Synthesen von β-Fur-2-yl-α-halogenacrylonitrilen

Syntheses of β-Fur-2-yl-α-halogenacrylonitriles Syntheses of β-fur-2-yl-α-halogenacrylonitriles 2a–f by Wittig-olefination of furfurales, Hunsdiecker-reaction of β-(5-nitro-fur-2-yl)-α-cyanoacrylic acid 3 , halogenation of β-fur-2-yl acrylonitriles and reaction of furfurales with β-azido-α-halogen-γ-methoxy-Δ^α,β-crotonolactones 9 are described.     

Reaktivität und Selektivität bei der Oxidation von Styrolderivaten. IV. Untersuchungen zur Oxidation von substituierten β,β-Dimethylstyrolen

Reactivity and Selectivity in the Oxidation of Styrene Derivatives. IV. Studies on the Oxidation of Substituted β,β-Dimethylstyrenes The liquid phase oxidation of substitued (p-MeO-, p-Cl-, m-CF₃-) 2-aryl-3-methyl-but-2-enes, of 1,1-diphenyl-2-methyl-propene, of 1-ethoxy-2-methyl-1-phenyl-propene and of 9-isopropylidene-fluorene with pure oxygen was investigated in chlorobenzene solution and in presence of cumene and of cumene hydroperoxide in the temperature range 65-125 °C. The product yields were determined gaschromatographically. The differences of the activation energies of epoxide formation and the parallel reactions were calculated. They amount to 19–48 kJ/mol. The epoxide selectivity increases with increasing temperature and increasing concentration of olefin. The relative chain propagation constants (k_{pC C}) were determined by competitive oxidation with cumene. The k_{pC C} values of substitued β,β-dimethylstyrenes can be correlated by a LFE-relationship with the ionisation energies of the olefins.     

β-Fur-2-yl-α-halogenacrylonitrile. VIII. Konformationsuntersuchungen an substituierten β-Fur-2-yl-acrylonitrilen

β-Fur-2-yl-β-halogenacrylonitriles. VIII. Investigations of the Conformation of Substituted β-Fur-2-yl-acrylonitriles X-ray analysis, n.m.r.-investigations in the presence of Eu(FOD)₃ and NOE-measurement indicate, that the E-isomer of β-substituted β-fur-2-yl-acrylonitriles exist in the s-cis conformation, whereas the E-isomer of the α-substituted β-fur-2-yl-acrylonitriles prefer the s-trans-conformation. The influence of the configuration and conformation on the chemical shift of the H-3-furan protons is discussed.     

Reaktionen von β-Chlorvinylaldehyden. V [1]. Zur Bildung von 2,2′-Thiopyrylotrimethinfarbsalzen aus 2-(α-Formylalkyliden)-2H-thiopyranen

Reactions of β-Chlorovinylaldehydes. V. The Formation of 2,2′-Thiopyrylocyanine Dyes from 2-(α-Formylalkylidene)-2H-thipyranes Substituted β-chlorocrotonaldehydes react with Na₂S · 9H₂O to form 2-(α-formyl-alkylidene)-2H-thiopyranes 1 . The corresponding thiopyrylium salts 2 which are easily available from 1 and strong acids exist in the enolic form (2-β-hydroxyvinyl-thiopyrylium salts). They are converted at room temperature in methanol solution to dark green compounds, which are identified as 2,2′-thiopyrylotrimethincyanine dyes 3 . The mechanism of formation of compounds 3 is discussed.     

β-Fur-2-yl-α-halogenacrylonitrile. I. Darstellung von β-Fur-2-yl-ß-aminoacrylonitrilen und β-Fur-2-yl-α-aminoacrylonitrilen

β-Fur-2-yl-α-halogenacrylonitriles. I. Preparation of β-Fur-2-yl-ß-aminoacrylonitriles and β-Fur-2-yl-α-aminoacrylonitriles β-Fur-2-yl-α-halogenacrylonitriles 1 react with secondary amines to yield β-fur-2-yl-ß-aminonitriles 2 and β-fur-2-yl-α-aminoacrylonitriles 3 . The ¹ H-n.m.r. spectra of the E/Z isomers are discussed.     

Furylvinylhalogenide. IX. Reaktionen von β-Fur-2-yl-β-chlor-α-cyanacrylsäureestern mit Aminen

Furylvinylhalides. IX. Reactions of β-fur-2-yl-β-chloro-α-cyanoacrylates with amines β-Fur-2-yl-β-chloro-α-cyanoacrylates 4 react with amines to yield β-Fur-2-yl-β-amino-α-cyanoacrylates 5 . The ¹H-n.m.r. spectra of 5 are discussed.     

Ionic graft copolymerization. VI. Graft copolymerization of β-propiolactone and N-vinylcarbazole onto trunk polymer containing carboxylic acid,sulfonic acid,and their salts

It was pointed out in previous papers that both cationic and anionic polymerization might be involved simultaneously in grafting onto trunk polymers containing ? COOH or ? SO₃Na. The graft copolymerization of β-Propiolactone (βPL)–N-vinylcarbazole (NVCZ) onto styrene-divinylbenzene copolymers containing carboxylic acid, sulfonic acid, and their salts was carried out in order to distinguish between the polymers produced by anionic and cationic mechanisms. The polymer obtained by the polymerization of βPL–NVCZ with BF₃·OEt₂, a typical cationic catalyst, consisted mainly of NVCZ units, but the polymer obtained with BuLi, a typical anionic catalyst, consisted mainly of βPL units. In the graft copolymerization of NVCZ–βPL onto trunk polymer containing ? COOH, the NVCZ contents of the branch polymer and the tolueneinsoluble fraction were estimated to be ca. 50 mole-%; therefore these polymers were produced by both cationic and anionic mechanisms. In the case of graft copolymerization onto the trunk polymer containing SO₃Na, it was found that both cationic and anionic polymerization also occurred simultaneously.     

Photochemie von Aminoketonen. IV [1]. Synthese von 3-Aryl-pyrrolidinolen-(3) durch Photocyclisierung von β-Amino-propiophenonen

Photochemistry of Aminoketones. IV. Synthesis of 3-Aryl-pyrrolidinols-(3) via Photocyclization of β-Amino-propiophenones Photolysis (λ_irr ≥ 300 nm) of N-benzyl-N-benzoyl-β-aminopropiophenones 6–9 in abs. ether affords a 47–50% yield of N-benzoyl-pyrrolidinols 12–18 . The relative configurations of the diastereomeric 12–18 are determined by ¹H-n.m.r. spectroscopy. The different behaviour of the N-acylated 6–9 in contrast to N,N-dialkyl-β-aminopropiophenones is explained by assumption of a dipol-dipol interaction between the keto and the amido carbonylgroups in the n,π*-excited state.     

Mechanistic and catalytic studies of β‐nitroalcohol crosslinking with polyamine

β‐Nitroalcohols (βNAs) are promising corneoscleral crosslinking agents for the treatment of diseases such as keratoconus and myopia. Although it is believed that formaldehyde is released from the crosslinking reactions of βNAs, the mechanism by which βNAs react with amine‐functionalized polymers has yet to be known. In this study, we present the reaction mechanism of the βNA crosslinking. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) data provide strong evidence that formaldehyde is released during the reaction. Catalytic studies show that sodium bicarbonate (NaHCO₃) and salmon testes DNA accelerate the reaction while hydroxynitrile lyase from Arabidopsis thaliana decelerates the crosslinking reaction. These results suggest that βNAs are potential self‐administered crosslinking agents for future clinical use. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

β-Ketoester — a Rearranged Product of Epoxidation of α, β-Unsaturated Methyl Ester

Attempted epoxidation of long-chain α,β-unsaturated esters resulted in the formation of the rearranged products of the corresponding epoxyesters. It was observed that reaction of peracids with esters of C₁₆, C₁₈ and C₂₂ trans-2-enoic acids, instead of yielding the expected epoxides, gave the isomerized products characterized as β-ketoesters. The structure of β-ketoester as saturated 3-oxoester was unambiguously established by chemical methods as well as by IR, NMR and Mass spectrometry. The selectivity of this rearrangement provides a useful synthetic pathway for the preparation of β-ketoesters.     

β-Fur-2-yl-α-halogenacrylonitrile. VII. Reaktionen von β-(5-Brom-fur-2-yl)-α-bromacrylonitril mit Mercaptan,Thioharnstoff und Thioharnstoffderivaten

β-Fur-2-yl-α-halogenacrylonitriles. VII. Reactions of β-(5-Bromo-fur-2-yl)-α-bromoacrylonitriles with Mercaptans, Thiourea and Thiourea Derivatives β-(5-Bromo-fur-2-yl)-α-bromoacrylonitrile 1 reacts with ethylmercaptan to yield β-(5-bromo-fur-2-yl) β-ethylthioacrylonitrile 3 . With thiourea β,β′-thio-bis[β-(5-bromo-fur-2-yl)]-acrylonitrile 2 is formed. The pyrimidines 4 and 5 have been prepared by the reaction of 1 with s-methylthiourea and 2-aminothiazole, respectively. The structure of the new compounds were determined by means of x-ray analysis, ¹H-n.m.r., ¹³C-n.m.r. and mass-spectroscopy.     

Structure-activity relations of β-adrenergic agents

A review of the structure-activity relations in aryloxypropanolamine β-adrenoceptor drugs is presented. The effect of substitution in various parts of the molecule on β₁/β₂ selectivity and degree of partial agonism is discussed. Cardiac (β₁) selectivity is achieved by hydrophilic compounds with either p-amide substitution in the aryl ring, or a hydrogen bonding group in the amine side chain. Lipophilic compounds with branched chains tend to be β₂ selective. Partial agonist activity may also be controlled by hydrogen bonding groups in the side chain and by aromatic substitution. Here 3,4-dihydroxyl groups give full agonists, mono-and des-hydroxy (OH) groups partial agonists. The size of any o-substituent is critical and a plot of Taft's steric factor versus partial agonism gives a linear relation. By manipulation of the above factors all combinations of selectivity and agonist activity may be achieved.     

Vinyloge Acylverbindungen. XX. Reaktivität und Toxizität arylsubstituierter β-Chlorvinylketone, β-Chlorvinylaldehyde und β-Chlorvinylmethyleniminiumsalze

Vinylogous Acyl Compounds. XX. Reactivity and Toxicity of Aryl-substituted β-Chlorovinyl Ketones, β-Chlorovinyl Aldehydes, and β-Chlorovinyl Methyleniminium Salts Based on kinetic measurements, the nucleophilic replaceability of the chlorine in aromatic β-chlorovinyl ketones ArCO-CH  CH-Cl ( 1 ), isomeric β-chlorovinyl aldehydes OCH CHC(Cl)Ar( 2 ), and corresponding β-chlorovinyl methyleniminium salts Me₂N^⊕;CH CHC(Cl)Ar X^⊖ ( 3 ) is compared and related to toxicological findings. The chemical reactivity of these important synthetic building blocks increases in the order 2 < 1 < 3 , the acute toxicity (24 h LD₅₀ i. p. in the mouse) shows the graduation 2 < 3 < 1 . Compounds of type 1 prove to be relatively toxic (LD₅₀ 24–42 mg/kg) and display a marked necrotic action after percutaneous absorption, whereas the aldehydes 2 have not only a minor acute toxicity (LD₅₀ 158–298 mg/kg) but also a somewhat less marked skin damaging activity. In addition, the LD₅₀ values of selected β-chlorovinyl carbonyl compounds are compared with those of corresponding halogen-free compounds as well as of vinylogous carbonamidium salts ArCO CHCH N^⊕R₃X^⊖. The latter, which can be used as synthetic equivalents of 1 , differ in both the reduced acute toxicity and missing skin damaging properties.     

A Combined High‐Resolution Mass Spectrometric and in silico Approach for the Characterisation of Small Ligands of β2‐Microglobulin

β₂‐Microglobulin (β₂‐m) is a protein responsible for a severe complication of long‐term hemodialysis, known as dialysis‐related amyloidosis, in which initial β₂‐m misfolding leads to amyloid fibril deposition, mainly in the skeletal tissue. Whereas much attention is paid to understanding the complex mechanism of amyloid formation, the evaluation of small molecules that may bind β₂‐m and possibly inhibit the aggregation process is still largely unexplored mainly because the protein lacks a specific active site. Based on our previous findings, we selected a pilot set of sulfonated molecules that are known to either bind or not to the protein, including binders that are anti‐amyloidogenic. We show how a complementary approach, using high‐resolution mass spectrometry and in silico studies, can offer rapid and precise information on affinity, as well as insight into the structural requisites that favour or disfavour the inhibitory activity. Overall, this approach can be used for predictive purposes and for a rapid screening of fibrillogenesis inhibitors.     

The copolymerization of carbon dioxide and propylene oxide with Y(CCl<Subscript>3</Subscript>COO)<Subscript>3</Subscript>-diphenylzinc-glycerol catalyst

Summary  Various organometallic compounds (diphenylzinc, dibenzylzinc, dicyclohexylzinc, bis(pentafluorophenyl)zinc, diethylzinc, di(n-butyl)zinc, triethylaluminum) were used to form Y(CCl₃COO)₃-organometallic compound-glycerol catalyst for the copolymerization of carbon dioxide and propylene oxide. It was found that Y(CCl₃COO)₃-diphenylzinc-glycerol catalyst showed the highest catalytic activity, at optimum conditions the yield could be as high as 478.8 (g polymer/mol Zn h). The catalytic activity sequence of these catalysts decreased as follows: Y(CCl₃COO)₃-diphenylzinc-glycerol>Y(CCl₃COO)₃-diethylzinc-glycerol>Y(CCl₃COO)₃-di-(n-butyl)zinc-glycerol>Y(CCl₃COO)₃-dibenzylzinc-glycerol>Y(CCl₃COO)₃-dicyclohexylzinc-glycerol>Y(CCl₃COO)₃-bis(pentafluorophenyl)zinc-glycerol. ¹H NMR, ¹³C NMR, TGA, DMA, tensile tests results indicated that microstructure and properties of the polymers varied with catalyst used. Copolymer from Y(CCl₃COO)₃-diphenylzinc-glycerol catalyst displayed the highest thermal properties and mechanical properties: the glass transition temperature (T_g) was 50.2 ^oC, the 5% weight loss temperature (T_-5%) was 222 C, the tensile strength was 34.7 MPa, the Young’s modulus was 298 MPa. The difference between the properties of the polymers was explained relating to the different polycarbonate content in the polymers.     

β-Thiocyanatovinylcarbonylverbindungen. II. Darstellung von 4,5-substituierten Isothiazolen

β-Thiocyanato-vinylcarbonyl Compounds. II. Preparation of 4,5-Substituted Isothiazoles Z-β-Thiocyanato-vinylaldehydes cyclize with liquid ammonia to isothiazoles. A new synthesis for 4- and/or 5-alkyl, cycloalkyl- or aryl-substituted isothiazoles by direct reaction of Z/E-β-chlorovinylaldehydes with ammonium thiocyanate in boiling acetone is presented. As a third procedure, the reaction of β-thiocyanato-vinylaldehydes with NH₄SCN in acetone is convenient. The obtained 4,5-substituted isothiazoles were characterized by their u. v. and n. m. r. spectra and perchlorates.     

Furylvinylhalogenide. X [1]. Reaktionen von β-Fur-2-yl-β-chlor-α-cyanacrylsäurederivaten mit Hydrazinen

Furylvinylhalides. X. Reactions of β-Fur-2-yl-β-chloro-α-cyanoacrylic Acid Derivatives with Hydrazines β-Fur-2-yl-β-chloro-α-cyanoacrylic acid derivatives 3 react with hydrazines yielding 3-fur-2-yl-5-aminopyrazoles 5 or 3-fur-2-yl-4-cyanpyrazolin-5-ones 6 . In some cases the β-hydrazino-α-cyanoacrylic acid derivatives 4 , could be isolated.     

Zur Synthese CF3-substituierter Chinoline aus β-Chlor-β-trifluormethyl-vinylaldehyden. I

Synthesis of CF₃-Substituted Quinolines from β-Chloro-β-trifluoromethyl-vinylaldehydes. I 3-(Trifluoromethyl)-acroleines 2 have been synthesized through VILSMEIER's reaction from α-Trifluoro-methylketones 1 . The reaction of 2 with anilines and naphthylamines gives in good yields 2-trifluoromethylquinolines 4 and benzoquinolines 5 .     

On the Crystal Structure of the β′-Form of Triglycerides and Structural Changes at the Phase Transitions LIQ. → α → β′ ← β

Based on X-ray single crystal data of the β′-form of triundecanoin the general features of the molecular arrangement in this crystal form have been derived. The unit cell contains eight molecules arranged according to space group P2_1/c, with alternation of the tilt of the hydrocarbon chains in adjacent bimolecular layers. The structure within the molecular layer is quite similar to that of the β-form; the main difference being the chain packing. A second β″-form, β′₂, of triundecanoin has been observed and it differs from the one mentioned above in the orientation of the chain packing subcell 0° in relation to the true unit cell. The polymorphic transitions have been followed by recording of the diffraction pattern versus temperatures. The polymorphic transitions α · β′ · β can be regarded mainly as different lateral arrangement of a dimeric unit. In the α-form the chains are disordered near the methyl end groups, and due to this disorder the structure is closely related to the lamellar liquid-crystalline phase. It is also possible to classify β′-forms according to short-spacing data into a β′₁-type and a β′₂-type, and these groups can be identified also in complex triglycerides.     

Optisch aktive O-Silyl-β-dicarbonylverbindungen. IV. Transsilylierungsreaktionen

Optically Active O-Silyl-β-dicarbonyl Compounds. IV. Transsilylation Reactions The relationship between the structure of O-silyl-β-dicarbonyl compounds and their tendency to transsilylation reactions is studied by gas chromatography. It is shown that the silyl derivatives of β-diketones and β-dicarboxylic acid diesters easily undergo intermolecular mutual transsilylation reactions. The same compounds quickly transfer silyl groups to free β-dicarbonyl compounds. On the contrary, with silyl derivatives of β-keto esters, o-acylphenols and salicylic acid esters no transsilylation reaction could be observed, and the transfer of silyl groups from O-silyl-β-keto esters to free β-keto esters is only very slow. The ease of transsilylation reactions of O-silyl-β-dicarbonyl compounds correlates with the velocity of racemization of optically active O-silyl-β-dicarbonyl compounds of the same structure. Therefore, we assume that intermolecular transsilylation reactions with inversion of configuration are the main reason for the racemization of optically active O-silyl-β-dicarbonyl compounds. However, no connection could be found between the tendency to transsilylation reactions and the stereochemistry of the reactions of optically active O-silyl-β-dicarbonyl compounds with LiAlH₄ which is also dependent on the structure of these compounds.