Protonation of a series of diphosphazane- and diphosphine-bridged derivatives of iron and ruthenium: dependence of the nature of the hydride ligand on the metal and the bridging diphosphorus ligand

Protonation of the dinuclear compounds [M₂(μ-CO)(CO)₄(μ-R₂PYPR₂)₂] by HBF₄ or HPF₆ leads to the formation of crystalline cationic hydrido products [M₂H(CO)₅(μ-R₂PYPR₂)₂]X and [M₂(μ-H)(μ-CO)(CO)₄(μ-R₂PYPR₂)₂]X (X = BF₄ or PF₆) in which the hydride ligand is terminal for M = Ru, Y = N(Et) and R = OMe or OPrⁱ and bridging for M = Fe, Y = CH₂ and R = Me or Ph, for M = Fe, Y = N(Et) and R = OMe, OEt, OPrⁱ or OPh and for M = Ru, Y = CH₂ and R = Ph; the fluxional behaviour of [Ru₂H(CO)₅{μ-(RO)₂PN(Et)P(OR)₂}₂]⁺ (R = Me or Prⁱ) in solution is described.     

Protonated forms of 2-(2-furyl)pyrroles and their interconversions

It was shown by ¹H NMR spectroscopy that 2-(5-R¹-2-furyl)-3-R²-1-R¹-pyrroles (R¹= H, Me; R²=H, Me; R³=H, Et, CH=CH₂) are protonated by acids (HSO₃F, HCO₂CF₃, HCl, HBr) either at the C(₅) atom of the pyrrole ring or at the C(₅) atom of the furan ring, depending on the conditions. The energies of formation (H), the charges, and the partial electron densities of the boundary orbitals of 2-(2-furyl)pyrrole (I) and its protonated forms (IA and IB) were calculated by the MNDO method. The calculated H values for the IA and IB forms are in agreement with their experimental ratio. According to the calculated reactivity indexes, the protonation of pyrrole is subject to orbital control and may include the prior formation of less stable protonated forms.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1343–1355, October, 1989.     

Synthèse de molécules organométalliques possédant un manganèse chiral

Synthesis of diastereoisomeric manganese complexes is described, starting from LMn(CO)₃, carbonyl substitutions gave LMn(CO)(PPh₃)[P(OMe)₃] (L = h⁵-C₅H₃, 1-CO₂Me, 3-Me).     

Stereochemical specificity of the palladium-catalyzed hydrogenation of cyclohexa[b]thiopyrans and their derivatives

Conformationally and configurationally homogeneous 2-R¹-4-R²-cis-1-thiadecalins with an equatorial orientation of the substituents attached to the C(₂) and C(₄) atoms were isolated as the final reduction products in the catalytic hydrogenation on palladium of 2-R¹-4-R²-4H(6H)-cyclohexa[b]thiopyrans, cis-3-R¹-5-R²-2-thiabicyclo[4.4.0]-^1,6-decenes, and 2-R¹-4-R²-cyclohexa[b]thiopyrylium tetrafluoroborates and trifluoroacetates. cis-3-R¹-5-R²-2-Thiabicyclo[4.4.0]-^1,6-decenes were obtained as intermediates in the incomplete reduction of 2-phenyl- and 2,4-diphenyl-4H-cyclohexa[b]thiopyrans and 2-(4-methoxyphenyl)-4-R²-cyclohexa[b]thiopyrylium salts; 2-R¹-4-R²-6H-cyclohexa[b]thiopyrans undergo complete reduction of the double bonds of the heteroring. The hydrogenation products were oxidized to sulfoxides and sulfones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 614–619, May, 1987.     

Synthesis of New 5-Mercapto-1,3-oxazole Derivatives on the Basis of 2-Acylamino-3,3-dichloroacrylonitriles and Their Analogs

Enamides of the general formula Cl₂CÍC(X)NHCOR¹, where X = CN, COOAlk, CONH₂, P(O)(OEt)₂, P(O)Ph₂, +PPh₃ Cl^-, were treated in succession with alkane- or arenethiols and silver carbonate to obtain 5-alkyl(aryl)thio-2-R¹-4-X-1,3-oxazoles with high selectivity. The latter were converted into the corresponding sulfonyl derivatives. Unlike 2-acylamino-3,3-dichloroacrylonitriles which react with sodium hydrogen sulfide in a nonselective fashion, reactions of derivatives like Cl(ArS)CÍC(CN)NHCOR¹ with NaHS lead to hitherto unknown 5-arylthio-4-thiocarbamoyl-2-R¹-1,3-oxazoles whose structure was confirmed both by spectral methods and by cyclocondensation with bromoacetophenone according to Hantzsch. Heating of some 2-aryl-5-mercapto-4-X-1,3-oxazoles with benzenethiols results in recyclization into the corresponding 2,4-disubstituted 5-arylthio-1,3-thiazoles, presumably due to prototropic tautomerism in the 5-mercaptooxazole fragment.     

Synthesis and reactions of phosphido-bridged μ3-alkylidyne clusters; X-ray crystal structures of the complexes [Co2W(μ-PEt2)3(CO)5(η-C5H5)], [Co2W{μ3-C(R)C(Et)C(Et)C(O)}(μ-CO)(CO)4(PPh2{C(Et)CHEt})(η-C5H5)], and [CoW{μ-C(R)C(Et)C(Et)C(OH)}(CO)4(η-C5H5)] (R = C6H4Me-4)

Reactions of the phosphido-bridged complexes [Co₂W(μ-H)(μ₃-CC₆H₄Me-4)(μ-PR₂)(CO)₆(η-C₅H₅)] (R = Ph or Et) with PR₂H (R = Ph or Et) or RCCR (R = Me or Et) are dominated by processes involving facile PC, CC and CH bond formation. The X-ray structures of the complexes [Co₂W(μ-PEt₂)₃(CO)₅(η-C₅H₅)], [Co₂W{μ₃-C(R)C(Et)C(Et)C(O)}(μ-CO)(CO)₄(PPh₂{C(Et)CHEt})(η-C₅H₅)], and [CoW{μ-C(R)C(Et)C(Et)C(OH)}(CO)₄(η-C₅H₅)] (R = C₆H₄Me-4) have been determined.     

Oxidation of aromatic compounds: XV. Oxidation of arylacetylenes in a system HF-PbO<Subscript>2</Subscript>

The oxidation of symmetrically substituted diarylacetylenes ArC≡CAr (Ar=C₆H₄R) containing strong electron-withdrawing groups R = 4-COMe, 4-CO₂Me, 3-CO₂Et, and 4-NO₂ in a system HF-PbO₂ at ?10÷?20°C led within 0.5–3 h to the formation of Z,Z-1,2,3,4-tetrakis(aryl)-1,4-difluorobuta-1,3-dienes ArFC=C(Ar)?(Ar)C=CFAr. The butadiene structures obtained exist in solutions as s-cis-and s-trans-conformers and in the crystalline state are present in the stable s-cis-form.     

2-Azido-1,3,4-thiadiazoles, 2-Azido-1,3-thiazoles,and Aryl Azides in the Synthesis of 1,2,3-Triazole-4-carboxylic Acids and Their Derivatives

Diazotization of 2-amino-1,3,4-thiadiazoles gave 1,3,4-thiadiazole-2-diazonium sulfates which were converted to 2-azido-1,3,4-thiadiazoles. The latter reacted with ethyl acetoacetate in the presence of sodium methoxide in methanol to produce 1-(5-R¹-1,3,4-thiadiazol-2-yl)-5-R²-1H-1,2,3-triazole-4-carboxylic acid derivatives. The reactions of 2-azido-5-methyl-1,3,4-thiadiazole and 2-azido-1,3-thiazole with ethyl 3-(1,3-benzodioxol-5-yl)-3-oxopropanoate led to the formation of 1,2,3-triazole ring under milder conditions (K₂CO₃, DMSO). Various 1,2,3-triazole-4-carboxylic acid derivatives were synthesized.     

Aminorhenium carbon dioxide complexes: formal oxidation of a carbon monoxide ligand with peroxy-acids or bromine/hydroxide

The electron-rich aminorhenium complexes η⁵:η¹-C₅H₄CH₂CH₂NR(CH₃)Re(CO)₂ (3a-d; R=methyl, benzyl, n-butyl, n-butyl-OH) are easily oxidized with peroxy-acids to give the corresponding η²-CO₂ complexes η⁵: η¹- C₅H₄CH₂CH₂NR(CH₃)Re(CO)(η²-CO₂) (4a-d) in excellent yield. The resultant η²-CO₂ complex is predominantly the anti-isomer. The structures of η²-CO₂ complex η⁵:η¹-C₅H₄CH₂CH₂N(CH₃)(n- C₄H₈OH)Re(CO)(η²-CO₂) (4d-anti) and the corresponding CO complex 3d have been confirmed by X-ray crystallography. The η²-CO₂ complexes 4a-4d are stable at ambient temperature under air. In addition to peroxy-acid oxidation, bromination of the aminorhenium dicarbonyl complexes followed by base treatment also provided the corresponding η²-CO₂ complexes. The reaction mechanism for the formation of CO₂ complex from the corresponding dicarbonyl is discussed briefly.     

STEREOSELECTIVE SYNTHESIS OF MONOFLUORO-OLEFINS FROM DIISOPROPYL (CARBOETHOXYFLUORO-METHYL)PHOSPHONATE

Abstract

Treatment of ethyl oxalyl chloride or methyl oxalyl chloride with lithium diisopropyl(carboethoxyfluoromethyl)phosphonate[(i-PrO)₂P(O)CFCO₂Et]^?Li⁺ 2 followed by in siru nucle-ophilic addition with methylmagnesium iodide or vinyl magnesium bromide affords with exclusive E-stereoselectivity formation of diethyl-2-fluoro-3-methyl fumarate (CH₃)(C0₂Et)C[dbnd]CFCO₂Et 4 or 75% of the E-isomer of a-fluoro-P-vinyl-a,P-unsaturated diester (E,Z)-(CH₂[dbnd]CH)(CO₂C₂H₅)C[dbnd]CFCO₂Et 5, respectively. However, direct reaction of ethyl pyruvate with 2 gives the fluoro-olefin (CH₃)(CO₂Et)C[dbnd]CFCO₂Et 4 with 79% E-stere-oselectivity. The E/Zratio of (CH₂[dbnd]CH)(CO₂Et)C[dbnd]CFCO₂Et 5 depends on the HMFT or DMPU cosolvents present in the reaction mixture.     

Stabilization of a Silaaldehyde by its η2 Coordination to Tungsten

Treatment of pyridine‐stabilized silylene complexes [(η⁵‐C₅Me₄R)(CO)₂(H)W?SiH(py)(Tsi)] (R=Me, Et; py=pyridine; Tsi=C(SiMe₃)₃) with an N‐heterocyclic carbene ^MeIⁱPr (1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene) caused deprotonation to afford anionic silylene complexes [(η⁵‐C₅Me₄R)(CO)₂W?SiH(Tsi)][H^MeIⁱPr] (R=Me ( 1‐Me ); R=Et ( 1‐Et )). Subsequent oxidation of 1‐Me and 1‐Et with pyridine‐N‐oxide (1 equiv) gave anionic η²‐silaaldehydetungsten complexes [(η⁵‐C₅Me₄R)(CO)₂W{η²‐O?SiH(Tsi)}][H^MeIⁱPr] (R=Me ( 2‐Me ); R=Et ( 2‐Et )). The formation of an unprecedented W‐Si‐O three‐membered ring was confirmed by X‐ray crystal structure analysis.     

New one-pot, efficient, and regioselective method for the synthesis of 3-Trifluoromethyl-1H-1-phenylpyrazoles and alkyl 3-carboxylate analogs

An efficient and regioselective procedure for the synthesis of a series of alkyl(aryl/heteroaryl) substituted 3-trifluoromethyl-1H-1-phenylpyrazoles and alkyl 3-carboxylate analogs, from the cyclocondensation reactions of 4-alkoxy-1,1,1-trihaloalk-3-en-2-ones [CX₃C(O)CR²=CR¹(OMe/OEt), where R¹ = H, Me, Ph, 2-Furyl; R² = H; R¹-R² = -C₄H₈- and X = F, Cl] and 1-phenylsemicarbazide in an acidified alcoholic medium (R³OH/H₂SO₄), where R³ = Me, Et, Prⁱ was successfully applied and is described here in detail.     

Substitution of Secondary Benzylic Phosphates with Diarylmethyl Anions

Substitution of diethyl and diphenyl benzylic phosphates, Alk-CH(Ar¹)OP(O)(OR)₂ (R = Et, Ph; Alk = Me, Et, i-Pr; Ar¹ = aryl), with the anions derived from Ar²CH₂ (Ph₂CH₂,9H-xanthene and fluorene) and n-BuLi at –15 °C was studied. For phosphates with Me as an Alk, diethyl phosphates produced Me-CH(Ar¹)CH(Ar²)₂ (Ar¹ = 4-halo-, 4-CN, 4-Me-, 2-Me, 2-Br-, 3-MeO-phenyl and 2-naphthyl). However, an unwanted substitution at the Et group competed with phosphates of Alk = Et- and i-Pr. Fortunately, the corresponding diphenyl phosphates cleanly underwent the desired substitution. Two enantioenriched phosphates, MeCH(Ph)OP(O)(OEt)₂ and EtCH(Ph)OP(O)(OPh)₂, proceeded with complete inversion of the stereochemistry.     

Stabilisation of [Fe2(CO)9] and [Ru2(CO)9] bu substitution with bridging diphosphorus ligands

Reaction of [Fe₂(CO)₉] with a half molar amount of R₂PYPR₂ (Y = CH₂, R = Ph, Me, OMe or OPrⁱ; Y = N(Et), R = OPh, OMe or OCH₂; Y = N(Me), R = OPrⁱ or OEt) leads to the ready formation of a product which on irradiation with ultraviolet light rapidly decarbonylates to the heptacarbonyl derivative [Fe₂(μ-CO)(CO)₆{μ-R₂PYPR₂}]. Treatment of the latter with a slight excess of the appropriate ligand results, under photochemical conditions, in the formation of the dinuclear pentacarbonyl complex [Fe₂(μ-CO)(C))₄{μ-R₂PYPR₂}₂] but under thermal conditions in the formation of the mononuclear species [Fe(CO)₃{R₂PYPR₂}]. Reaction of [Ru₃(CO)₁₂] with an equimolar amount of (RO)₂PN(R′)P(OR)₂ (R′ = Me, R = Prⁱ or Et; R′ = Et, R = Ph or Me) under either thermal or photochemical conditions produces [Ru₃(CO)₁₀{μ-(RO)₂PN(OR)₂}] which reacts further with excess (RO)₂PN(R′)P(OR)₂ on irradiation with ultraviolet light to afford the dinuclear compound [Ru₂(μ-CO)(CO₄{μ-(RO)₂PN(R′)P(OR)₂}₂]. The molecular structure of [Ru₂(μ-CO)(CO)₄{μ-(MeO)₂PN(Et)P(OMe)₂}₂], which has been determined by X-ray crystallography, is described.     

Reaction of 3-oxo-3-R<Superscript>1</Superscript>-<Emphasis Type="Italic">N</Emphasis>-R<Superscript>2</Superscript>-propanethioamides with 2-amino-5-R-pyridines

Direction of a reaction between 3-oxo-3-R¹-N-R²-propanethioamides and 2-amino-5-R-pyridines in acetic acid depends on the structure of initial thioamides: at R¹ = Me, R² = Ar, Et 2-methyl-7-R-4H-pyrido[1,2-a]-pyrimidine-4-thiones are obtained, and at R¹ = Ar, R² = Me form 1-methyl-5-(N-methylaminothiocarbonyl)-4,6-diaryl-1,2-dihydropyridine-2-thiones.     

Insertion of SnCl2 into Pt–Cl bonds: synthesis and characterization of four- and five-coordinate trichlorostannylplatinum(II) complexes

Reaction of platinum(IV) chloride with SnCl₂?·?2H₂O in the presence of [NHR₃]₃Cl (R?=?Me, Et) in 3M hydrochloric acid affords the anionic five-coordinate platinum(II) complexes [NHR₃]₃[Pt(SnCl₃)₅], R?=?Me (1), Et (2), respectively. Moreover, platinum(IV) chloride reacts with SnCl₂?·?2H₂O in the presence of bis(triphenylphosphoranylidene)ammonium chloride in acetone/dichloromethane to form [N(PPh₃)₂]₃[Pt(SnCl₃)₅] (3). In contrast, reaction of an acetone solution of platinum(IV) chloride with SnCl₂?·?2H₂O in the presence of bis(triphenylphosphoranylidene) ammonium chloride resulted in the formation of cis-[N(PPh₃)₂]₂[PtCl₂(SnCl₃)₂] (4). The same products are obtained by using a platinum(II) salt as starting material. Similarly, cis and trans- dichlorobis(diethyl sulfide)platinum(II) reacts with SnCl₂?·?2H₂O in 5M hydrochloric acid to give [PtCl(SEt₂)₃]₃[Pt(SnCl₃)₅] (5) by facile insertion of SnCl₂ into the Pt–Cl bond. However, treatment of an acetone solution of cis- and trans-[PtCl₂(SEt₂)₂] with SnCl₂?·?2H₂O in the presence of a small amount of HCl resulted in the formation of 5, which dissociates in solution to give [PtCl₂(SEt₂)₂]. The complexes have been fully characterized by elemental analysis and multinuclear NMR (¹H,?¹³C,?¹⁹⁵Pt,?¹¹⁹Sn) spectroscopy. A structure determination of crystals grown from a solution of 2 by X-ray diffraction methods shows that platinum adopts a regular trigonal bipyramidal geometry.     

Insertion Reactions of Carbon Disulfide into Mg‐C and Mg‐N Bonds: Syntheses and Structural Determinations of Mg(S2CY)2(THF)n(Y=NEt2, NiPr2, iPr,Ph) and BrMg(S2CZ)(THF)3(Z=Ph,iPr)

The insertion reaction of CS₂ with Mg(NR₂)₂ (R= Et, ⁱPr), MgR′₂ (R′= Et, Ph) and R″MgBr (R″= ⁱPr, Ph) respectively lead solid products, Mg(S₂CNR₂)₂(THF)_n ( 1 : R= Et, n=2; 2 : R= ⁱPr, n=1), Mg(S₂C′R)₂(THF)₂ ( 3 : ′R= Et, 4 : ′R= Ph), BrMg(S₂C″R) (THF)₃ ( 5 : ″R= ⁱPr, 6 : ″R= Ph) in which the inserted carbon disulfides act as terminal chelating ligands. These compounds were characterized with ¹H, ¹³C NMR, IR spectroscopy, mass spectrometry, elemental analyses, and X‐ray crystallography.     

Heterylation of 3-R1-5-R2-1,2,4-Triazoles with Derivatives of 3,5-Dinitro-1,2,4-Triazole

Heterylation of 3-R¹-5-R²-1'2'4-triazoles (pK _a 3-12) with N-alkyl-, N-alkenyl-, N-alkoxy-carbonyl-, N-oxoalkyl-, N-nitroxyalkyl, N-nitroaminoalkyl-3'5-dinitro-1'2'4-triazoles results insubstitution of a nitro group in 5 position of the dinitro compound yielding 1-R-methyl-3-nitro-5-(3-R¹-5-R²-1,2,4-triazolyl)-1,2,4-triazoles. The side processes: Hydroxide-ion attack on C⁵ and (or) N¹ of the ring both in the substrate and in the target compound afford 1-R-methyl3-nitro-1,2,4-triazol-5-ones, 3,5-dinitro-1,2,4-triazole and NH-acids of N-C-bitriazole series. Optimal reaction media are aprotic dipolar substances, and for compounds prone to heterolysis ethyl acetate-water systems. The azole pK _a is the decisive factor controlling the composition and the ratio of reaction products. The process is promising for azoles with pK _a > 5, and the optimal range of pK _a is 8-10.     

Zur Thermodynamik der Metallcarbonate. 4. Mitteilung. Potentiometrische Untersuchungen am System Mn2+?CO2?H2O

The solubility and the complex equilibria in the system Mn²⁺-CO₂-H₂O have been investigated at 25°C in solutions of the constant ionic strength 3 M (Na)ClO₄. From experimental data the following values for equilibrium constants and Gibbs free energies of formation are deduced: A predominance area diagram for the system Mn²⁺-H₂-CO_2(g)-H₂S_(g) including MnCO_3(ppt.), α-MnS and Mn²⁺ is given.     

Features of the reaction of unsymmetrical 2-mercapto-imidazoles with aromatic and aliphatic ketones

The cyclization of unsymmetrical 2-mercaptoimidazoles with aliphatic and aromatic ketones has been studied. Using ¹H NMR and X-ray analysis it has been shown that 4-R¹-1H-2-mercaptoimidazoles undergo selective oxidative cyclization to the corresponding 3-R³-2-R²-6-R¹-imidazo[2,1-b][1,3]thiazoles while 6-R⁴-1H-2-mercaptobenzo[d]imidazoles give a mixture of 6-R⁴-3-R²-2-R³-benzo[4,5]imidazo[2,1-b][1,3]thiazole and 7-R⁴-3-R²-2-R₃-benzo[4,5]imidazo[2,1-b][1,3]thiazole in the ratio 1: 1. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 115–122, January, 2007.