Synthesis and antiviral bioactivity of novel chalcone derivatives containing purine moiety

A series of novel chalcone derivatives containing purine group was synthesized and evaluated for their antiviral activities against cucumber mosaic virus and tobacco mosaic virus. Compound 3o exhibited remarkable antiviral activities and strong combining capacity to tobacco mosaic virus coat protein.     

Synthesis and biological evaluation of novel 1,2,4-triazole containing 1,2,3-thiadiazole derivatives

A series of novel 1,2,4-triazoles containing 1,2,3-thiadiazole derivatives were designed and synthesized. Their structures were confirmed by melting points, IR, 1H NMR, and elemental analysis and ESI-MS or HRMS. Preliminary bioassays indicated that these compounds exhibited very good insecticidal activity against Aphis laburni at 100 μg/mL, with mortality no less than 95%. Compounds 6a, 6c, 6f, 61 showed higher curative activity against TMV and compound 6h showed a higher induction effects against TMV in vivo at 100 μg/mL. Collectively, our data demonstrate a new strategy for control of insects and viruses.     

Asymmetric hydrogenation reactions with Rh and Ru complexes bearing phosphine–phosphites with an oxymethylene backbone

Phosphine–phosphites 3a and 3b, derived from diphenylhydroxymethyl phosphine have been prepared. From these ligands [Rh(COD)(3a)]BF₄ 5a and RuCl₂(3b)[(S,S)-DPEN] 6b (DPEN = 1,2-diphenylethylenediamine) were synthesized and their structure determined by X-ray diffraction. Ligands 3 are characterized by a small bite angle of 83°. In addition, 5a led to an active catalyst for the hydrogenation of olefins, giving enantioselectivities of up to 96% ee. Likewise, compound 6b showed good activity and enantioselectivity in the hydrogenation of N-1-phenyl ethylidene aniline and a completed reaction at S/C = 500 in 24 h with 83% ee.     

Lewis acid-assisted olefin cross-metathesis reaction: an efficient approach for the synthesis of glycosidic-pyrroloquinolinone based novel building blocks of camptothecin and evaluation of their antitumor activity

A series of glycosidic-pyrroloquinolinone based novel building blocks of camptothecin (2a–g) were synthesized via Lewis acid-assisted olefin cross-metathesis reaction using Ti(OⁱPr)₄ 30 mol % and 10 mol % of Grubb’s second generation catalyst with good to excellent yields. Most of these compounds exhibited significant growth inhibitory effects on all the tested cancer cell lines and three compounds (2c, 2d and 2e) showed potent cytotoxic activity.     

Synthesis,antiviral activity,and 3D-QSAR study of novel chalcone derivatives containing malonate and pyridine moieties

Several novel chalcone derivatives containing malonate and pyridine moieties were synthesized, and their structures were confirmed by ¹H nuclear magnetic resonance, ¹³C nuclear magnetic resonance, ¹⁹F nuclear magnetic resonance, infrared, and elemental analyses. Antiviral bioassays revealed that most of the compounds exhibited good antiviral activity against cucumber mosaic virus (CMV) at 500 μg/mL. In particular, compounds 5l and 5n showed significant curative activities against CMV in vivo with 50% effective concentration (EC₅₀) values of 186.2 and 211.5 μg/mL, respectively; these values are even better than that of ningnanmycin (330.5 μg/mL). A 3D quantitative structure–activity relationship study was carried out using the comparative molecular field analysis technique based on curative activities against CMV. Results revealed good predictive ability with cross-validated q² and non-cross-validated r² values of 0.517 and 0.990, respectively.     

Intramolecularly donor-stabilized silenes: Part 6. The synthesis of 1-[2,6-bis(dimethylaminomethyl)phenyl]silenes and their reaction with aromatic aldehydes

The intramolecularly donor-stabilized silenes ArR¹SiC(SiMe₃)₂ (3a–d) (3a: R¹ = Me; 3b: R¹ = t-Bu; 3c: R¹ = Ph; 3d: R¹ = SiMe₃; Ar = 2,6-(Me₂NCH₂)₂C₆H₃) were prepared by treatment of the (dichloromethyl)oligosilanes (Me₃Si)₂R¹Si–CHCl₂ (1a–d), with 2,6-bis(dimethylaminomethyl)phenyllithium (molar ratio 1:2). For 3c and 3d, X-ray structural analyses were performed indicating that only one dimethylamino group of the tridentate ligand is coordinated to the electrophilic silene silicon atoms, i.e., the central silicon atoms are tetracoordinated. The N → Si donation leads to pyramidalization at the silene silicon atoms; the configuration at the silene carbon atoms is planar. For a chemical characterization 3a and 3c were treated with water to give the silanols ArR¹Si(OH)–CH(SiMe₃)₂ (5a,c). Studies of the reactions of 3a and 3c with benzaldehyde, 4-chlorobenzaldehyde or 4-methoxybenzaldehyde, respectively, revealed an unexpected reaction path leading to the substituted 2-oxa-1-sila-1,2,3,4-tetrahydronaphthalenes 12a, 12c, 13 and 14. Both 12a and 12c were structurally characterized by X-ray analyses. The formation of these six-membered cyclic compounds, which is discussed in detail, gives support to a dipolar mechanism for the general reaction of silenes with carbonyl derivatives.     

Electronic absorption study on acid–base equilibria for some pyrimidine derivatives containing semi- and thiosemicarbazone moiety

The UV–vis spectra of recently synthesized 5-benzoyl-1-(methylphenylmethyleneamino)-4-phenyl-1H-pyrimidine-2-one, (I), and 5-benzoyl-1-(methylphenylmethyleneamino)-4-phenyl-1H-pyrimidine-2-thione, (II) were studied in aqueous methanol (5%, v/v methanol). The nature of the electronic transitions and the roles of carbonyl oxygen of I and thiocarbonyl sulfur of II on the behavior of UV–vis spectra were discussed.Acid–base equilibria of the compounds against varying pH and pK_a values related equilibria were determined at an ionic strength of 0.10 M by using the Henderson–Haselbalch equation. The mean acidity constants for the protonated forms of the compounds were determined as pK_a1 = 5.121, pK_a2 = 7.929 and pK_a3 = 11.130 for I and pK_a1 = 4.684, pK_a2 = 7.245 and pK_a3 = 10.630 for II. The preferred dissociation mechanisms were discussed based on UV–vis data and a mechanism was proposed for each compound.     

Chiral linear polymers bonded alternatively with salen and 1,4-dialkoxybenzene: synthesis and application for Ti-catalyzed asymmetric TMSCN addition to aldehydes

The synthesis of chiral linear polymers 1a–b having salen and 1,4-dioctyloxybenzene as alternate segments has been accomplished. The GPC analysis showed the molecular weights corresponding to ca. 15 (M_w = 10,999, M_n = 9165 and PDI = 1.20) repeating units for 1a and ca. 8 (M_w = 8547, M_n = 7883 and PDI = 1.08) repeating units for 1b. Polymers 1a–b have been studied with Ti(OⁱPr)₄ as a recyclable catalyst for the asymmetric addition of TMSCN to aldehydes while the selectivity of the polymer catalyst is identical to that of the monomer. The reactions are efficient affording the cyanohydrins with up to 88% ee. The selectivity of the polymer based catalyst 9a is found to be the same to that of the monomer 10a. The reaction provides the advantages of simplified product isolation and easy recovery and recyclability of polymer catalyst 9a without any loss of activity or selectivity.     

Anticancer and antimicrobial evaluation of newly synthesized steroidal 5,6 fused benzothiazines

A series of new 5α-cholestano [5,6-b] benzothiazines (4–6) has been synthesized by the reaction of 5α-cholestan-6-one (1–3) with 2-aminothiophenol in the presence of iodine. The structures of newly synthesized compounds have been established on the basis of spectral and analytical data. Compounds (1–6) were screened for in vitro anticancer activity against the human cancer cell lines; SW480 (colon adenocarcinoma cells), A549 (lung carcinoma cells), HepG2 (hepatic carcinoma cells) and HeLa (cervical cancer cells) using MTT assay during which the products (4–6) showed marked increase in anticancer activity and in particular, compound 6 showed IC₅₀ = 13.73 μmol L⁻¹ against HeLa cells, being more effective than Doxorubicin against the same cells. Compounds 4 and 6 also showed minimum IC₅₀ of 15.83 μmol L⁻¹ and 16.89 μmol L⁻¹ against HepG2 and A549 cells, respectively. Compounds (1–6) were also tested for in vitro antimicrobial activity against different bacterial as well as fungal strains during which newly synthesized compounds (4–6) were found more potent than starting compounds (1–3). Compound 4 was found to be more potent than the reference drug, Chloramphenicol, in the case of Escherichia coli while compound 5 was found almost equally potential antifungal agent against P. marneffei in comparison with the reference drug, Nystatin.     

Dialkyl- and diaryl-platinum(II) complexes with secondary phosphines: Preparation,structure and thermal reaction giving the metallopolymer

Alkyl and arylplatinum complexes with 1,5-cyclooctadiene ligand, [PtR₂(cod)] (R = Me, Ph, C₆H₄-p-CF₃, C₆F₅), react with secondary phosphines, PHR′₂ (R′ = i-Bu, t-Bu, Ph), to afford the mononuclear platinum complexes, cis-[PtR₂(PHR′₂)₂] (1a: R = Me, R′ = i-Bu; 1b: R = Me, R′ = t-Bu; 1c: R = Me, R′ = Ph; 2a: R = Ph, R′ = i-Bu; 2b: R = Ph, R′ = t-Bu; 2c: R = R′ = Ph; 3a: R = C₆H₄-p-CF₃, R′ = i-Bu; 3b: R = C₆H₄-p-CF₃, R′ = t-Bu; 3c: R = C₆H₄-p-CF₃, R′ = Ph; 4a: R = C₆F₅, R′ = i-Bu; 4c: R = C₆F₅, R′ = Ph) in 81–98% yields. Molecular structures of the complexes except for 1a, 1c and 2a were determined by X-ray crystallography. Complex 1b has a square-planar structure with Pt–C(methyl) bonds of 2.083(8) and 2.109(8) Å, while the Pt–C(aryl) bonds of 2b–c, 3a–c, 4a and 4c (2.055(1)–2.073(8) Å) are shorter than them. Thermal decomposition of 1b, 2a–c, and 3a–c releases methane, biphenyl or 4,4′-bis(trifluoromethyl)biphenyl as the organic products, which are characterized by NMR spectroscopy. The solid product of the thermal reactions of 2b and 2c were characterized as the metallopolymers formulated as [Pt(PR′₂)₂]_n (5b: R′ = ^tBu; 5c: R′ = Ph), based on the solid-state NMR and elemental analyses.     

Synthesis and characterization of thiosemicarbazone derivatives of 2-chloro-4-hydroxy-benzaldehyde and their rhenium(I) complexes

N-Thioamide thiosemicarbazone derived of 2-chloro-4-hydroxy-benzaldehyde (R = H, HL¹; R = Me, HL² and R = Ph, HL³) have been prepared and their reaction with fac-[ReX(CO)₃(CH₃CN)₂] (X = Br, Cl) in chloroform gave the adducts [ReX(CO)₃(HL)] (1a X = Cl, R = H; 1a′ X = Br, R = H; 1b X = Cl, R = CH₃; 1b′ X = Br, R = CH₃; 1c X = Cl, R = Ph; 1c′ X = Br, R = Ph) in good yield. Complexes 1a′ and 1b’ were also obtained by the reaction of HL¹ and HL³ with [ReBr(CO)₅] in toluene.All the compounds have been characterized by elemental analysis, mass spectrometry (FAB), IR and ¹H NMR spectroscopic methods. Moreover, the structures of HL², HL³ and 1a·H₂O were also established by X-ray diffraction. In 1a, the rhenium atom is coordinated by the sulphur and the azomethine nitrogen atoms, forming a five-membered chelate ring, as well as three carbonyl carbon and chloride atoms. The resulting coordination polyhedron can be described as a distorted octahedron.The study of the crystals obtained by slow evaporation of methanol and DMSO solutions of the adducts 1a′ and 1b, respectively, showed the formation of dimer structures based on rhenium(I) thiosemicarbazonates [Re₂(L¹)₂(CO)₆]·3H₂O (2a)·3H₂O and [Re₂(L²)₂(CO)₆]·(CH₃)₂SO (2b)·2(CH₃)₂SO. Amounts of these thiosemicarbazonate complexes [Re₂(L)₂(CO)₆] (2) were obtained by reaction of the corresponding free ligands with [ReCl(CO)₅] in dry toluene.In 2a·3H₂O and 2b·2(CH₃)₂SO the dimer structures are established by Re–S–Re bridges, where S is the thiolate sulphur from a N,S-bidentate thiosemicarbazonate ligand. In both structures the rhenium coordination sphere is similar; the dimers are in the same diamond Re₂S₂ face.     

Tuning the electronic properties of Fe2(μ-arenedithiolate)(CO)6−n(PMe3)n (n = 0, 2) complexes related to the [Fe–Fe]-hydrogenase active site

Complexes [Fe₂(μ-S₂Ar)(CO)₆] (S₂Ar) = benzene-1,2-dithiolate (1a) toluene-3,4-dithiolate (2a), 3,6-dichloro-1,2-benzenedithiolate (3a), quinoxaline-2,3-dithiolate (7a) have been prepared to investigate the electronic effect that different bridging arenedithiolate ligands have on the appended Fe₂(CO)₆ sites. Dinuclear complexes [Fe₂(μ-S₂Ar)(CO)₄(PMe₃)₂] (1–3,7)b and mononuclear complexes [Fe(S₂Ar)(CO)₂(PMe₃)₂] (1–3,7)c were synthesized from their parent hexacarbonyl complexes (1–3,7)a. IR spectroscopic, crystallographic and electrochemical analyses show that an increase of the electron-withdrawing character (where quinoxaline-2,3-dithiolate > 3,6-dichloro-1,2-benzenedithiolate > 1,2-benzenedithiolate ≥ toluene-3,4-dithiolate) of the bridging ligand leads to a decreased electron density at the iron centers, which yield a milder reduction potential and higher eCO stretching frequencies. This effect is coherent for all of the investigated complexes. Electrocatalytic proton reduction by complex 3a (with trifluoromethanesulfonic acid) was evidenced by cyclic voltammetry. As a result of the milder reduction potential of 3a itself, proton reduction that is promoted by 3a proceeds at a potential that is milder than that for the 1a-catalyzed process.     

Hybrid inorganic–organic frameworks containing magnesium: Synthesis and structures of magnesium squarate,diglycolate, and glutarate,and potassium magnesium cyclobutanetetracarboxylate

Four new magnesium containing metal–organic hybrid compounds have been synthesized in an effort to prepare low-density materials for hydrogen storage. The compounds were prepared hydrothermally and characterized using single crystal X-ray diffraction. Three of these compounds are analogs of known transition metal structures with squarate (I, Pn-3n, a = 16.276(5) Å), diglycolate (II, P2₁2₁2₁, a = 6.860(1) Å, b = 9.993(1) Å, c = 10.884(1) Å, R₁ = 0.0341), and glutarate (III, R-3, a = 10.744(2) Å, c = 28.677(5) Å, R₁ = 0.0554) ligands; the fourth is a novel structure using cyclobutanetetracarboxylate (IV, Pccn, a = 9.382(1) Å, b = 14.410(2) Å, c = 8.725(1) Å, R₁ = 0.0465) which contains potassium as well as magnesium cations.     

Synthesis and characterization of novel five-membered palladacycles

3-(2-Chloroquinolin-3-yl)-1,5-bis(3,4,5-trimethoxy-phenyl)-pentane-2,4-dione derivatives 3a–b were conveniently synthesized in excellent yields (82% each) by tandem Knoevenagel condensation reactions of 2-chloro-3-carbaldehyde-quinoline 1a–b with 3,4,5-trimethoxy acetophenone, followed by a base catalyzed Michael addition, such as DBU (1,8-diazabicyclo[5,4,0]undec-7-ene) with or without solvent. The reactions of 3a–b with Pd(dba)₂ in the presence of PPh₃ (1:2) in degassed acetone provided the dinuclear palladium complexes {Pd(C,N-2-C₉H₄N–CH–[–CH₂CO(3,4,5-(OMe-)₃–C₆H₂-]₂–3-R-6)Cl(PPh₃)}₂ [(R = H (4a), R = OMe (4b)] in moderate yields (38% and 43%), which in turn reacted with an excess of isonitrile XyNC (Xy = 2,6-Me₂C₆H₃) to give the corresponding palladacycles 5a–b in moderate yields (45% and 43%). The palladacycles 5a–b were also obtained in similar yields (32% and 33%) via a one-pot oxidative addition reaction of 3a-b with isonitrile XyNC:Pd(dba)₂ (4:1). The products were characterized by satisfactory elemental analysis and spectral studies (IR, ¹H, and ³¹P NMR). The crystal structure of 5a was determined by X-ray crystallography diffraction studies.     

Synthesis,characterization and X-ray crystal structure determination of cyclopalladated [Csp2,N,N′]−, zwitterionic and chelated compounds in the reaction of 3,5-diphenyl-N-alkylaminopyrazole derived ligands with Pd(II)

The synthesis of two N-alkylaminopyrazole ligands, 1-[2-(diethylamino)ethyl]-3,5-diphenylpyrazole (L1) and 1-[2-(dioctylamino)ethyl]-3,5-diphenylpyrazole (L2), is reported. These ligands present, a priori, one pyrazole nitrogen and one amine nitrogen as potential donor atoms. However, in the reaction of the ligands (L1 and L2) with [PdCl₂(CH₃CN)₂] one of the C_phenyl atoms can also behave as a donor atom. As a result, we have obtained the formation of three different compounds for each one of the ligands: chelated ([PdCl₂(L)] L = L1 (1a), L2 (2a)), zwitterionic ([PdCl₃(LH)] LH = LH1 (1b), LH2 (2b)), and cyclopalladated compounds ([PdCl(LC)] (LC = LC1 (1c), LC2 (2c)). The solid-state structures for 1a, 1b and 1c were determined by single crystal X-ray diffraction methods. The potentially [C,N,N′]^? ligand is coordinated through the N_pz and the N_amino to the metal atom for 1a, through the N_pz for 1b, and through the N_pz, the N_amino and a C_phenyl for 1c.     

Versatile Ru-based metathesis catalysts designed for both homogeneous and heterogeneous processes

The synthesis of new ruthenium-based catalysts applicable for both homogeneous and heterogeneous metathesis is described. Starting from the Hoveyda-Grubbs first generation (1) and the Hoveyda-Grubbs second generation (2) catalysts the homogeneous catalysts [RuCl((RO)₃Si–C₃H₆–N(R′)–CO–C₃F₆–COO)(CH–o-O–iPr–C₆H₄)(SIMes)] (4: R = Et, R′ = H; 5: R = R′ = Me) (SIMes = 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene) were prepared by substitution of one chloride ligand with trialkoxysilyl functionalized silver carboxylates (RO)₃Si–C₃H₆–N(R′)–CO–C₃F₆–COOAg (3a: R = Et, R′ = H; 3b: R = R′ = Me). These homogeneous ruthenium-species are among a few known examples with mixed anionic ligands. Exchange of both chloride ligands afforded the catalysts [Ru((RO)₃Si–C₃H₆–N(R′)–CO–C₃F₆–COO)(CH–o-O–iPr–C₆H₄)(SIMes)] (9: R = Et, R′ = H; 11: R = R′ = Me) and [Ru((RO)₃Si–C₃H₆–N(R′)–CO–C₃F₆–COO)(CH–o-O–iPr–C₆H₄)(PCy₃)] (8: R = Et, R′ = H; 10: R = R′ = Me). The reactivity of the new complexes was tested in homogeneous ring-closing metathesis (RCM) of N,N-diallyl-p-toluenesulfonamide and TONs of up to 5000 were achieved. Heterogeneous catalysts were obtained by reaction of 4, 5 and 8–11 with silica gel (SG-60). The resultant supported catalysts 4a, 5a, 8a–11a showed reduced activity compared to their homogenous analogues, but rival the activity of similar heterogeneous systems.     

Enantioselective 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds catalyzed by rhodium(I)-chiral phosphoramidite complexes

A chiral bidentate phosphoramidite (5a) was synthesized from Shibasaki’s linked-(R)-BINOL and P(NMe₂)₃ as a new ligand for rhodium(I)-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds. The effects of 5a and Feringa’s monodentate phosphoramidite (4, R¹, R² = Et) on the yields and enantioselectivities were fully investigated. The reaction was significantly accelerated in the presence of a base such as KOH and Et₃N, allowing the reaction to be completed at the lower temperatures than 50 °C. The addition to cyclic enones such as 2-cyclopentenone, 2-cyclohexenone and 2-cycloheptenone at 50 °C in the presence of an [Rh(coe)₂Cl]₂-4 (R¹, R² = Et) complex resulted in enantioselectivities up to 98%, though it was less effective for acyclic enones (0–70% ee). On the other hand, a complex between [Rh(nbd)₂]BF₄ and 5a completed the addition to cyclic enones within 2 h at room temperature in the presence of Et₃N with 86–99% yields and 96–99.8% ee. This catalyst was also effective for acyclic enones, resulting in 62–98% yields and 66–94% ee. The 1,4-additions of arylboronic acids to unsaturated lactones and acyclic esters with rhodium(I)-phosphoramidites complexes were also investigated.     

Palladium(II) complexes with the new P,N-type ligand (2-oxazoline-2-ylmethyl)di-isopropylphosphine as intermediates in CO/ethylene or CO/methyl acrylate insertion

The ligand (i-Pr)₂PCH₂(oxazoline) (1a), of the P,N-donor type, was reacted with [PdMeCl(COD)] to yield the square planar methylpalladium(II) complex [PdClMe(P,N)] (P,N = 1a) (2a), from which the complex [PdMe(P,N)OTf] (OTf = OSO₂CF₃) (3a) was obtained by AgOTf-promoted chloride abstraction. The alkyl complexes

(P,N = 1a) (5a, R = H; 7a, R = C(O)OMe) have been isolated from the initial CO/ethylene or CO/methyl acrylate insertion steps into the Pd–Me bond of 3a, respectively, and spectroscopically characterized. Complexes 2a, 3a and 7a have been fully characterized by single crystal X-ray diffraction. Complex 7a is still a rare example of a structurally characterized CO/methyl acrylate stepwise insertion product. These complexes are relevant to the alternating copolymerization of olefins and carbon monoxide catalyzed by palladium complexes. In addition, the centrosymmetric dinuclear complex trans-[Pd(μ-Cl){(i-Pr)₂PCH₂(oxazoline)}]₂(OTf)₂ (6) has been obtained and characterized by X-ray diffraction; it appears to be the first dinuclear complex of the type [Pd(μ-Cl)(P,N)]₂ to be characterized by X-ray crystallography.

Résumé

Le ligand (i-Pr)₂PCH₂(oxazoline) (1a), de type donneur P,N, réagit avec [PdClMe(COD)] pour former le complexe plan carré méthylpalladium(II) [PdClMe(P,N)] (P,N = 1a) (2a), à partir duquel le complexe [PdMe(P,N)OTf] (OTf = OSO₂CF₃) (3a) a été obtenu par abstraction de chlorure à l'aide de AgOTf. Les complexes alkyles

(P,N = 1a) (5a, R = H; 7a, R = C(O)OMe), ont été isolés lors des premières étapes d'insertion de CO/éthylène ou de CO/acrylate de méthyle, respectivement, dans la liaison Pd–Me de 3a, et caractérisés par méthodes spectroscopiques. Les complexes 2a, 3a et 7a ont été complètement caractérisés par diffraction des rayons X sur monocristal. Le complexe 7a est un exemple encore rare de produit d'insertion par étapes de CO/acrylate de méthyle qui ait été caractérisé structuralement. Ces complexes sont pertinents pour la copolymérisation alternée d'oléfines et de monoxyde de carbone catalysée par les complexes du palladium. En outre, le complexe dinucléaire centrosymétrique trans-[Pd(μ-Cl){(i-Pr)₂PCH₂(oxazoline)}]₂(OTf)₂ (6) a été obtenu et caractérisé par diffraction des rayons X; il s'agit du premier complexe dinucléaire de type [Pd(μ-Cl)(P,N)]₂ à être caractérisé par diffraction des rayons X.     

Synthesis and X-ray structures of heptanuclear and decanuclear mixed-metal sulfido clusters containing noble metals and Group 15 metals

Reactions of incomplete cubane-type clusters [(Cp°RuCl)₂(μ-SH)(μ-SM′Cl₂)] (M′ = Sb (2a), Bi; Cp° = η⁵-C₅Me₄Et) with 0.5 equiv of [PdCl₂(cod)] (cod = 1,5-cyclooctadiene) afforded the corner-shared double cubane-type clusters [{(Cp°Ru)(Cp°RuCl)(μ-SM′Cl₂)}₂(μ₃-S)₂(μ-Cl)₂Pd] (3a: M′ = Sb, 3b: M′ = Bi) in moderate yields, whereas treatment of 2a with 0.75 equiv of [PdCl₂(cod)] gave the corner-shared triple cubane-type cluster [{(Cp°Ru)(Cp°RuCl)(μ-SSbCl₂)(μ₃-S)₂(μ-Cl)₂Pd}₂(Cp°Ru)₂] (4). Single-crystal X-ray analyses have disclosed the detailed structures of novel heptanuclear and decanuclear mixed-metal cores for 3a and 4, respectively.     

Catalytic asymmetric cyano-phosphorylation of aldehydes using a YLi3tris(binaphthoxide) complex (YLB)

A highly enantioselective cyano-phosphorylation of aldehydes catalyzed by a YLi₃tris(binaphthoxide) complex YLB 1 is described. The slow addition of diethyl cyanophosphonate 4 to aldehydes 5 in the presence of YLB 1 (10 mol %), H₂O (30 mol %), tris(2,6-dimethoxyphenyl)phosphine oxide 3a (10 mol %), and BuLi (10 mol %) afforded cyanohydrin O-phosphates 6 in up to 98% yield and 97% ee. Mechanistic studies revealed that the addition of cyanide to aldehydes is irreversible and determines the enantioselectivity. The reaction mechanism is also discussed in detail.