A novel synthesis of 4-propyl-2H-1-benzopyran-2-ones

Reaction of 2-hydroxybutyrophenones1–5 with ethoxycarbonylmethylenetriphenylphosphorane furnishes the 4-propyl-2H-1-benzopyran-2-ones6–10.

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Eine neue Synthese von 4-Propyl-2H-1-benzopyran-2-onen

Zusammenfassung Die Reaktion von 2-Hydroxybutyrophenonen1–5 ergab mit Ethoxycarbonylmethylentriphenylphosphoran die 4-Propyl-2H-1-benzopyran-2-one6–10

     

Molecular and crystal structure of the reaction product of 1-butyl-1-dibutylboryl-2-phenyl-2-diphenylphosphinoethene withtert-butylisocyanide

The structure of 4-hydroxy-4-[1-n-butyl-2-phenyl-2-(diphenylphosphino)ethenyl]-2-methyl-5,5-di-(n-butyl)-1-tert-butyl-1-aza-3-azonia-4-boratacyclopent-2-ene (I), the product of the reaction of the title compounds, has been established by X-ray structure analysis. The heterocycle has an envelope conformation, with the B atom deviating from the plane of four atoms. The distribution of bond lengths in the heterocycle is indicative of a delocalization in the N–C–N fragment. In the crystal, the molecules I form centrosymmetric dimers with the help of the H-bonds N–H...O. The hydroxyl group has a short intramolecular contact to the phosphorus atom, which can be interpreted as the hydrogen bond of the O–H...P type.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 3, pp. 91–95, May–June 1993.Translated by T. Yudanova.     

Co-hydrolysis products of tetraethoxysilane and methyltriethoxysilane in the presence of tetramethylammonium ions: Part 2 [1]

²⁹Si NMR peaks due to species with the double four-membered ring siloxane backbone composed of both Si(O^–)_4/2 and CH₃Si(O^–)_3/2 units, (CH₃) _n Si₈O _{20 – n} ^{/(8 – n) –} (n=1–3), formed by co-hydrolysis of tetraethoxysilane and methyltriethoxysilane in the presence of tetramethylammonium ions in methanol have been assigned. It has been found that ²⁹Si NMR peaks due to Si(OSi)₃(O^–) units shift to lower frequencies by replacement of the adjacent Si(O^–)_4/2 units by CH₃Si(O^–)_3/2 units, in other words, with increasing m value in Si[OSi(O^–)₃]_{3 – m} [OSi(CH₃) (O^–)₂] _m (O^–) (m=0–2). Peaks from CH₃ Si(OSi)₃ units in the species have also appeared as separated due to the kind of neighbor structural units. On the basis of the assignments, positions of CH₃Si(O^–)_3/2 units in the cubic octameric siloxane framework of (CH₃) _n Si₈O _{20 – n} ^{/(8 – n) –} (n=2, 3), for both of which three isomers are present, have been estimated.     

Blue-shifted hydrogen-bonded complexes. II. CH3F(HF)1 n 3 and CH2F2(HF)1 n 3

The equilibrium structures, binding energies, and vibrational spectra of the clusters CH₃F(HF)_{1 n 3} and CH₂F₂(HF)_{1 n 3} have been investigated with the aid of large-scale ab initio calculations performed at the Møller–Plesset second-order level. In all complexes, a strong C–FH–F halogen–hydrogen bond is formed. For the cases n = 2 and n = 3, blue-shifting C–HF–H hydrogen bonds are formed additionally. Blue shifts are, however, encountered for all C–H stretching vibrations of the fluoromethanes in all complexes, whether they take part in a hydrogen bond or not, in particular also for n = 1. For the case n = 3, blue shifts of the ν(C–H) stretching vibrational modes larger than 50 cm⁻¹ are predicted. As with the previously treated case of CHF₃(HF)_{1 n 3} complexes (A. Karpfen, E. S. Kryachko, J. Phys. Chem. A 107 (2003) 9724), the typical blue-shifting properties are to a large degree determined by the presence of a strong C–FH–F halogen–hydrogen bond. Therefore, the term blue-shifted appears more appropriate for this class of complexes. Stretching the C–F bond of a fluoromethane by forming a halogen–hydrogen bond causes a shortening of all C–H bonds. The shortening of the C–H bonds is proportional to the stretching of the C–F bond.     

Stereoselective epoxidation of 2-arylidene-1-indanones and 2-arylidene-1-benzosuberones

Summary Oxidation of the (E) and (Z) isomers of 2-arylidene-1-indanones (1) and 2-arylidene-1-benzosuberones (4) by alkaline hydrogen peroxide (methodi) afforded the spiroepoxidestrans-2a–g andtrans-5a–g from both isomers as sole products in high yields. On the other hand, dimethyldioxirane epoxidation(methodii) of the (E) isomers1a–g and4a–g gave the correspondingtrans spiroepoxides in good yields, whereas the (Z) isomers1a,c,e and4a,c,e led to thecis spiroepoxides in moderate yields. Dimethyldioxirane oxidation (methodii) of (Z)-1c and (Z)-4c,e gave diones3c and6c,e as by-products as well. Epoxidation of (Z)-1a,c,e and (Z)-4a,c,e bym-chloroperoxybenzoic acid (methodiii) resulted inca. 6:1 mixtures ofcis-2a,c,e andtrans-2a,c,e orcis-5a,c,e andtrans-5a,c,e spiroepoxides.Dedicated to Prof.W. Fleischhacker on the occasion of his 65^th birthday     

Some valence bond calculations for H2 with 1s and 2p basis sets

Summary The results ofab initio valence bond calculations are reported for H₂, with up to 16 nuclear centred and eight midbond 1s and 2p AOs included in them. The 24 AO calculation, with 116S=0 spin structures, gives an STO-6G energy of –1.17237 a.u., which is close to an MP4 estimate of –1.17256 a.u.     

Stereochemistry of acetoxymercuration of 1-methoxy-2-butyne

Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1843–1844, September, 1995.     

Theoretical study of bimolecular elimination (E2) reactions. Possibility ofsyn E2 elimination in the series of 2-R-2-R'-1-halocyclopropanes

Reactions of the methoxide ion with substituted halocyclopropanes, which result in E2 elimination, have been studied by the semiempirical quantum-chemical AM1 method. The transition states corresponding totrans andcis routes have been localized. The energetic predominance of thetrans route over thecis route is reduced by 2.6 kcal mol^–1 on going from 1-chloropropane to chlorocyclopropane because of the features of cyclopropane geometry. It has been demonstrated that, in the gas phase,cis elimination may predominate overtrans elimination for a particular stereoisomer of 2-cyano-2-methyl-1-halocyclopropanes due to weakening of orbital interactions and Coulomb repulsion between the cyano group and the MeO^– anion in thetrans E2 transition state.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 620–623, April, 1995.     

Heat capacity and other thermodynamic properties of CoTe2 from 5 to 1 030 K and of CoTe2.315 from 300 to 1 040 K

The heat capacity of orthorhombic (marcasite-type structure) cobalt ditelluride has been measured from 5 to 1 030 K by adiabatic-shield calorimetry with alternate energy inputs and equilibrations. Above 900 K a marked increase in heat capacity occurs which probably signals a change in the composition of the CoTe₂-phase towards higher tellurium content. Values at 298.15 and 1 000 K in J K^–1 mol^–1 of the heat capacity (C _p,m), entropy [S _m ^° (T)–S _m ^° (0)], andGibbs energy function – [G _m ^° (T)–H _m ^° (0)]T ^–1 are 75.23, 114.5, 49.93, and 132.4, 216.2, 139.17, respectively. Consistent with the metallic behavior of CoTe₂, deviation of the heat capacity from theDebye T ³-law was found at low temperatures. Comparison with the heat capacity of FeTe₂ shows aSchottky-like deviation with a maximum of 7.3 J K^–1 mol^–1 at 80 K and evidences the influence of the additional 3 d-electron in cobalt compared to iron. Heat capacity measurements were made on CoTe_2.33 to ascertain the existence range of the CoTe_2+x -phase and the entropy of the associated structural disorder.The portion of this research done at Ann Arbor was supported in part by the Structural Chemistry and Chemical Thermodynamics Program of the Division of Chemistry of the National Science Foundation under Grant No. CHE-7710049.     

Zum Spingleichgewicht5T2−1A1 in Fe(II)py 2 phen(NCS) 2

Zusammenfassung Die magnetischen, spektralen und strukturellen Eigenschaften des gemischten Amminkomplexes [Fe(II)py ₂ phen(NCS)₂] werden diskutiert. Der Orbitalparamter liegt mit 11 700 cm^–1 nahe der Spinpaarungsenergie für den mittleren kovalenten Fall 11 000 bis 12 000 cm^–1 und erlaubt so ein Spingleichgewicht zwischen den Spektralzuständen⁵T₂–¹A₁. Dieses Gleichgewicht wird durch magnetische Messungen bei verschiedenen Temperaturen nachgewiesen.

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On the spin equilibrium⁵T₂–¹A₁ in [Fe(II)py₂phen(NCS)₂]

The magnetic, spectral and structural properties of the mixed ammine [Fe(II)py ₂ phen(NCS)₂] are discussed. The orbital parameter of about 11 700 cm^–1 near to the spin-pairing energy for the mean covalent case 11 000 to 12 000 cm^–1 allows a spin equilibrium between the spectral states⁵T₂–¹A₁, put in evidence by the magnetic measurements at different temperatures.

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Mit 3 Abbildungen

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Herrn Prof. Dr.H. Nowotny gewidmet.     

1, 5-Rearrangement of enol acylates of aryl 1H.-1, 2, 4-triazol-1-ylmethyl ketones

The rearrangement of enol acylates of aryl 1H-1, 2, 4-triazol-1-ylmethyl ketones at 140–150°C in acetic anhydride is studied. The migration of the acyl group to the C(5) atom of the heterocycle is found to be intramolecular. The characteristics of the original and final products are presented. X-ray structural studies of the enol acetates of 2, 4-dichlorophenyl 1H-1, 2, 4-triazol-1-ylmethyl ketone and 2, 4-dichlorophenyl 5-acetyl-1H-1, 2, 4-triazol-1-ylmethyl ketone are carried out.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 560–564, March, 1993.     

Heterocyclization of 2-chloro-1-cyano-1-diethoxyphosphoryl-2-trifluoromethylethylene and 2-chloro-2-chlorodifluoromethyl-1-cyano-1-diethoxyphosphorylethylene

The reactions of 2-chloro-1-cyano-1-diethoxyphosphoryl-2-trifluoromethylethylene (2a) and 2-chloro-2-chlorodifluoromethyl-1-cyano-1-diethoxyphosphorylethylene (2b) with arylamines, arylhydrazines, amidines, 2-aminopyridines, and 5-aminopyrazoles were studied. Alkenes 2a, b can serve as precursors of aminopyrazoles, pyrimidines, pyrido[1,2-a]pyrimidines, and pyrazolo[1,5-a]pyrimidines modified with the fluoroalkyl and diethoxyphosphoryl groups. Intermediates of some heterocyclization reactions were detected by NMR spectroscopy. The structures of the compounds were confirmed by X ray diffraction analysis.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1977–1986, September, 2004.     

Extraction and spectrophotometric determination of titanium(IV) withN 1-hydroxy-N 1,N 2-diphenylbenzamidine and thiocyanate

A precise, reliable, sensitive, and selective method for the determination of titanium(IV) is described. Titanium(IV) reacts withN ¹-hydroxy-N ¹,N ²-diphenylbenzamidine (HDPBA) and thiocyanate to form an orange-coloured mixed-ligand complex of stoichiometry 112 (Ti SCN^– HDPBA). The complex is quantitatively extractable into toluene from 0.05–0.15M hydrochloric acid. The spectrum of the complex exhibits an absorption maximum at 400 nm with a molar absorptivity of 20000M ^–1 cm^–1 and the coloured system obeys Beer's law in the concentration range 0.20–3.0 gml^–1 titanium. The effects of foreign ions and of various experimental parameters have been studied to establish the optimum conditions for the extraction and determination of titanium. The precision of the method has been evaluated and the relative standard deviation has been found to be 0.53%. The method has been successfully applied to the determination of titanium in synthetic matrices corresponding to titanium-containing ores, minerals, and alloys.     

Cyclodextrin Complexation of the Stilbene 4-(2-(4-Tert-butylphenyl)ethen-1-yl)- benzoate and the Self-assembly of Molecular Devices

E-4-(2-(4- tert - butylphenyl) ethen-1- yl)benzoate, E-1^–, photoisomerizes to the Z-1^– isomer and vice versa in the free state and in the binary complexes 2·E-1^–, 2·Z-1^–, 3·E-1^– and 3·Z-1^– where 2 is the urea-linked cyclodextrin N-(6 ^A -deoxy--cyclodextrin-6 ^A - yl)-N-(6 ^A -deoxy--cyclodextrin-6 ^A - yl)urea and 3 is N,N- bis(6 ^A -deoxy--cyclodextrin-6 ^A - yl)urea. In 2·E-1^–and 3·E-1^– the stilbene occupies both cyclodextrin (CD) components of 2 and 3, whereas in 2·Z-1^– and 3·Z-1^– it only occupies one CD component while the other CD component is unoccupied. 4- tert - Butylphenolate, 4^–, and its carboxylate, 5^–, and sulfonate, 6^–, analogues form the ternary complex 2·Z-1^–·4^– and its analogues and also 3·Z-1^–·4^– and its analogues. These photoisomerize to 2·E-1^–and 3·E-1^– and either free 4^–, 57^– or 6^– and thereby function as molecular devices.     

Extended NMR Study of Spin-Crossover Compounds [Fe(1-alkyl-1H-tetrazole)6](BF4)2 and Their ZnII Analogs

A systematic NMR study was performed on several alkyl–tetrazole complexes of iron(II) and zinc(II) in the 10–300 K temperature range. The experiments were designed to separate the electronic and reorientational phase transitions caused by the spin crossover of the iron compounds from those independent of unpaired electrons. The ¹⁹F spectral data on the propyl-tetrazole compounds show that the electronic spin-transition has a strong effect on the spectra, and their behavior can be explained as a combined response to molecular reorientations and the spin transition. For these complexes, second-moment calculations revealed the strength of the interaction between resonant and nonresonant nuclei. Both of the applied NMR methods show irregularities at the temperature region between 70 and 120 K, suggesting the presence of a phase transition. The data also suggest two kinds of reorientational behavior for the BF₄ ^– counter ions. In the iron–ethyl–tetrazole compound, unlike in the propyl–tetrazole complex, a significant amount of unpaired electrons remains in their original high-temperature HS state. Above their effect, the behavior of the nuclear spins of the iron compound is basically governed by the same structural factors as in its zinc analog. The two-exponential behavior of the ¹H-T ₁ in case of the zinc–methyl–tetrazole compound can be explained on the basis of cross relaxation with the ¹⁹F nuclei due to the low ¹H/¹⁹F ratio. The presence of the two types of methyl reorientation is assumed to be the sign of the two different lattice sites known to be present in the Fe^II compound. The single-exponential T ₁ above T _c in the case of [Fe(mtz)₆](BF₄)₂ is consistently the sign of the strength of the paramagnetic relaxation observed in the ethyl and propyl compounds.     

Polarographic behaviour of 2-benzilidenimino-benzohydroxamic acid (2-BIBH) and 2-BIBH-Mo(VI) system

The polarographic behaviour of 2-benzilideniminobenzohydroxamic acid (2-BIBH) solutions and of 2-BIBH solutions in the presence of Mo(VI) have been studied by using differential pulse polarography and cyclic voltammetry. The polarographic characteristics of the resulting waves have been studied and possible mechanisms of the processes involved have been proposed. A linear relationship has been observed betweenI _p and Mo(VI) concentration in the range 2×10^–6 to 1.6×10^–5 M when using 3×10^–4 M 2-BIBH. Standard deviations of 5.6×10^–8 and 1.2×10^–8 M were found for 3×10^–6 and 8 × 10^–6 M Mo(VI), respectively.     

Stereospezifische Synthese und Konfiguration der (±)-threo-3-Dimethylamino-1-aryl-2-phenyl-1-propanole

Zusammenfassung Durch Reduktion von Dimethylamiden der 3-Hydroxy-2-phenyl-3-aryl-propansäuren mit LiAlH₄ wurde die stereospezifische Synthese von (±)-threo-3-Dimethylamino-1-aryl-2-phenyl-1-propanolen verwirklicht. Die Konfiguration der erhaltenen Verbindungen wurde durch spektralanalytische Aussagen über den Charakter der Wasserstoffbrückenbindung vom Typ–O–H...bestätigt.     

Photochemical and thermal transformations of diazo derivatives of 1-aryloxy- and 1-arylthio-2-aminoanthraquinones

In the photochemical and thermal decomposition of diazonium derivatives of 1-aryloxy- and 1-arylthio-2-aminoanthraquinones in CH ₃ COOH and dioxane, high yields of intramolecular arylation products — anthra-[2, 1-d]-4-tert-butylbenzo-[b]-furan-and anthra-[2, 1-d]-4-tert-butylbenzo-[b]-thiophene-8,13-diones — are formed. It was established that 2-azo derivatives of 1-aryloxy- and 1-acyloxyanthraquinones synthesized on the basis of the diazonium salts are stable under photolysis conditions.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 582–585, March, 1992.     

Fluoroalkylsilane Modification of Sol–Gel SiO2-TiO2 Coatings

Sol–gel chemistry of SiO_{2(1 – x)}TiO_2(x) involving the partial pre-hydrolysis of tetraethoxysilane (TEOS) and subsequent reaction with titanium isopropoxide has been used to produce materials of high area and variable absorption edge in the UV-visible spectrum. As x increases so the total surface area of these phases unexpectedly passed through a maximum, but the UV-vis cut off moved to greater wavelength. On the other hand, X-ray photoelectron spectroscopy (XPS) measured O_1s binding energies and temperatures of maximum rates of reduction (T_max) that were intermediate between those of pure SiO₂ and TiO₂. Both suggested that SiO_{2(1 – x)}TiO_2(x) samples were an intimate mixture of Si^{4 +} and Ti^{4 +} in the sol–gel matrix. Perfluoroalkylsilane (PFAS) was strongly adsorbed on this sol–gel coating making it strongly hydrophobic. This mode of modification was better than PFAS incorporation at the start of the sol–gel synthesis. Such sol–gel chemistry might in the future be optimised for water-repelling surfaces.     

Highly stereocontrolled boron-mediated synthesis of β-hydroxy-α-amino acids and dipeptides. Part 2

The chiral synthons 1(a–d) were submitted to boron-mediated asymmetric aldol condensation with acetaldehyde and benzaldehyde providing, in high diastereomeric excess (>95%), R,R-configured aldols 2(a–f) which are useful intermediates to enantiomerically pure β-hydroxy-α-amino acids.