Verbindungen des Germaniums und Zinns. 3. Sterisch überladene Alkylarylstannane durch Übertragung und Isomerisierung von 2,4,6-Tri-tert-butylphenylgruppen

Compounds of Germanium and Tin. 3. Sterically Congested Alkylarylstannanes by Transfer and Isomerization of 2,4,6-Tri-tert-butylphenyl Groups Reaction of SnBr₄ and SnI₄ with 2,4,6-tri-tert-butylphenyllithium (ArLi) by rearrangement of two Ar-groups gives the stannanes ArR₂SnBr ( 3 ) and ArR₂SnI ( 4 ), R = 2-methyl-2(3,5-di-tert-butylphenyl)propyl, which by a further transalkylation reaction with methyl lithium yield ArR₂SnCH₃ ( 5 ). However, treatment of 3 and 4 with tert-butyl lithium exclusively leads to ArR₂SnH ( 6 ) which surprisingly is also obtained by reaction of ArRSnCl₂ with tert-butyl lithium, presumably by an intermolecular R-group transfer. The structures of 5 and 6 were confirmed by X-ray crystallography.     

Structure and reactivity of xanthocorrinoids. Part V. Formation of trans-diol derivatives of 5,6-dihydrocobyrinic acid from xanthocorrinoids under acidic conditions

On treatment with H₂SO₄/MeOH, epimerization of hexamethyl cis-5,6-dihydroxycobyrinate c,8-lactam ( 3 ) takes place quantitatively at C(6), yielding the corresponding trans-diol 4 . The corresponding lactone 7 , whose structure has been established by X-ray analysis, is obtained from xanthocorrinoids 5 and 6 under similar conditions.     

Quinone chemistry. Synthesis and tautomerism of 4,7-indazolequinones

The reaction of 1 with hydrazines provided hydrazinium-4,7-dioxo-4,7-dihydroindazol-3-olates 2a-e and 4,7-indazolequinones 3f,g depending upon the nature of the substituent present in the reactants. Compounds 3a-g were obtained by treatment of 2a-e with sodium hydroxide. Fixed tautomers 4a-b and 5c-f were synthesized by methylation of the corresponding 3a-f or 2a-2e with diazomethane. Migration of a methyl group of 5c-f from the oxygen at C₃ to N₁ on heating afforded 6c-f . The tautomerism of 2a-e and 3a-g has been studied by comparing ir, uv, ¹H nmr and ¹³C nmr spectra with those of the fixed tautomers.     

Imination of N-methylpyridinium salts by liquid ammonia-potassium permanganate. A new synthesis of nudiflorine

Reaction of substituted 1-methyl(benzyl)pyridinium salts ( 1 ) with liquid ammonia/potassium permanganate leads to introduction of the imino group at the carbon adjacent to the nitrogen. The regiospecificity of the reaction strongly depends on substituent X: at C-6 for X = H, CONH₂, C₆H₅ and at C-2 for X = CH₃. 3-Aminocarbonyl-1-t-butylpyridinium iodide ( 5 ) on treatment with liquid ammonia/potassium permanganate exclusively gives the 4-imino compound 8 ; ¹H nmr spectroscopy shows that 5 in liquid ammonia gives a mixture of the σ-adducts 4-amino-1,4-dihydro- and 6-amino-1,6-dihydro-3-pyridinecarbonamide ( 6 and 7 ). Surprisingly, an oxodemethylation reaction is observed on treatment of 3-aminocarbonyl-1,6-dimethylpyridinium iodide ( 13 ) with liquid ammonia/potassium permanganate, 1,6-dihydro-1-methyl-6-oxo-3-pyridinecarboxamide ( 14 ) being obtained. This compound can easily be converted by phosphorus oxychloride into the alkaloid nudiflorine ( 15 ).     

Supermesityl-stabilisierte Iminoborane. III

Supermesityl stabilized Iminoboranes. III New Iminoboranes R? B?N? R′ (R = 2,4,6(t-Bu)₃C₆H₂), IIa – IIf , were obtained by base-induced HF-elimination from RBF? NHR′ ( Ia-Ie ) or directly from RBF₂ and lithiated H₂NR′ (for IIf ). Compounds II exhibit a differentiated behaviour upon thermal treatment depending on R′. While IIa (R′ = H) immediately reacts to give the corresponding benzo[1]borolane IIIa , the dimeric diazadiboretidine is formed from IIb (R′ = Me) at 100°C; IIc (R = Et) and IId (R = C₆H₅) deliver the benzo[1]borolanes IIIc and IIId when they are heated to 180°C (in melt). IIe (R = 2,6(i-Pr)C₆H₃) and IIf (R = adamantyl) are stable at 250°C. All compounds were characterized by elemental analyses and spectroscopically (MS, IR, NMR: ¹H, ¹³C, ¹¹B, ¹⁹F and in part ¹⁵N).     

Azidiniumsalze. 7. Mitteilung [1]. Synthese von 1-Äthyl-2-azido-6-X-chinolinium-fluoroboraten

6-X-Quinolines (X = CH₃, C₆H₅, CO₂C₂H₅, Cl, Br) are successively transformed into 1-methyl-6-X-carbostyrils, 2-chloro-6-X-quinolines and 1-ethyl-2-chloro-6-X-quinolinium-tetrafluoroborates; the latter are transformed into the title compounds by reaction with sodium azide in methanol. 2-Chloro-6-acetamido-quinoline is alkylated at two positions: at the nitrogen atom of the heterocyclic ring and obviously at the oxygen atom of the 6-substituent; with sodium azide in methanol the product of alkylation yields 1-ethyl-2-azido-6-amino-quinolinium-tetrafluoroborate. 1-Ethyl-2-azido-6-nitro-quinolinium-tetrafluoroborate is obtained by treating 1-ethyl-2-hydrazino-6-nitro-quinolinium-chloride with sodium tetrafluoroborate and sodium nitrite in diluted hydrochloric acid.     

Über Phosphorstickstoffverbindungen. XXXIII. Reaktionen von Diphenyltrichlorphosphoran mit Hydraziniumsalzen und -derivaten

Hydrazinium monochloride disproportionates on interaction with diphenyl-trichlorophosphorane, giving N₂ and [(C₆H₅)₂P(Cl)? N? PCl(C₆H₅)₂]Cl. The phosphinazine dihydrochloride [(C₆H₅)₂PCl? NH? NH? PCl(C₆H₅)₂]Cl₂ is obtained according to equation (4). The preparation of the P? N five-ring compound X, formulated in ?Inhaltsübersicht”?, is described.     

Colloidal catalysts based on iron(III) oxides. 1. Decomposition of hydrogen peroxide

The catalytic activity of a colloidal catalyst based on iron(III) oxides in decomposition of H₂O₂ is studied. The catalyst is obtained by hydrolysis followed by peptization of FeCl₃ · 6H₂O salt in water in the presence of 1% ethanol. The structure, composition, and size of colloidal particles of the catalyst are studied by the methods of Mössbauer spectroscopy, X-ray fluorescence, X-ray diffraction, and transmission electron microscopy. The obtained catalyst is based on α-Fe₂O₃ crystals with an admixture of other crystalline structures of iron oxides and carbon-containing compounds. The activity of the catalyst with respect to H₂O₂ decomposition undergoes nonlinear and nonmonotonic variations and its particle size enlarges beginning from 1 to 3 nm with increasing initial concentration of FeCl₃ · 6H₂O. The catalyst obtained under optimal conditions exhibits high activity corresponding to the most efficient agents of H₂O₂ decomposition.     

(2,4,6-Tri-tert-butylphenylimino)thioxo-and -selenoxophosphoranes. Synthesis and structural characterization

A series of stable imino(chalcogeno)phosphoranes R  P( X)  NAr, RPh, 2, 4, 6-Me₃C₆H₂, 2, 4, 6-i-Pr₃C₆H₂; Ar 2, 4, 6-t-Bu₃C₆H₂; X  S, Se ( 5bd, 6b,c ), has been prepared by the oxidation of λ³-imino-phosphines R  P  N  Ar ( 4b-d ) with sulfur and selenium. When P  (tert-butyl)iminophosphine, t-Bu  P  N-  Ar ( 4a ), was reacted with S₈ and Se_iv the corresponding oligomeric metaphosphonimidates 7, 8 were obtained. All new compounds are characterized by their NMR spectra. The constitution of the imino(thioxo)phosphorane 5d is proved by X-ray crystal structure determination.     

Reactions du pentachlorure de methyltungstene avec quelques coordinats du type oxo. Acces aux complexes des oxytrichlorure et dioxychlorure de methyltungstene(vi)

Stable MeWOCl₃ and MeWO₂Cl complexes were obtained in good yields by treating certain oxo-type ligands (i.e. OPR₃, OAsPh₃ or OSMe₂) either with MeWCl₅ or with MeWOCl₃, which were obtained from WCl₆ or WOCl₄ and HgCl₂.     

Kreuzkonjugierte Cyanine und Merocyanine aus Salzen 1-substituierter 2,3-Dimethylchinoxaline. 3. Mitteilung. Über die Indikatoreigenschaften der Farbbasen und die Tautomerie der konjugaten Farbsäuren

Crossconjugated Cyanines and Merocyanines, Obtained from Salts of 1-Substituted 2,3-Dimethylquinoxalines: On the Properties of the Dye Bases in Acidic Media UV./VIS. and ¹H-NMR. spectra of the indicator bases 1 in acidic solutions are presented. The solutions of the dye acids N and NN′ (Scheme 2) are in general not stable due to tautomerism. The relative pK_a-values are set in relation to data of equilibria and half-life periods. The latter ones depend on the substituents and on the acidity of the solutions. An inverse substituent effect observed in protic solvents is ascribed to solvolytic reactions. The dye base 1S (X = SO₃Na, R = C₆H₅) was synthesized starting with chlorobenzene. The cyanines 2 were obtained on treatment of 1 with HClO₄ in CH₃CN; solutions of 1 in H₂SO₄, however, yielded on dilution tautomeric salts that were isolated as the perchlorates 3 .     

Oligosaccharide Analogues of Polysaccharides. Part 2. Regioselective deprotection of monosaccharide-derived monomers and dimers

The Me₃Si? C(1) bond of the bis-(trimethylsilyl)ethynylated anhydroalditol 2 is selectively cleaved with BuLi to yield 3 / 4 , while AgNO₂/KCN in MeOH cleaves the Me₃Si? C(2′) bond, leading to 5 (Scheme 1). Both Me₃Si groups are removed with NaOH in MeOH (→ 7 ), the (i-Pr)₃Si group is selectively cleaved with HCl in aq. MeOH ( → 6 ); all silyl substituents are removed with Bu₄NF ( → 8 ). Acetolysis transformed 9 into 13 , which was desilylated to 14 , while thiolysis of 9 led to a mixture 11 / 12 . The tetraacetate 14 has also been obtained from 9 via 10 . Oxidative dimerisation of either 3 or 5 , or of a mixture 3 / 5 yields only the homodimers 15 and 16 (Scheme 2); treatment of 16 with AgNO₂/KCN yielded 17 , deprotection proceeding much more slowly than the cleavage of the Me₃Si? C(2′) group of 2 . The iodoalkyne 20 , required for the cross-coupling with 5 according to Cadiot-Chodkiewicz, was prepared by deprotection of 3 / 4 to 18 , methoxymethylation (→ 19 ), and iodination. Cross-coupling yielded mostly 21 , besides the homodimer 22 . Similarly, cross-coupling of 20 and 23 (obtained from 5 ) led to 24 and 22 . The structure of 24 was established by X-ray analysis (Fig.), showing a C(6)–C(5′) distance of 5.2 Å. The conditions for deprotecting 2 were applied to 21 , and led to 25 (AgNO₂/KCN), 26 (aq. NaOH), 27 (Bu₄NF), and 29 (HCl/MeOH; Scheme 3). Attempted deprotection of the propargylic-ether moiety with BuLi, however, failed. The dimer 27 was further deprotected to 28 . Acetolytic (Ac₂O/Me₃SiOTf) debenzylation of the dimer 30 , obtained from 10 , gave 31 (83%) which was deacetylated to 32 (Scheme 4). Cross-coupling of 5 and the bromoalkyne 33 , obtained from 10 , yielded 34 ; again, acetolysis proceeded well, leading to 35 . The cellobiose derivative 38 was prepared from the lactone 36 via 37 . The glycosidic linkage of 38 proved resistant to the conditions of acetolysis, leading to 39 . Acetolysis of the benzylated thiophene 40 (from 30 with Na₂S) yielded the octaacetate 41 , but proceeded in substantially lower yields (50%).     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XLIV. Tetrakis(alkoxycarbonylmethyl)titan-Verbindungen

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XLIII. Tetrakis(alkoxycarbonylmethyl)titanium Compounds Organotitanium(IV) compounds of the type (ROCOCH₂)₄Ti (R ? C₂H₅, i-C₃H₇, t-C₄H₉, C₆H₅, C₆H₅CH₂) were obtained by reactions of ROCOCH₂Li derivatives with TiCl₄ at low temperature. The compounds which decompose only above 90°C were characterized by the hydrolysis products, anaerobic reactions with iodine, and the i.r. spectra. The bond conditions are discussed.     

Effect of the nature of the active-component precursor on the properties of Pt/MgAlO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> catalysts in propane and <Emphasis Type="Italic">n</Emphasis>-decane dehydrogenation

The Pt/MgAlO _x catalysts, in which a mixed aluminum–magnesium oxide obtained by the heat treatment of corresponding layered double hydroxides was used as a support, were studied. The effects of the nature of active-component precursors ([PtCl₆]^2–, [PtCl₄]^2–, and [Pt₃(CO)₆] ₆ ^2- ), and the Mg/Al ratio in the support on the anchoring of complexes, the disperse state of platinum, and the properties of the obtained catalysts in the reactions of propane and n-decane dehydrogenation were found.     

Metall-Koordinationsverbindungen aus Essigsäure. I Chlorometallate(III) des Eisens,Chroms und Vanadiums

Metal Coordination Compounds Prepared in Acetic Acid. I. Chlorometalates(III) of Iron, Chromium, and Vanadium Ternary chloride-hydrates A₂MCl₅ · H₂O (A = Cs, Rb, (K)) can be precipitated with HCl from solutions of MCl₃ · 6 H₂O, (M = Fe, Cr, V) and alkali metal acetates in acetic acid. Under special conditions also compounds of the composition Cs₃MCl₆ · H₂O can be obtained. After dehydration of the solutions with acetyl chloride, anhydrous compounds are formed: Cs₃Fe₂Cl₉; A₃CrCl₆ and A₃Cr₂Cl₉ with A = Cs, Rb; Cs₃VCl₆ and Cs₃V₂Cl₉. V^III is partially oxidized to V^IV by an excess of acetyl chloride. Compounds A₂VCl₆ with A = Cs, Rb can be obtained more conveniently by the reaction of VOCl₂ · H₂O in acetic acid with acetyl chloride. The lattice parameters of some compounds were determined from powder patterns in analogy to known structure families.     

Transition metal iodates. VI. Preparation and characterization of the larger lanthanide iodates

In the continuation of this work, the Ln^III(IO₃)₃xH₂O type N compounds (abbreviated x_N) of La through Sm were prepared by precipitation, thermal decomposition, and by crystallization from the gel, from ambient and boiling water, and from boiling HNO₃. A total of 36 different compounds with 6 ? x ? 0 were obtained occurring in 12 structural types including one amorphous; in addition La₅(IO₆)₃ and four isostructural double salts of the type Ln(IO₃)₃·HIO₃ were obtained.Characterization techniques used included powder X-ray diffraction, differential thermal analysis, thermogravimetric analysis, second harmonic generation, and infrared spectroscopy.Out of the total of 16 crystalline iodate structures occurring for all the lanthanides, single crystals were obtainable in 11, comprising a total of 54 compounds.Including all the lanthanides (plus Y, less Pm), the x_N groups of isostructural compounds, with the number of compounds in parentheses, were the following: 6(1), 5_I(4), 5_II(2), 4(9), amorphous with 5 ? x ? 0 (15), 2_I(3), 2_II(9), 1(4), $\text{1}\text{2}\text{(2)}$, O_I(14), O_II(2), O_III(4), O_IV(3), O_V(4), and O_VI(1).     

Oligosaccharide Analogues of Polysaccharides. Part 7. Synthesis of a monosaccharide-derived monomer for amylose and cyclodextrin analogues

The synthesis of monomers of type C (Scheme 1) is described. In a first approach, chloro-acetyl-addition to the dioxolane 2 (Scheme 2), followed by treatment of the resulting chlorides 3 (α-D /β-D 1:3) with excess AgOTf and Bu₃SnC?CSiMe₃ gave the axial C-alkynyl-glycoside 4 (31%) and the C-arylglycoside 5 (29%). The structure of the dialkyne 6 , obtained by deacetylation of 4 , was established by X-ray analysis. The yield of the C-alkynyl-glycoside was slightly improved by protecting the C(4)-ethynyl group as the triethysilyl derivative, but not by substituting the benzyl by allyl or 2,6-difluorobenzyl groups. Silylation of the diol 1 with (chloro)diethyl[2-(trimethylsilyl)ethynyl]silane ( 19 ) resulted in 90% of the monosilyl ether 20 . HO? C(3) of 20 should favor coordination of a Lewis acid to O? C(6), and intramolecular, inverting acetal opening should lead to the product of axial alkynylation. Indeed, treatment of 20 with in situ generated BuAlCl₂, followed by treatment of the crude product with 0.1M HCl in MeOH, gave the dialkynylated triol 22 in yields of 85 to 90%. Under similar conditions, the disilyl ether 21 reacted more slowly to 22 (75%). The slower reaction correlates with the assumed intramolecular interaction of the precoordinated Lewis acid with O? C(6) in 20 .     

Room Temperature Synthesis and Characterization of Hybrid Materials of Polymethylhydrosiloxane Modified by Hydroxide Organic Compounds

New monolithic and transparent hybrid gels were obtained by reaction at room temperature of polymethylhydrosiloxane (PMHS) with 1,3,5-trihydroxybenzene (DO_1,3,5) and 2-hydroxybenzoic acid (DO₂), in tetrahydrofuran, using hexachloroplatinic acid (H₂PtCl₆·6H₂O) as catalyst. The products have been characterized by infrared and ²⁹Si MAS-NMR spectroscopy. The results show that the organic compounds have reacted with the PMHS, leading to monolithic and transparent gels in which organic-inorganic bridges were formed. An appropriate thermal treatment procedure was determined from TGA and DTA curves recorded on the hybrid gel powder after drying at 70 °C. The morphology and structure of the materials obtained were studied by scanning electronic microscopy (SEM) and X-ray powder diffraction (XRD).     

Preparation and Crystal Structure of PbRe2O6. An Example of the Re2O10 Unit with No Metal-Metal Bonding

Single crystals of PbRe₂O₆ were obtained from a stoichiometric mixture of PbO and ReO₃ at 500°C. The structure was determined by Patterson methods from X-ray four-circle diffractometer data using 2 270 (392 unique) reflections; R_W(F) = 0.036. PbRe₂O₆ crystallizes in the trigonal space group R3m with a = 10.359(6) Å, c = 11.092(6) Å and Z = 9. The compound is isotypic with the trigonal modification of PbNb₂O₆ and contains an Re₂O₁₀ unit. Unlike other compounds containing this species, there is no metal-metal bonding.     

Beiträge zur Organolanthanidchemie. II. Cylopentadienyllanthanid-1,3-butadien-Komplexe – Darstellung,Eigenschaften und Reaktionen

Contributions to Organolanthanide Chemistry. II. Cyclopentadienyllanthanide 1,3-Butadiene Complexes – Synthesis, Properties, and Reactions From cyclopentadienyllanthanide dihalides and “magnesium butadiene” Cp*La(C₄H₆) · MgI₂ · 3 THF ( I ), Cp*Ce(C₄H₆) · MgBr₂ · 2 THF ( II ), Cp*Nd(C₄H₆) · MgCl₂ · 2 THF ( III ), (1,3-(t-C₄H₉)₂C₅H₃)Nd(C₄H₆) · MgCl₂ · 2 THF ( IV ), CpEr(C₄H₆) · MgCl₂ · 2 THF ( V ) and (1,3-(t-C₄H₉)₂C₅H₃)Lu(C₄H₆) · MgCl₂ · 2 THF ( VI ) were obtained as highly air sensitive complexes which react easily with proton active compounds and molecules with multible bonds. The reaction products with diphenylamine and carbon dioxide Cp*Nd(NPh₂)₂ · NHPh₂ ( VII ) and Cp*Ce(O₂CC₄H₆CO₂) ( VIII ) are discribed. I–VIII were characterized by elementary analysis, i.r., ¹H and ¹³C n.m.r., and EI-MS spectra.