Studies with enaminonitriles: Synthesis and chemical reactivity of 2‐phenyl‐3‐piperidin‐1‐yl acrylonitrile under microwave heating

Benzyl cyanide reacts with triethylorthoformate and piperidine in DMF solution to yield the title compound 2 . This reacted with aromatic amines to yield either aminoacrylonitriles or quinoline depending on reaction conditions and substitution pattern on the aromatic amine. The reaction of compound 2 with hydrazine hydrate could only be effected in the microwave oven and resulted in the formation of aminopyrazole 7 . Diazotization of 7 and coupling with an active methylene reagent afforded pyrazolo[5,1‐c]‐[1,2,4]triazine derivatives.     

Enzymatic Ring‐Opening Polymerization of Oxiranes and Dicarboxylic Anhydrides

Oxiranes, such as glycidyl phenyl ether, benzyl glycidate, glycidyl methyl ether, and styrene oxide, were copolymerized with dicarboxylic anhydrides, such as succinic anhydride, phthalic anhydride, and maleic anhydride, by the action of an enzyme in a stepwise reaction to produce the corresponding polyesters containing some ether linkages having a maximum M _w of 13 500. Oxiranes, such as glycidol and glycidyl phenyl ether, were also homopolymerized and copolymerized with other oxiranes by the enzyme to produce the corresponding polyethers.

Enzymatic polymerization of oxiranes and dicarboxylic anhydrides.     

Supramolecular Dynamics as Origin for Thermally Induced Insoluble‐to‐Soluble‐to‐Insoluble Transitions of Copolymers in Water

The synthesis of cationic mono‐(6‐O‐(1‐vinylimidazolium))‐ß‐cyclodextrin with toluenesulfonate as the corresponding anion is described. Free‐radical copolymerization of the resulting host–guest complex with N‐isopropylacrylamide or N,N‐diethylacrylamide yielded copolymers showing a temperature‐controlled solubility window in water. The impact of different anionic guests and salt concentrations on solubility behavior was investigated via turbidity measurements.

     

An efficient and facile microwave‐assisted synthesis of benzo[b][4,7]phenanthroline derivatives in water

A series of benzo[b][4,7]phenanthroline derivatives were synthesized via a three‐component reaction of aromatic aldehydes, 6‐aminoquinoline and either 1,3‐cyclohexanedione or dimedone in water under microwave irradiation without use of any catalyst. This method has the advantages of short reaction time, high yields, low cost and environmental friendliness as well as easy operation.     

Kinetics,mechanism, and endo selectivity of Diels–Alder reactions of alkylmonosubstituted ethenes with cyclohexa-1,3-diene in the gas phase

The reactions where Y = CH₃ (M), C₂H₅ (E), i? C₃H₇ (I), and t? C₄H₉ (T) have been studied between 488 and 606 K. The pressures of CHD ranged from 16 to 124 torr and those of YE from 57 to 625 torr. These reactions are homogeneous and first order with respect to each reagent. The rate constants (in L/mol·s) are given by The Arrhenius parameters are used as a test for a biradical mechanism and to discuss the endo selectivity of the reactions.     

Synthesis and in vitro antiproliferative activity of new substituted benzo[3′,2′:5,6]thiopyrano[4,3‐d]pyrimidines

The synthesis of new planar benzo[3′,2′:5,6]thiopyrano[4,3‐d]pyrimidine derivatives, carrying different side groups in the 2 position, is described. The novel substituted pyrimidines were obtained by reaction of the key intermediate 3‐dimethylamino methylen‐7‐methoxy‐2,3‐dihydrobenzo[3′,2′:5,6]thiopyran‐4(4H)‐one, characterized by a reactive group adjacent to the C?O function, with the suitable binucleophile amidines in a basic medium. All the new compounds were evaluated for the antiproliferative ability by an in vitro assay on two human tumour cell lines (HL‐60 and HeLa), and the 2‐phenyl substituted derivative showed the capacity to inhibit cell growth on HL‐60. Linear flow dichroism measurements indicated the inability to form a molecular complex with DNA.     

Assigning structures to [C2H3O]+ ions

The problem of assigning structures to [C₂H₃O]⁺ ions produced from a wide variety of precursor molecules has been readdressed. The identification of the acetyl cation, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{3}} \mathop {\rm{C}}\limits^{\rm{ + }} = {\rm{O}} $\end{document}, from metastable peak characteristics and collisional activation mass spectra appears to be straightforward. The structure \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{2}} = \mathop {\rm{C}}\limits^{\rm{ + }} - {\rm{OH}} $\end{document} is also known to exist as a stable ion. A third ion, whose structure may be represented as \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm{C}}\limits^{\rm{ + }} {\rm{H}}_{\rm{2}} {\rm{CHO}} $\end{document} or has also been characterized.     

Dipolmomente 1, 6-überbrückter [10]- Annulene

The dipole moments of 1, 6-bridged [10]-annulenes of type I (X = CH₂, O, NH) and of bromo derivatives with X = CH₂, O are in agreement with the previously established structure of these compounds if a partial moment of approximately 0,8 D is assigned to the non-planar π-electron system.     

An Efficient synthesis of pyrimido[4,5‐b]quinoline and indeno[2′,1′:5,6]pyrido[2,3‐d]pyrimidine derivatives via multicomponent reactions in ionic liquid

A series of pyrimido[4,5‐b]quinoline and indeno[2′,1′:5,6]pyrido[2,3‐d]pyrimidine derivatives were synthesized via the three‐component reaction of an aldehyde, 6‐aminopyrimidine‐2,4‐dione and 5,5‐dimethyl‐1,3‐cyclohexanedione or 1,3‐indanedione in ionic liquid 1‐n‐butyl‐3‐methylimidazolium bromide ([bmim]Br). This protocol has the advantages of easier work‐up, milder reaction conditions, high yields and an environmentally benign procedure compared with other methods.     

Zur Darstellung von Cyclophosphaten,Cyclophosphatophosphonaten, Diphosphonaten und Diphosphiten in Harnstoffschmelzen

Preparation of Cyclophosphates, Cyclophosphatophosphonates, Diphosphonates, and Di-phosphites in Urea Melts Ammonium cyclotriphosphate (NH₄)P₃O₉, ammonium cyclotetraphosphate [P^IV? P^IV ? O? ]₂, ammonium cyclotriphosphatophosphonates Ammonium organyldiphosphonates And ammonium diphosphites are prepared in high yields on heating acidic phosphates, phosphonates, and phosphites in urea or urea/ammonium nitrate melts. The mechanism of the dehydration of phosphorus compounds containing POH groups in molten urea is discussed.     

Oxazolidines versus schiff bases

The formation of oxazolidines from propionaldehyde and aliphatic β-aminoalcohols is complicated by the appearance of appreciable amounts of unsaturated Schiff bases. The simple Schiff base, often the dominant species when aromatic aldehydes react with amines, could not be detected in the present aliphatic systems. We conclude that in aliphatic systems the order of stability is and . The gem-dimethyl group α to nitrogen stablizes the heterocyclic ring remarkably.     

Electron impact studies. CVII—Negative ion mass spectra of the oxime group. Monoximes derived from α-dicarbonyl systems

Specific losses of water are observed from the molecular anions of monoximes of α-diketones. Labelling studies, kinetic energy release values and the +E spectra of ions have been used to aid in the elucidation of the fragmentation pathways. It is proposed that the majority of ions have α-keto nitrile structures.     

Effects of molecular weight,rubber toughening,and environment on fatigue crack propagation behavior of block amide copolymers

The Fatigue Crack Propagation (FCP) behavior of block amide copolymers is investigated as a function of molecular weight, rubber toughening as well as environmental conditions. The enhancement of FCP resistance with increasing average molecular weight is shown and correlated to features observed on the fracture surface. Particular attention is paid to hysteretic heating, measured with an infrared camera, in the crack tip zone of different average molecular weight copolymers and rubber-toughened copolymer. A FCP approach of stress-cracking in an aqueous solution of zinc chloride is proposed here. An improvement in FCP resistance as the average molecular weight increases, similar to that exhibited in normal environment, appears. The shift in da/dN values over the tested range of can be approximated by an exponential function:      

Design,synthesis and biological evaluation of novel 6,7,8,9‐tetrahydro‐2‐(2‐aryloxypyrimidin‐4‐yl)‐2H‐[1,2,4]triazolo[4,3‐a]azepin‐3(5H)‐ones

A series of novel 6,7,8,9‐tetrahydro‐2‐(2‐aryloxypyrimidin‐4‐yl)‐2H‐[1,2,4]triazolo[4,3‐a]azepin‐3(5H)‐ones were designed and efficiently synthesized. Their structures were determined by IR, ¹³C and ¹H NMR, mass spectroscopy, and elemental analysis. These compounds were screened for herbicidal activities against rape and barnyard grass. Compounds 5a‐5f and 5m exhibited moderate herbicidal activity against rape. In addition, the synthesis of the intermediate 1‐(azepan‐2‐ylidene)‐2‐(2‐chloropyrimidin‐4‐yl)‐hydrazine ( 3 ) was studied and the reason for the low yield in the initial procedure is discussed as well.     

[2, 3] Sigmatropic Rearrangements on Lithiation of Some Allyl Sulfides. Preliminary communication

In five cases, [2,3] sigmatropic rearrangement of the type has been observed.     

Eigenschaften und Verwendbarkeit des 10, 11-Dihydro-5H-dibenzo[a,d]cyclohepten-5-yl-Rests (= 5-Dibenzosuberyl-Rests) als neue Schutzgruppe für Amine,Aminosäuren,Alkohole, Thiole und Carbonsäuren

Properties and suitability of the 10,11-dihydro-5 H-dibenzo[a, d]cyclohepten-5-yl group (= 5-dibenzosuberyl group) as a new protecting group for amines, amino-acids, alcohols, thiols and carboxylic acids. The 10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-yl group (5-dibenzosuberyl group): has been found useful for protecting amines, alcohols, thiols, and carboxylic acids. Furthermore, the investigated 5-amino compounds are extremely stable in strongly acidic media (e. g. in hydrogen bromide) and still the amino group is easily cleaved under mild conditions, such as those used for N-trityl compounds (e.g. boiling in dilute acetic acid or catalytic hydrogenation). Hence this ring system could be a valuable and adaptable protecting group, especially in peptide chemistry.     

Synthesis of a New Thiophene/Quinoxaline CT‐Type Copolymer with High Solubility and Its Basic Optical Properties

A new π‐conjugated charge‐transfer‐type copolymer of electron‐donating thiophene and electron‐accepting quinoxaline was prepared by organometallic polycondensation. The polymer was soluble in organic solvents such as tetrahydrofuran, and showed a UV‐vis peak at long wavelengths of 598 nm in chloroform and 629 nm in the film. Its film exhibited a χ⁽³⁾ peak in the resonance region with a χ⁽³⁾ value comparable to that of regioregular head‐to‐tail poly(3‐hexylthiophene‐2,5‐diyl).

     

Universal Methodology for Block Copolymer Synthesis

Chemoselective stepwise coupling between living polymers and a heterobifunctional linking agent is shown to be a versatile, facile, and efficient methodology for block copolymer synthesis. This protocol is based on the quantitative formation of the end‐functionalized precursor in the first coupling step. In this proof‐of‐concept study, we investigate the behavior of specific macroanions, prepared through living anionic polymerization (LAP). Nevertheless, the applicability range is becoming exceptionally wide upon transformation reactions, e.g., by tailoring the chain‐termini nucleophilicity via endcapping. This novel protocol will considerably expand the limits of LAP, rendering viable the construction of advanced and tailor‐made materials via an effortless pathway.