New chiral phosphine-phosphonites derived from (2R,3R)-dimethyl tartrate, (S)-binaphthol and (1R,2S)-ephedrine

The reaction of 2-lithiophenyldiphenylphosphine with phosphorus trichloride afforded the new unsymmetric phosphine, dichloro(2-diphenylphosphinophenyl)phosphine (4). Condensation of 4 with (a) (2R,3R)-dimethyl tartrate or (b) (S)-binaphthol in the presence of triethylamine gave new chiral phosphine-phosphonite ligands, (2R,3R)-[2-(2′-(diphenylphosphino)phenyl)-4,5-bis(carbomethoxy)-1,3,2-dioxaphospholane] ((2R,3R)-5) and (S)-[2-(diphenylphosphino)benzene][1,1′-binaphthalen-2,2′-diyl]phosphonite] ((S)-6). The analogous reaction of 4 with (1R,2S)-ephedrine using N-methylmorpholine as the base, gave [2-(2′-(diphenylphosphino)phenyl)-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine] (7) as a 95:5 mixture of diastereoisomers.     

A mild and efficient cyanosilylation of ketones catalyzed by a Lewis acid-Lewis base bifunctional catalyst

A new family of bifunctional catalysts (N-oxides-Ti(OⁱPr)₄ (2:1)) containing a Lewis acid and a Lewis base was developed and applied to the catalytic cyanosilylation of ketones. Utilizing rac((1R,2S) and (1S,2R))-1-(2′-pyridylmethyl)-2-diphenylhydroxymethylpyrrolidine N-oxide-titanium (2:1) complex and N-benzyl-diethanolamine N-oxide-titanium (2:1) complex as catalysts, the cyanosilylation products were obtained in 42-97% yield. Based on experimental phenomena and kinetic studies, a catalytic cycle was proposed to explain the remarkable activities of these catalysts. Investigations indicated that rac((1R,2S) and (1S,2R))-1-(2′-pyridylmethyl)-2-diphenylhydroxymethylpyrrolidine N-oxide-titanium (2:1) complex and N-benzyl-diethanolamine N-oxide-titanium (2:1) complex should promote the reaction via a dual activation of the ketone by the titanium and TMSCN by the N-oxide.     

Haloalkyl complexes of the transition metals: IV. The formation of a cationic ylide complex of platinum(II) from a chloromethylplatinum(II) complex and the crystal structures of cis-[Pt(CH2PPh3)X(PPh3)2]I (X = Cl or I)

The reactions of Pt(PPH₃)₄ and Pt(C₂H₄)(PPh₃)₂ with CH₂ClI have been investigated. The product of the reaction of Pt(PPh₃)₄ with CH₂ClI is the cationic ylide complex cis-[Pt(CH₂PPh₃)Cl(PPh₃)2][I], whereas the reaction of Pt(C₂H₄)-(PPh₃)₂ gives the oxidative addition product Pt(CH₂Cl)I(PPh₃)₂. Reaction of cis- or trans-Pt(CH₂Cl)I(PPh₃)₂] with PPh₃ gives the complex cis-[Pt(CH₂PPh₃)-Cl(PPh₃)₂][I]. The structures of the complexes cis-[Pt(CH₂PPh₃X(PPh₃)₂][I] (where X = Cl or I) have been determined by X-ray crystallography. Both complexes crystalize in the monoclinic space group P2₁/n. For X = Cl a 1388.6(7), b 2026.7(10), c 1823.9(9) pm, β 96.51(2)° and R converged to 0.075 for 3542 observed reflections; structural parameters Pt-Cl 240(1), Pt-C(3) 212(2), Pt-P(2) (trans to Cl) 235(1) and Pt-P(1) (trans to CH₂PPh₃) 233(1) pm; Cl-Pt-C(3) 86.9(5), C(3)-Pt-P(2) 91.8(5), P(2)-Pt-P(1) 97.0(2) and P(1)-Pt-Cl 85.1(2)°. For X = I, a 1379.4(7), b 2044.4(10), c 1840.0(9) pm, β 96.09(2)° and R converged to 0.071 for 4333 observed reflections; structural parameters Pt-I 266(1), Pt-C(3) 212(2), Pt-P(2) (trans to I) 226(1) and Pt-P(1) (trans to CH₂PPh₃ 233(1) pm; I-Pt-C(3) 87.2(5), C(3)-Pt-P(2) 91.5(5), P(2)-Pt-P(1) 96.5(2) and P(1)-Pt-I 85.6(1)°. Some other complexes of the type cis-[Pt(CH₂PPh₃)X(PPh₃)₂]Y are also described.     

2-Acetylpyridine- and 2-benzoylpyridine-derived thiosemicarbazones and their antimony(III) complexes exhibit high anti-trypanosomal activity

Complexes [Sb(2Ac4oClPh)Cl₂] (1), [Sb(2Ac4oFPh)Cl₂] (2), [Sb(2Ac4oNO₂Ph)Cl₂] (3), [Sb(2Bz4oClPh)Cl₂] (4), [Sb(2Bz4oFPh)Cl₂] (5) and [Sb(2Bz4oNO₂Ph)Cl₂] (6) were obtained with 2-acetylpyridine-N(4)-ortho-chlorophenyl thiosemicarbazone (H2Ac4oClPh) and its N(4)-ortho-fluor (H2Ac4oFPh) and N(4)-ortho-nitro (H2Ac4oNO₂Ph) analogues, and with the corresponding 2-benzoylpyridine-derived thiosemicarbazones (H2Bz4oClPh, H2Bz4oFPh, H2Bz4oNO₂Ph). The studied compounds are excellent inhibitors of Trypanosoma cruzi growth. H2Bz4oClPh and complexes (4) and (1) were the most trypanosomicidal.Upon coordination of H2Ac4oClPh to antimony(III) in 1, the therapeutic index (TI) goes from 10.58 to 14.35. However, the best values of TI were found for H2Bz4oClPh (TI = 1240) and H2Ac4oNO₂Ph (TI = 773). Structure-activity relationship (SAR) studies did not allow the establishment of correlations between the anti-trypanosomal activity and physico-chemical parameters, but correlations were found between the cytotoxicities and physico-chemical properties.     

Solid-state structure determination and solution-state NMR characterization of the (2R,4R)/(2S,4S)- and (2R,4S)/(2S,4R)-diastereomers of the agricultural fungicide propiconazole,the (2R,4S)/(2S,4R)-symmetrical triazole constitutional isomer,and a ditriazole analogue

Single-crystal X-ray diffraction analysis was used to determine the structure of a racemic diastereomer of the agricultural fungicide propiconazole [1-(2-(2,4-dichlorophenyl)-4-n-propyl-1,3-dioxolane-2-yl-methyl)-1-H-1,2,4-triazole] and of two by-products (a symmetrical 1,3,4-triazole racemic-constitutional isomer and a propiconazole ditriazole analogue). All three crystalline racemic-diastereomers had (2R,4S)/(2S,4R)-stereochemistry in which then-propyl group was observed in atrans-to-phenyl disposition. Propiconazole (2R,4S)/(2S,4R)-diastereomer gives crystals belonging to the monoclinic space group P2₁,/a, and, at 293 K,a=8.1192(3),b=18.9769(6),c=10.7137(4) å,Β=99.765(3)?,V=1626.8(1) å³, Z=4,R(F)=0.060, andR _w(F)=0.058. The constitutional isomer by-product (2R,4S)/(2S,4R)-1-(2-(2,4-dichlorophenyl)-4-n-pro-pyl-1,3-dioxolane-2-yl-methyl)-1-H-1,3,4-triazole gives crystals belonging to the monoclinic space group P2₁/n, and, at 293 K,a=11.1763(6),b=10.7716(4),c=14.5804(8) å,Β=107.445(4)?,V=1674.6(1) å³, Z=4,R(F)=0.043, andR _w(F)=0.043. The ditriazole byproduct (2R,4S)/(2S,4R)-1-(2-(2-chloro-4-(1,2,4-triazole-1-yl)phenyl)-4-n-propyl-1,3-dioxolane-2-yl-methyl)-1-H-1,2,4-triazole gives crystals belonging to the triclinic space groupP¯ 1, and, at 193 K,a=5.3329(8),b=8.3738(7),c=20.240(2) å, α=84.213(6)?,Β=87.20(1)?,γ=86.23(1)?,V=896.5(2) å³, Z=2,R(F)=0.046, andR _w(F)=0.051. The presence of both propiconazole (2R.4S)- and (2S,4R)-enantiomers enables the formation of a crystalline racemic modification, while the diastereomeric propiconazole (2R,4R)- and (2S,4S)-enantiomers are viscous oils. In the absence of its enantiomorphic partner, the propiconazole (2R,4S)- or (2S,4R)-enantiomers remain as viscous oils rather than form chiral crystals.     

Die Struktur von Cp2TiMe2

The structure of dimethyltitanocene, Cp₂TiMe₂, has been determined: monoclinic, space group P2₁/n, lattice constants (at −100°C) a = 6.818(2), b = 11.571(2), c = 13.387(3) Å, β = 92.36(2)°, and Z = 4. It is isostructural with Cp₂ZrMe ₂ and Cp₂HfMe₂. The Ti-C(σ) bond lengths are 2.170(2) and 2.181(2) Å and the C(σ)-Ti-C(σ) angle is 91.3(1 )°.     

Phenylmercury dithiolates. The crystal and molecular structures of (C6H5Hg(S2COR) (R = Me; iPr and (C6H5)Hg(S2CNEt2))

The preparation, spectroscopic characterization, and X-ray structures of a number of phenylmercury dithiolates (xanthate and dithiocarbamate) are reported. The solid state structures feature monodentate dithiolate ligands and approximate linear geometries about the mercury atoms. The HgS distances fall within the relatively narrow range of 2.374(4)–2.388(2) Å in these compounds. The presence of additional Hg ⋯ S contacts also characterize these structures; the number and strength of these interactions depending on the nature of the dithiolate ligand. Crystals of PhHg(S₂COMe) are monoclinic, space group C2/c with unit cell dimensions a 37.73(2), b 4.825(1), c 12.686(1) Å, β 101.21(2)° with Z = 8; PhHg(S₂COⁱPr) crystallizes in the monoclinic space group P2₁/a with a 13.678(5), b 21.347(7), c 14.570(6) Å, β 114.99(2)° and Z = 12; and crystals of PhHg(S₂CNEt₂) are triclinic, P1, with cell parameters a 9.959(2), b 12.359(4), c 13.098(2) Å, α 65.53(2), β 65.81(2), γ 81.26(2)° and Z = 4. Refinement on 777 reflections [with I ≥ 3.0σ(I)] converged with final R 0.096 and R_w 0.090 for PhHg(S₂COMe); 2888 reflections [I ≥ 2.5 σ(I)], R 0.033, R_w 0.038 for PhHg(S₂COⁱPr); 2675 reflections [I ≤ 2.5 σ (I)], R, 0.033, R_w 0.038 for PhHg(S₂CNEt₂).     

An efficient and stereodivergent synthesis of threo- and erythro-β-methylphenylalanine. Resolution of each racemic pair by semipreparative HPLC

threo and erythro diastereoisomers of the constrained amino acid (βMe)Phe can be obtained separately on a multigram scale through a three-step synthesis from the corresponding Z and E isomers of 2-phenyl-4(α-phenylethylidene)-5(4H)-oxazolone. The 5(4H)-oxazolones are readily available from acetophenone and hippuric acid. The four enantiomerically pure isomers of β-methylphenylalanine, (2R,3R)-(βMe)Phe, (2S,3S)-(βMe)Phe, (2R,3S)-(βMe)Phe and (2S,3R)-(βMe)Phe, have been prepared by HPLC resolution of the racemic precursors methyl threo (or erythro)-2-benzamide-3-phenylbutanoates.     

Synthesis of the dibenzo[f,h]phthalazine and dibenzo[f,h]cinnoline skeleton via a ‘Suzuki-Pd-catalyzed intramolecular arylation’ and a ‘Suzuki-Pschorr’ approach

Palladium-catalyzed intramolecular arylation of 2-benzyl-5-(2-bromophenyl)-4-phenylpyridazin-3(2H)-one yielded hitherto unknown 2-benzyldibenzo[f,h]phthalazin-1(2H)-one. The synthesis of this new tetracyclic pyridazinone from 2-benzyl-5-(2-aminophenyl)-4-phenylpyridazin-3(2H)-one via a Pschorr type reaction was also investigated. Similarly, the construction of 2-methyldibenzo[f,h]cinnolin-3(2H)-one from 2-methyl-5-(2-bromophenyl)-6-phenylpyridazin-3(2H)-one and 2-methyl-5-(2-aminophenyl)-6-phenylpyridazin-3(2H)-one is also reported. Removal of the N-benzyl protective group of 2-benzyl-dibenzo[f,h]phthalazin-1(2H)-one with AlCl₃ yielded unsubstituted dibenzo[f,h]phthalazin-1(2H)-one.     

5-phenyl-2H-tetrazol-2-ylmethyl ketones in the synthesis of tetrazolylalkanols and tetrazolyl(hydroxy)alkylphosphonates

The reduction of 1-(5-phenyl-2H-tetrazol-2-yl)propan-2-one and 1-phenyl-2-(5-phenyl-2H-tetrazol-2-yl)ethanone with sodium tetrahydridoborate gave 1-(5-phenyl-2H-tetrazol-2-yl)propan-1-ol and 1-phenyl-2-(5-phenyl-2H-tetrazol-2-yl)ethanol, respectively. Only 1-(5-phenyl-2H-tetrazol-2-yl)propan-2-one was reduced with baker’s yeast with an appreciable yield. 1-(5-Phenyl-2H-tetrazol-2-yl)propan-2-one and 1-phenyl-2-(5-phenyl-2H-tetrazol-2-yl)ethanone reacted with diethyl phosphonate in the presence of potassium fluoride to produce the corresponding diethyl [hydroxy(5-phenyl-2H-tetrazol-2-yl)alkyl]phosphonates.     

Synthesis,spectral and structural studies of a Mn(II) complex of [N′-(pyridine-4-carbonyl)-hydrazine]-carbodithioic acid ethyl ester and Mn(II) and Ni(II) complexes of [N′-(pyridine-4-carbonyl)-hydrazine]-carbodithioic acid methyl ester

The new complexes [Mn(Hpchce)₂(o-phen)], {2[Mn(pchcm)(o-phen)₂]}·7H₂O and [Ni(Hpchcm)(o-phen)₂]Cl·CH₃OH with [N′-(pyridine-4-carbonyl)-hydrazine]-carbodithioic acid ethyl ester (H₂pchce) and [N′-(pyridine-4-carbonyl)-hydrazine]-carbodithioic acid methyl ester (H₂pchcm) have been synthesized, containing o-phenanthroline (o-phen) as a coligand. These ligands and their complexes have been characterized by elemental analyses, IR, magnetic susceptibility and single crystal X-ray data. H₂pchce (2), [Mn(Hpchce)₂(o-phen)] (3) {2[Mn(pchcm)(o-phen)₂]}·7H₂O (4) and [Ni(Hpchcm)(o-phen)₂]Cl·CH₃OH (5) crystallized in the monoclinic system, space group Pc, C2/c, P21/n and P21/n, respectively. The (N, O) donor sites of the bidentate ligands chelate the Mn(II) and Ni(II) centers forming a five-membered CN₂OM ring. The resulting complexes are paramagnetic and have a distorted octahedral geometry.     

Monomeric five-coordinate rhenium diazenido and hydrazido complexes with aromatic thiolate ligands: X-ray structures of [Re(NNC6H4-Br)2(SC6H3-2,5-Me2)(PPh3)2] and [ReO(NNMePh)(SPh)3], and of the synthetic precursor [Re(NNC6H4-4-Br)2Cl(PPh3)2]

Reaction of [ReOCl₃(PPh₃)₂] with bromophenylhydrazine in methanol yields [ReCl(N₂C₆H₄Br)₂(PPh₃)₂] (1). Complex 1 reacts with arylthiolates to give mixtures of [Re(SAr)(N₂C₆H₄Br)₂(PPh₃)₂] (2) and [Re₂(SAr)₇(NNR)₂]⁻. Complexes 1 and 2 display trigonal bipyramidal geometries with the phosphine ligands occupying the axial sites. A significant feature of the structures is the nonequivalence of the rhenium-diazenido moieties, such that for 1 the ReN(1) and N(1)N(2) distances are 1.80(2) and 1.24(3) Å, while ReN(3) and N(3)N(4) are 1.73(2) and 1.32(3) Å, and for 2 the ReN distances are 1.73(1) and 1.80(2)° with corresponding NN distances of 1.32(2) and 1.25(2) Å. Reaction of (PPh₄)[ReO(SPh)₄] (3) with unsymmetrically disubstituted hydrazines affords complexes of the type [ReO(SPh)₃(NMRR′)] (R = Me, R′ = Ph for 4). Complexes 3 and 4 display distorted square pyramidal geometries with the oxo groups apical. The significant feature of the structure of 4 is the nonlinear ReN(1)N(2) linkage, exhibiting an angle of 145.6(10)°. The angle does not appear to correlate with a significant contribution from a valence form with sp² hybridization at the α-nitrogen. Crystal data: 1: monoclinic space group, P2₁/n, a = 12.216(2) Å, b = 19.098(2) Å, c = 20.257(4) Å, β = 106.20(1)°, V = 4538.3(8) ų to give Z = 4; structure solution and refinement based on 1905 reflections converged at R = 0.070. 2: monoclinic space group P2₁/n, a = 14.393(2) Å, b = 18.842(3) Å, c = 20.717(4)Å, β = 110.26(1)°, V = 5270.5(8) ų to give Z = 4 for D = 1.53 g cm⁻¹; structure solution and refinement based on 4249 reflections to give R = 0.070. 3: monoclinic space group P2₁/n, a = 12.531(2) Å, b = 24.577(4) Å, c = 16.922(3) Å, β = 99.06(1)°, V = 5146.2(9) ų, D = 1.36 g cm⁻³ for Z = 4, 2912 reflections, R = 0.050. 4: monoclinic space group p2₁/n, a = 16.137(2) Å, b = 9.863(2) Å, c = 16.668(2) Å, β = 111.12(1)°, V = 2474.7(6) ų, D = 1.74 g cm⁻³ for Z = 4, 2940 reflections, R = 0.066.     

Studies on ion association. Calorimetric study of the formation of monoazido complexes of Ni(II), Zn(II) and Cd(II)

From rehydration experiments the hydrates Ba(OH)₂ · 8 H₂O, Ba(OH)₂ · 3 H₂O β-Ba(OH)₂, · 1 H₂O, and γ-Ba(OH)₂ · 1 H₂O have been found in the system Ba(OH)₂-H₂O. Thermoanalytical measurements (DTA, TG, DTG, high temperature X-ray diffraction, high temperature Raman scattering) on these hydrates are reported. Thermal decomposition of Ba(OH)₂ · 8 H₂O and Ba(OH)₂ · 3 H₂O always results in the formation of β-Ba(OH)₂ · 1 H₂O, the stable form of the monohydrates at ambient temperature. Dehydration of β- and γ-Ba(OH)₂ · 1 H₂O, both of which form anhydrous β-Ba(OH)₂ as the first product of decomposition, starts at 105 and 115°C, respectively. Single crystals of Ba(OH)₂ · 3 H₂O and γ-Ba(OH)₂ · 1 H₂O were prepared from Ba(OH)₂ · 8 H₂O meltings and from ethanolic solutions of Ba(OH)₂ , respectively. The crystal data are: Ba(OH)₂ · 3 H₂O (orthorhombic, Pnma): a = 764.0(2), b = 1140,3(5), c = 596.5(1) pm, Z = 4; γ-Ba(OH)₂ · 1 H₂O (monoclinic, P2₁/m or P2₁): a = 704.9(2), b = 418.4(1), c = 633.3(1) pm, β = 111.45(2)°, Z = 2.     

Crystal structures of azido or thiocyanato-coordinated nickel(II) complexes with tridentate Schiff bases

A new azido-coordinated nickel(II) complex [NiL¹(N₃)] (1) and a new thiocyanato-coordinated nickel(II) complex [NiL²(NCS)] (2), where L¹ and L² are the monoanionic forms of Schiff bases 2-[(2-isopropylaminoethylimino)methyl]-6-methylphenol and 2-[(2-dimethlaminoethylimino)methyl]-6-methylphenol respectively, are prepared and structurally characterized by elemental analysis, IR spectra, and single crystal X-ray crystallography. Complex 1 crystallizes in the triclinic space group P-1 with unit cell dimensions a = 8.812(2) Å, b = 9.433(3) Å, c = 9.488(2) Å, α = 81.933(2)°, β = 69.925(2)°, γ = 84.591(2)°, V = 732.5(3) ų, Z = 2, R ₁ = 0.0291, and wR ₂ = 0.0734. Complex 2 crystallizes in the monoclinic space group P2₁/n with unit cell dimensions a = 7.4497(4) Å, b = 6.1933(3) Å, c = 31.5126(18) Å, β = 92.484(2)°, V = 1452.57(13) ų, Z = 4, R ₁ = 0.0307, and wR ₂ = 0.0668. The Ni atom in each of the complexes is coordinated by three donor atoms of the Schiff base ligand and by one N atom of the azide or thiocyanate ligand, forming a square planar geometry. The azide and thiocyanate anions readily coordinate to the complexes as secondary ligands.     

Lanthanide N,N′-piperazine-bis(methylenephosphonates) (Ln=La, Ce, Nd) that display flexible frameworks, reversible hydration and cation exchange

Hydrothermal syntheses of lanthanide bisphosphonate metal organic frameworks comprising the light lanthanides lanthanum, cerium and neodymium and N,N′-piperazine bis(methylenephosphonic acid) (H₂L(1) and its 2-methyl and 2,5-dimethyl derivatives (H₂L(2) and H₂L(3)) gives three new structure types. At elevated starting pH (ca. 5 and above) syntheses give ‘type I’ materials with all metals and acids of the study (MLnLxH₂O, M=Na, K, Cs; Ln=La, Ce, Nd; x≈4: KCeL(1)·4H₂O, C2/c, a=23.5864(2) Å, b=12.1186(2) Å, c=5.6613(2) Å, β=93.040(2)°). The framework of structure type I shows considerable flexibility as the ligand is changed, due mainly to rotation around the -N-CH₂- bond of the linker in response to steric considerations. Type I materials demonstrate cation exchange and dehydration and rehydration behaviour. Upon dehydration of KCeL·4H₂O, the space group changes to P2₁/n, a=21.8361(12) Å, b=9.3519(4) Å, c=5.5629(3) Å, β=96.560(4)°, as a result of a change of the piperazine ring from chair to boat configuration. When syntheses are performed at lower pH, two other structure types crystallise. With the ‘non-methyl’ ligand 1, type II materials result (LnL(1)H₂L(1)·4.5H₂O: Ln=La, P−1, a=5.7630(13) Å, b=10.213(2) Å, c=11.649(2) Å, α=84.242(2)°, β=89.051(2)°, γ=82.876(2)°) in which one half of the ligands coordinate via the piperazine nitrogen atoms. With the 2-methyl ligand, structure type III crystallises (LnHL(2)·4H₂O: Ln=Nd, Ce, P2₁/c, a=5.7540(9) Å, b=14.1259(18) Å, c=21.156(5) Å, β=90.14(2)°) due to unfavourable steric interactions of the methyl group in structure type II.     

Chemical behavior of ortho-hydroquinone-based bis(pyrazol-1-yl)methane ligands in the presence of palladium(II) chloride

The synthesis, structural characterization, and coordination behavior of ditopic ortho-hydroquinone-based bis(pyrazol-1-yl)methane ligands (ortho-(OH)₂C₆H₃-4-CHpz₂, ortho-(OH)₂C₆H₃-4-CH(3-Phpz)₂, and ortho-(OH)₂C₆H₃-4-CH(3-tBupz)₂) with pyrazole, 3-phenylpyrazole, and 3-tert-butylpyrazole as donors are described. The reaction of a soluble PdCl₂-source with ortho-(OH)₂C₆H₃-4-CHpz₂ in acetonitrile yielded the related square-planar N,N-coordinated Pd(II) dichloride complex, whereas treatment of ortho-(OH)₂C₆H₃-4-CH(3-Phpz)₂ or ortho-(OH)₂C₆H₃-4-CH(3-tBupz)₂ with PdCl₂ in acetonitrile resulted in degradation of these ligands. The Pd(II) complexes trans-(3-PhpzH)₂PdCl₂ and trans-(3-tBupzH)₂PdCl₂ were isolated and fully characterized including X-ray diffraction analyses.     

Crystal structures of new isostructural oxovanadium(V) complexes with hydrazone ligands

Two new isostructural methoxide-bridged dimeric oxovanadium(V) complexes [VO(L¹)(OMe)]₂ (1) and [VO(L²)(OMe)]₂ (2), where L¹ and L² are the deprotonated forms of 3-bromo-N′-[1-(2-hydroxyphenyl)×ethylidene]benzohydrazide (H₂L¹) and 3-chloro-N′-[1-(2-hydroxyphenyl)ethylidene]benzohydrazide (H₂L²) respectively, are synthesized and characterized by elemental analyses, IR spectra, and single crystal X-ray determination. Both crystals crystallize in the triclinic space group P-1. For 1, a = 7.5237(15) Å, b = 10.846(3) Å, c = 11.195(3) Å, α = 84.143(3)°, β = 72.244(3)°, γ = 77.869(3)°, V = 849.9(4) ų, Z = 1, R ₁ = 0.0634, wR ₂ = 0.1373. For 2, a = 7.493(2) Å, b = 10.740(3) Å, c = 11.109(3) Å, α = 84.569(2)°, β = 71.783(2)°, γ = 79.822(2)°, V = 835.0(4) ų, Z = 1, R ₁ = 0.0511, wR ₂ = 0.1076. Each V atom in the complexes is octahedrally coordinated.     

Synthesis and X-ray structure of two isomeric aminocarbene complexes of tungsten containing a free carbon-carbon double bond

The reaction of allylamine with (CO)₅WC(OCH₂CH₃)CH₃ gives two isomeric aminocarbene complexes (CO)₅WC(NHCH₂CHCH₂)CH₃ 2E and 2Z. Refluxing of a solution of this mixture in benzene gives the complexes (CO)₄WC(η²NHCH₂CHCH₂)CH₂ (3) and 2E, which have been separated. 2E was fully characterized by X-ray diffraction. Crystals of 2E are monoclinic, space group P2₁/n with Z = 4, a 7.188(3), b 14.312(2), c 12.530(2) Å and β 91.06(3)°.The same mixture when treated with lithium diisopropylamide (LDA) followed by allyl bromide gives a mixture of (CO)₅WC(N(CH₂CHCH₂)₂)CH₃ (4) and 2Z. These complexes were separated, and 2Z fully characterized by X-ray diffraction. Crystals of 2Z are monoclinic, space group P2₁/c, with Z = 4, a 6.593(5), b 14.584(3), c 13.323(1) Å and β 95.13(4)°.     

Microwave-assisted synthesis of N,N-bis-(2-pyridylmethyl)amine derivatives. Useful ligands in coordination chemistry

Microwave-assisted synthesis of the ligands N,N-bis-(2-pyridylmethyl)amine (BMPA), N-(methylpropanoate)-N,N-bis-(2-pyridylmethyl)amine (MPBMPA), N-(propanamide)-N,N-bis-(2-pyridylmethyl)amine (PABMPA), PNBMPA (N-(3-propionitrile)-N,N-bis-(2-pyridylmethyl)amine), N-(3-aminopropyl)-N,N-bis-(2-pyridylmethyl)amine (APBMPA), and lithium N-(proponoate)-N,N-bis-(2-pyridylmethyl)amine (LiPBMPA) are reported. High yields and short reaction time were obtained for condensation and Michael addition.     

Efficient synthesis and resolution of novel 2-(hydroxymethyl)-7,8-dihydro-1H-indeno[5,4-b] furan-6(2H)-one by lipase Pseudomonas cepacia

Lipase Pseudomonas cepacia catalyzed acylation of (±)-2-(hydroxymethyl)-7,8-dihydro-1H-indeno[5,4-b] furan-6(2H)-one using vinyl acetate as the acyl donor in acetone gave (−)-(R)-2-acetoxy-2-(methyl)-7,8-dihydro-1H-indeno[5,4-b] furan-6(2H)-one and (+)-(S)-2-(hydroxymethyl)-7,8-dihydro-1H-indeno[5,4-b] furan-6(2H)-one with high enantiomeric excess. Enantiomerically pure 2-(hydroxymethyl)-7,8-dihydro-1H-indeno[5,4-b] furan-6(2H)-one are useful intermediates for the preparation of Ramelteon, an FDA approved drug for the treatment of insomnia.