The complexes have been evaluated in vitro against crown gall tumor and bio-activity screenings showed in vitro biological potential. The nature of covalent attachments (methyl, ethyl, n-butyl, phenyl, and n-octyl) of Sn(IV) played a decisive role for bioactivity. All the compounds have been studied in solution by NMR (¹H, ¹³C) and also in solid state using FTIR, mass spectrometry, and by X-ray crystallography. The molecular structure of Et₂Sn(IV) and Me₃Sn(IV) derivatives confirm the behavior of di- and tri-organotin(IV) compounds in solid state. Mono-organotin derivatives are octahedral both in solid and solution.     

Dioxobridged complexes of molybdenum (IV) and tungsten (IV) with N-alkylphenothiazines and their interactions with L-cysteine and L-histidine

Six new dioxobridged complexes of molybdenum (IV) and tungsten (IV) with N-alkylphenothiazines having the general formula M₂O₄(L)₂(H₂O)₂ [where M = molybdenum or tungsten and L = N-alkylphenothiazines] have been synthesised. The complexes have been characterised on the basis of analytical, molar conductance, magnetic susceptibility, spectral data, TGA and DTA. The low magnetic moments for the complexes are due to spin-spin interaction or metal-metal bonding. The interactions of these complexes with some biologically important amino acids have been studied.     

The effect of hydrophobic-lipophilic interactions on chemical reactivity. 10. The competition between the aggregation of long-chain esters and the formation of inclusion complexes of these esters with amylose

The hydrolytic pseudo-first-order rate constants (k _ad) ofp-nitrophenyl esters of dodecanoic acid (C12) and hexadecanoic acid (C16) at different initial substrate concentrations ([S] _i ) in the six aquiorgano binary mixtures of different compositions (ϕ) were measured. These rate constants (k _ad) were compared with the corresponding rate constants obtained in the absence of sodium carboxymethylamylose (Na-CMA) (k _un) in order to study the competition between the formation of inclusion complexes of these esters with Na-CMA and the aggregation of these long-chain substrates. Values of ΔCAgC andk _ad/k _un were compiled and their significance discussed on the basis of a postulated two-path mechanism. Our results suggest that in addition to path A which involves encapsulation by Na-CMA of the monomeric C12 or C16 only, there is a second path (path B). Path B describes a process in which Na-CMA breaks up aggregates of all sizes into smaller ones as well as monomeric species which can be wrapped-up by Na-CMA simultaneously or subsequently.