Zur Bildung von Xylol-tricarbonylchrom (Dimethylbenchrotrenen) aus Di-n-butylether und Hexacarbonylchrom

The reaction of fluorenone ethyleneketal (9), diphenic anhydride as well as of biphenyls such as4 with Cr(CO)₆ in refluxing di-n-butylether (BE) gives dimethylbenchrotrenes [xylene-Cr(CO)₃,7] which are also formed by refluxing pureBE with Cr(CO)₆—although with much lower yields. Similarily, from di-n-pentylether and Cr(CO)₆ isobutyl- and 1-methyl-3-propyl-benchrotrene (13 and14) were obtained, whilst from di-n-propyl- and-hexylether, resp., and Cr(CO)₆ no benchrotrenes could be isolated.Tentative assumptions on the catalytic action of certain functional groups were confirmed by the reaction ofBE and Cr(CO)₆ in the presence of carbonamides, such as acetamide, urea and pyrrolidone, where 1,4-dimethylbenchrotrene (7 c) was formed with appreciable yields.Studies using dideuteratedBE showed that—at least for the reaction of9 with Cr(CO)₆ (giving a much lower yield of7 than with undeuteratedBE)—a simple bimolecular mechanism can be excluded.

     

Porous Solids of Divalent Metal Complexes Assembled Through Hydrogen Bonding and π–π Stacking Interactions

The compound N, N-di(6-methyl-2-pyridyl)formamidine (HDMepyF) has been exploited in preparation of porous materials of divalent metal complexes of the formulae M(HDMepyF)₂(NO₃)₂ (M=Cd, 1; Co, 2; Ni, 3) and M(HDMepyF)₂X₂ (M=Mn, X=Cl, 4; M=Mn, X=Br, 5; M=Ni, X=Cl, 6; M=Ni, X=Br, 7). Their structures have been determined by X-ray crystallography. Each metal center of these complexes is approximately octahedrally coordinated by four nitrogen and two halogen or oxygen donor atoms. Complexes 1– 5 and 7 self-assemble through similar hydrogen bonding motifs which involve the C–HsX (X=Cl, Br or O) hydrogen bondings and – stacking interactions between the HDMepyF ligand and the X atoms to form porous structures.     

Formation of closo-rhodacarboranes containing η2,η3-(CH2=CHC5H6) ligand in the reaction of μ-dichloro-bis[(η4-norbornadiene)rhodium] with nido-dicarbaundecaborates [K][nido-7-R1-8-R2-7,8-C2B9H10]

The reactions of a complex [(⁴-C₇H₈)RhCl]₂ (C₇H₈ is norbornadiene) with salts of substituted nido-dicarbaundecaborates, [K][nido-7-R¹-8-R²-7,8-C₂B₉H₁₀] (R¹ = R² = H (a); R¹ = R² = Me (b); R¹, R² = 1,2-(CH₂)₂C₆H₄ (c); R¹ = Me, R² = Ph (d)), in CH₂Cl₂ afforded new closo-(²,³-(4-vinylcyclopenten-3-yl))rhodacarboranes. The structures of the compounds were studied by multinuclear NMR spectroscopy. A probable mechanism of the rearrangement of the norbornadiene ligand is discussed.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1875–1878, September, 2004.     

An infrared and raman spectroscopic investigation of copper(II) tetracyanonickelate complexes ofα-,β- andγ-picoline

Copper(II) dipicoline tetracyanonickelate complexes, CuL₂Ni(CN)₄ (L=,- or-picoline), have been prepared for the first time and their infrared and Raman spectra are reported. Their structure consists of polymeric layers of {Cu-Ni(CN)₄} with picoline molecules bound directly to the copper. It is proposed that the Cu-NC bonds are in two nonequivalent pairs in trans positions. Low temperature (83K) IR spectra have also been recorded and it is noted that the Ni(CN)₄ group frequencies increase with decreasing temperature while the picoline frequencies are insensitive to temperature.     

Synthesis of 5′-amino- and 5′-azido-2′,5′-dideoxy nucleosides from thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione

Summary Thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione (4) was silylated and condensed with methyl 5-azido-2,5-dideoxy-3-O-(4-methylbenzoyl)-D-erythro-pentofuranoside (2) in the presence ofTMS triflate to afford the corresponding protected nucleoside6 and acyclic nucleoside7. Deprotection of6 with MeONa/MeOH at room temperature gave 1-(5-azido-2,5-dideoxy--D-erythro-pentofuranosyl)-thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione (8) and the corresponding anomer9, whereas compound7 yielded 5-azido-2,5-dideoxy-1-(2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-1-yl)-1-O-methyl-D-erythro-pentitol (10) under the same reaction conditions. 1-(5-Amino-2,5-dideoxy--D-erythro-pentofuranosyl)thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione (11) was obtained on treating9 with Ph₃P in pyridine followed by hyrolysis with NH₄OH. The anomeric nucleosides14 and15 and the corresponding acyclic nucleoside16 were obtained when4 was trimethylsilylated and condensed with methyl 2-deoxy-3,5-di-O-(4-methylbenzoyl)-D-erythro-pentofuranoside (3) followed by deprotection with MeONa in MeOH. Compounds8 and9 were also obtained when the anomeric mixture14/15 was treated with a mixture of NaN₃, Ph₃P, and CBr₄ in dryDMF at room temperature.On leave from Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt     

Synthesis and Characterization of Tetraosmium Carbonyl Complexes Containing a Bridging CO2 Ligand

Treatment of (thd)H (thd=2,2,6,6-tetramethyl-3,5-heptandionate) with excess Os₃(CO)₁₂ in an autoclave at 180°C gives the formation of a brown metal chain complex [Os₂(CO)₅(thd)₂]₂ (1) and a yellow CO₂ cluster complex [Os₄(-H)(-CO₂)(thd)(CO)₁₃] (2) in low yields. Complex 2 was fully identified by a combination of spectroscopic methods and X-ray diffraction study, showing a unique CO₂ ligand bridging a triosmium metal fragment, Os₃(-H)(CO)₁₀ and a monometallic osmium fragment, Os(CO)₃(thd). Upon treatment of 1 with Me₃NO at an elevated temperature, oxidation of the CO ligand occurred at the position trans to the unique CO₂ ligand on the Os(CO)₃(thd) fragment, giving the formation of a second CO₂ cluster [Os₄(-H)(-CO₂)(thd)(CO)₁₂(NCMe)] (3), which is stabilized by a weakly coordinated acetonitrile molecule.     

Eine breit anwendbare Synthese fluoreszierender kondensierter α-Pyrone

In a two step procedure and in usually good yield an -pyrone ring can be annelated to (enolized) cyclic -dicarbonyl compounds like 4-hydroxy-2-pyrones, 4-hydroxycoumarins, 4-hydroxy-2-quinolones and more complex malonylheterocycles, but also to -naphthole.In a first step the combined action of triethyl orthoformate and arylamines upon the dicarbonyl system affords the anilinomethylene derivativesB in usually high yields.B is reacted with an active methylene nitrile (like alkyl cyano-acetates) and one equivalent of a strong base (like sodium methoxide or potassium hydroxide) in a polar aprotic solvent (like dimethylformamide). Subsequent acidification with dilute aqueous acid gives the corresponding -pyroneD with yields from 18 to 84%.The reaction sequence is broadly applicable, which is demonstrated by the synthesis of a series of known (3, 7, 16, 31) and novel (10, 19, 22, 25, 28, 34) heterocyclic systems. Most of them exhibit strong fluorescence in the visible with emission maxima between 450 and 510 nm.

208. Mitt.:H. Wittmann undF. Günzl, Z. Naturforsch.33b, 1540 (1978).     

Exo-H- andendo-H-η4-pentamethylcyclopentadiene complexes of platinum

A mixture ofendo-H andexo-H isomers (1a and1b) of the (⁴-C₅Me₅H)PtCl₂ complex was prepared by the reaction of K₂PtCl₄ with C₅Me₅H in MeOH. The mixture of isomers reacts with CpTl in the presence of TiBF₄ to give a novel complex, [(⁴-C₅Me₅H)Pt(⁵-C₅H₅)]⁺BF₄ ^–, as a mixture ofendo-H- andexo-H-isomers (2a and2b). The data of¹H and¹³C NMR spectroscopy of the resulting complexes are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 514–517, March, 1994.     

Cubane-Type Molybdenum-Zinc or -Cadmium Mixed-Metal Clusters with Diethyldithiophosphate or Nitrilotriacetate Ligands

The reactions of sulfur-bridged clusters, [Mo₃( ₃-S)(-S)₃(-dtp)(dtp)₃(CH₃CN)] (1) in acetonitrile or [Mo₃( ₃-S)(-S)₃(Hnta)₃]^2– (2) in pure water, with zinc or cadmium metal result in the formation of three novel molybdenum-zinc or molybdenum-cadmium mixed-metal clusters, [Zn{( ₃-S)₄Mo₃(-dtp)(dtp)₃(CH₃CN)}₂] (3), [Cd{( ₃-S)₄Mo₃(-dtp)(dtp)₃(CH₃CN)}₂] (4), and [Cd{( ₃-S)₄Mo₃(Hnta)₃}₂]^4– (5), respectively. The X-ray crystal structures of 1·H₂O(1), 3, 4, and [Co(H₂O)₆]₂ 5·22H₂O (5) were determined, and the existence of the sandwich cubane-type cores Mo₃S₄MS₄Mo⁸⁺ ₃ cores (M=Zn, Cd) in 3, 4, and 5 verified. By the change of the ligands, the peak positions at the longest wavelength in the electronic spectra are distinctly different from each other between 4 (856 nm) and 6 (1235 nm). The electronic structures of 3, 4, and 5 have been calculated by Discrete Variational (DV)-X method.     

The polyiodide salts: Pyridinium pentaiodide;β-naphthylammonium pentaiodide; andN-methyl-γ-picolinium heptaiodide. Structures with channel inclusion features

The crystal structures of three polyiodode salts are reported (pyridinium pentaiodide, monoclinic,P2 ₁/m,a=9.221(5),b=12.918(5),c=6.026(4) Å, =103.60(7)^o,Z=2,R _F=0.087 for 1187 intensities; -naphthyl-ammonium pentaiodide, triclinic,173-1,a=10.390(5),b=9.502(5),c=4.462(3) Å, =99.19(7), =90.40(7),=108.49(8)^o,Z=2,R _F=0.059 for 1319 intensities;N-methyl--picolinium heptaiodide, monoclinic,C2/c,a=19.315(7),b=12.714(5),c=8.442(4) Å, =107.26(7)^o,Z=4,R _F=0.065 for 1336 intensities). All three structures can be described as having channel inclusion features; the cations are contained in channels in polyiodide frameworks based on different arrangements of I₂ molecules and I ₃ ^– anions. This structural type is the converse of the more widespread kind where polyiodide anions are contained in an organic matrix (e.g., cyclodextrin polyiodides). Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82016 (30 pages).Part X of Crystal Structures of Polyiodide Salts and Complexes. For Part IX, see F. H. Herbstein, G. M. Reisner, and W. Schwotzer,Acta Crystallogr. C, accepted for publication, 1984     

Transition Metal Halide Salts of 1,3-bis(4-Pyridyl)propane: Synthesis and Structural Characterization

The resulting salts of (H₂bpp)MX₄ · n H₂O (M = Zn, X = Cl, n = 1, 1; M = Cd, X = Br, n = 0, 2; M = Hg, X = Cl, n = 1, 3; M = Cu, X = Cl, n = 0, 4; M = Cu, X = Br, n = 1, 5; M = Pt, X = Cl, n = 1, 6) were crystallized from the reaction mixture prepared by adding MX₂ to the HX solution of 1,3-bis(4-pyridyl)propane (bpp), while the salt of colorless (H₂bpp)SnCl₆, 7, was crystallized from the reaction mixture prepared by adding SnCl₂ to the HCl solution of bpp. Their structures have been determined by X-ray crystallography. All the compounds show supramolecular structures in the solid state by intermolecular hydrogen bondings and aromatic – interactions. The H₂bpp²⁺ cations in these metal salts adopt the gauche–gauche and anti–anti conformations with different dihedral angles for the two pyridyl rings.     

Synthesis of the grapevine moth sex pheromone by Grignard—Schlosser cross-coupling: The effect of the electrophile structure on the stereoisomeric ratio in the reaction products

1-Acetoxy-2E,4Z-heptadiene (4) and 1-bromo-3E,5Z-octadiene (5) were obtained with 90 and 88–92 % configurational purity, respectively, starting from 2,4-heptadiyn-1-ol or 3,5-octadiyn-1-ol. The Li₂CuCl₄-catalyzed cross-coupling of the allylic acetate4 with 5tert-butoxypentylmagnesium chloride affords 1-tert-butoxy-7E,9Z-dodecadiene (11) contaminated with 25 % of minor stereoisomers in 54–60 % overall yield. Under similar conditions, the homoallylic bromide5 reacts with 4-tert-butoxybutylmagnesium chloride to give in 50–52 % yield another sample of diene11 containing 17 % of minor stereoisomers. If the latter coupling is carried out with enyne8 instead of5 followed bycis-hydrogenation of the triple bond in the resulting product, the configurational purity of diene11 is as high as 84.7 % (45 % overall yield). The reaction of11 with Ac₂O in the presence of FeCl₃ leads directly to the target 7E,9Z-dodecadienyl acetate (1) with somewhat lower configurational purity than that of the starting ether11.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1133–1137, June, 1993.     

Strukturelle Abwandlungen anN-Acetylneuraminsäure, 4. Mitt. Transformationen am Diethyl-dithioketal desN-Acetylneuraminsäure-γ-lactons

Partial protection of diethyldithioketal ofN-acetylneuraminic acid--lactone using one or two equivalents oft-butyldimethylchlorosilane leads to the 9-O-silyletherderivative7 and the 8,9-bis-O-silylderivative5, resp. The reaction of1 as well as7 with 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane (TIPSiCl₂) yields selectively the protected products4 and9. The 9,8,7,6-tetra-O-acetyl-N-acetylneuraminic acid--lactone derivative3 is formed by the oxidative desulfurazation of the peracteylated form of1 (i. e.2) by means ofNBS. By reaction of5 withTPPDEAD the 6,7-carbonato compound6 arises instead of the expected 6,7-epoxyderivative. The analogous carbonate8 is formed by treating7 with bisimidazolylcarbonate.

     

Synthesis and crystal structure ofN,N′-DicyclohexylpiperazineN,N′-dioxide octahydrate

N,N-DicyclohexylpiperazineN,N-dioxide octahydrate, C₁₆H₄₆N₂O₁₀,M _r=426.55, monoclinic, space groupC2/m (No. 12),a=12.961(4),b=11.533(4),c=7.907(1) Å, =98.37(2)^o,V=1169.3(6) ų,Z=2. The structure was solved by the direct method and refined toR=0.045 for 1192 observed MoK reflections. TheN,N-dioxide molecule occupies a site of symmetry 2/m. The piperazine ring takes the chair form with the two N–O bonds oriented axially in atrans configuration. Hydrogen bonding between the water molecules, as well as between theN-oxide groups and water molecules, gives rise to a puckered layer composed of edge-sharing four-membered, five-membered, six-membered, and eight-membered rings. Adjacent layers are cross-linked by theN,N-dicyclohexylpiperazine moieties lying between them, thereby generating a sandwich structure consolidated by covalent and hydrogen bonding. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82062 (8 pages).     

Synthesis of Co3(CO)7(μ-η3-Allyl)(μ3-X) Complexes (X=S, Se) and Structure of the Selenium Derivative

The complexes Co₃(CO)₉( ₃-X) (X=S, Se) can be reduced to the corresponding anionic species [Co₃(CO)₉( ₃-X)]^–, which react with allyl bromide to give Co₃(CO)₇(- ³-C₃H₅)( ₃-X) (X=S, Se). These are the first two cobalt complexes containing the bridging - ³-allyl ligand. The structure of the selenium complex was determined by X-ray crystallography. Crystal data for Co₃(CO)₇(- ³-C₃H₅)( ₃-Se) are as follows: space group P2₁/c, a=9.051(2) Å, b=8.102(2) Å, c=21.27(4) Å, =93.82(3)°, Z=4, and R=0.0565 for 2491 observed reflections.     

Transformed steroids

A preparative method for 9a-hydroxylation of ⁵-3-hydroxysteroids using the fungi ofCircinella sp. 10Kh-1220 not capable of modifying theA ring has been developed. It is established that the yields of the main and the side products greatly depend on the transformation conditions, mycelium age, and the structure of the steroid substrate. Under the optimal transformation conditions novel 9-hydroxysubstituted derivatives of androstenolone, pregnenolone, 16-dehydro-16,17-epoxy-, and-16-methoxypregnenolone have been obtained in 36–80 % yields.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 737–743, April, 1994.     

Stereoselective Synthesis of (1Z,3E)-2-Ethoxycarbonyl-Substituted 1,3-Dienes via Stille Coupling of (E)-α-Stannyl-α,β-Unsaturated Esters with Alkenyl Halides

Palladium-catalyzed hydrostannylation of alkynyl esters in benzene at room temperature gives stereoselectively (E)-α-stannyl-α,β-unsaturated esters 1 in good yields. (E)-α-Stannyl-α,β-unsaturated esters 1 are difunctional group reagents that undergo Stille coupling reactions with alkenyl halides 2 in the presence of Pd(PPh₃)₄ and CuI co-catalyst to afford stereoselectively (1Z,3E)-2-ethoxycarbonyl-substituted 1,3-dienes 3 in good yields.     

Ein einfacher Weg zu α-substituierten (E)-3-Oxo-1-alkenylphosphonsäureestern

Zusammenfassung -Substituierte -Acylvinylphosphonate3 mitE-Konfiguration [R ²CO-CH=C(R ¹)-P(O)(OR)₂], werden in guten Ausbeuten durchWittig-Reaktion von Acylphosphonsäureestern1 [R ¹CO-P(O)(OR)₂,R ¹=Alkyl oder Aryl] mit (2-Oxoalkyliden)triphenylphosphoranen2 [R ²CO-CH=PPh ₃,R ²=Alkyl, O-Alkyl oder CH₂ X (X=Br, OMe, CO₂ Et)] erhalten.

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A convenient route to -substituted dialkyl (E)-3-oxo-1-alkenylphosphonates

-Substituted dialkyl (E)--acylvinylphosphonates [R ²CO-CH=C(R ¹)-P(O)(OR)₂,3], are easily obtained in good yields byWittig-reaction of dialkyl acylphosphonates1 [R ¹CO-P(O)(OR)₂,R ¹=alkyl or aryl) with 2-oxoalkylidene triphenylphosphoranes2 [R ²CO-CH=PPh ₃,R ²=alkyl, O-alkyl and CH₂ X (X=Br, OMe, CO₂ Et)].

     

Convergent synthesis of 2′,3′-dideoxy-3′-mercapto nucleosides — Potential anti-HIV agents

Summary Methyl 3-benzoylthio-5-O-tert-butyldiphenylsilyl-2,3-dideoxy--D-erythro-pentofuranoside (4) and its corresponding anomer5 were synthesized in four steps from 2-deoxy-D-ribose and used as substrates for the synthesis of nucleosides by condensation with silylated thymidine and N⁶-isobutyryladenine. The nucleosides were deprotected by treatment with Bu₄NF inTHF followed by reaction with MeONa in MeOH to give 3-deoxy-3-mercaptothymidine (8), 2,3-dideoxy-3-mercaptoadenosine (15) and its corresponding anomer16. In the latter reactions it was important to use degassed solvents to minimize formation of the corresponding disulfides of purine nucleosides. Using Bu₄NF, without subsequent reaction with MeONa in the deprotection reaction, resulted in intermolecular transesterification reactions.On leave from Chemistry Department, Faculties of Science and Education, Tanta University, Tanta, Egypt     

New class of neutral paramagnetic binuclear sulfur-containing iron nitrosyl complexes

Neutral paramagnetic binuclear iron nitrosyl complexes, whose structures and properties differ from those of the known Roussin"s red salt esters, were synthesized for the first time. The iron nitrosyl complexes [Fe₂(₂-SR)₂(NO)₄]·nH₂O (¹-S, ¹-N; n = 1 or 2; R is 5-amino-1,2,4-triazol-3-yl (1), 1,2,4-triazol-3-yl (2), 1-methyltetrazol-5-yl (3), or benzothiazol-2-yl (4)) were prepared by the exchange reactions of Na₂Fe₂(S₂O₃)₂(NO)₄ with heterocyclic thiols. According to the results of X-ray diffraction analysis, complex 1 has a centrosymmetrical dimeric structure in which the iron atoms are linked through the -N—C—S structural fragment. Each Fe atom is bound to the N atom of one ligand and the S atom of another ligand. The isomer shifts of complexes 1—4 have virtually equal values (_Fe = 0.291(1)—0.304(1) mm s^–1 at T = 85 K), which are twice as large as _Fe for Roussin"s red salt esters. The iron atoms in complexes 1—4 have the low-spin configuration d⁷ (Fe⁺). The ESR spectra of polycrystalline powders of complexes 1—4 consist of a single Lorentzian line with g = 2.032 and a width of 6—10 mT. The temperature dependence of the magnetic susceptibility of complex 1 in the temperature range of 80—300 K is adequately described by the Curie—Weiss law with 8 K; the effective magnetic moment per iron atom is 1.85 B.