Hydrochlorination of δ2-1,3-oxazolines and 1,3-oxazolidines

The compounds 2-(ethoxycarbonylmethyl)-²-l,3-oxazoline and 1-methyl-2-(methoxycarbonylmethylene)-1,3-oxazolidine are hydrochlorinated at the C=N or C= C bond, respectively, with subsequent opening of the oxazolidine ring. Depending on the reaction conditions, this occurs regioselectively to form various products.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 684–686, May, 1992     

Synthesis of Some Potential Antiangiogenic 1,3-Dihydro-1,3-dioxo-2H-isoindole Derivatives

The proliferation, invasion and metastasis of malignant tumors are closely related withangiogenesis induced by tumor cells. Blocking tumor-induced angiogenesis is anefficient strategy to prevent and cure cancer1. Recent studies indicated that theangiogenic process depends on vascular endothelial cell migration and invasion, whichregulated by αvβ3 receptor2. The receptor and extracellular matrix can recognize eachother through Arg-Gly-Asp (RGD) consensus sequence found in matrix ligands…     

Conversion of ethanol to 1,3-butadiene over Ag-ZrO2/SiO2 catalysts:The role of surface interfaces

A series of Ag-ZrO₂/SiO₂ catalysts with different metal-support interfaces were synthesized in an effort to elucidate the roles of specific interfaces in controlling the ethanol to 1,3-butadiene conversion and selectivity.According to the results of detailed characterizations(e.g.CO/pyridine-DRIFTS,XPS,TEM,NH3-TPD,and ¹H MAS NMR),it was found that the Ag-O-Si interfaces significantly enhanced the dehydrogenation of ethanol while the presence of ZrO₂ improved the interaction between Ag and ZrO₂/SiO₂,creating more Ag^δ+active sites.The high dispersion of ZrO₂ on SiO₂ generated abundant Zr-O-Si interfaces with medium and weak Lewis acidity,promoting the condensation of acetaldehyde to crotonaldehyde.These Zr-O-Si interfaces in close interaction with Ag^δ+species played a critical role in the enhanced H transfer during the MPV reduction of crotonaldehyde to crotyl alcohol.The synergies among the interfaces resulted in retarded ethanol dehydration reactivity,balanced ethanol dehydrogenation and condensation reactions,and a subsequent high 1,3-butadiene yield.     

Metal derivatives of 1,3-bis(2-pyridyl)-1,3-propanedione and N,N′-dimethyl-1,3-bis(2-pyridyl)-1,3-propanedione

Complexes of transition metal ions with the oxygen-nitrogen containing ligand 1,3-bis(2-pyridyl)-1,3-propanedione (bpypH) have been synthesized. These present stoichiometries which do not conform with the usual tendency manifested by β-diketones, since molecular formulas with the composition M(bpyp)X are found. A nitrogen methylated ligand N,N′-dimethyl-1,3-bis(2-pyridyl)-1,3-propanedione methyl sulphate [dimebpypH] (MeSO₄)₂ has also been synthesized and its complexes with transition metal ions studied. The stoichiometries now, resemble those of typical β-diketones, namely [dimepyp]₂MX₄ with four anions because of the dicationic nature of the original ligand. This, together with IR evidence suggests a dual type of coordination by bpip via the β-diketone and the pyridyl moieties.     

β-Olefination of 2-alkynoates leading to trisubstituted 1,3-dienes

A phosphine-mediated olefination of 2-alkynoates with aldehydes forming 1,3-dienes with high E-selectivity and up to 88% yield is described. Reaction conditions are optimized and reactions are demonstrated for various aryl, alkyl, and alkenyl aldehydes and for ethyl 2-alkynoates with different substituents in the δ-position. Proof of concept is shown for the generation of a β,γ-unsaturated lactone by intramolecular olefination, and furthermore the use of the generated 1,3-dienes in the Diels-Alder reaction has been demonstrated.     

SEC–MALLS analysis of cellulose using LiCl/1,3-dimethyl-2-imidazolidinone as an eluent

The lithium chloride/1,3-dimethyl-2-imidazolidinone (LiCl/DMI) solvent system for cellulose was adopted as a mobile phase of size-exclusion chromatographic (SEC) analysis of cellulose, and the applicability of this system was examined using multi-angle laser light scattering and ¹³C-NMR analysis. The results indicate that 8% (w/v) LiCl/DMI ID a true solvent for cellulose, and that cellulose molecules dissolving ID 1% (w/v) LiCl/DMI are separated orderly depending on their molecular mass (MM) or root-mean-square (RMS) radius by the SEC system. Practically, no aggregates were detected ID the dilute cellulose/LiCl/DMI solutions. Furthermore, high stability of cellulose/LiCl/DMI solutions has been demonstrated; only a few percent of decline ID average MM was observed even after storage for 6 months at room temperature. Relationships between RMS radius and MM for hardwood bleached kraft pulp ID 1% LiCl/DMI was estimated as the following equation: _g^0.59, corresponding to a Mark–Houwink–Sakurada exponent of 0.77.     

Synthesis of 2-Ferrocenyl-2-(Dialkyl Hydroxymethyl)D-1,3-Dithianes

The reactions of lithiated 2-ferrocenyl-1,3-dithiane with alkyl carbonyl compounds are studied. Fifteen of title compounds which are new ferrocene derivatives were synthesized and structurally characterized by elemental analysis, IR and 1H NMR spectra. The 1H NMR spectra of the dithiane compounds are briefly discussed.     

Reactions of enamines with fluorinated acyl chlorides----Synthesis of fluorinated 1,3-diketones and 1,3-keto-aldehydes

The reactions of enamines (1a-b,4,6) with fluorinated acyl chlorides (2a-d) produced fluorinated 1,3-diketones (3a-f) and 1,3-keto-aldehydes (7a-c) in good yields as well as byproducts fluorinated acylamides (5a-c).It is proposed that the reactions involve nucleophilic attack by the C-atora and/or N-atom of the enamines on acyl carbon of the fluorinated acyl chlorides.     

Synthesis of 5-Fluoroalkyl Isoxazolidines via 1,3-Dipolar Cycloaddition of Ethyl 2-Hydropolyfluoroalk-2-enoates with Nitrones

1,3-Dipolar cycloaddition reactions of ethyl 2-hydropolyfluoroalk-2-enoates (1) with some nitrones were described. The reaction of 3,4-dihydroisoquinoline N-oxide (2) with 1 took place readily in methylene chloride at room temperature to give the corresponding 5-fluoroalkylisoxazolidines regioselectively as a mixture of two diastereoisomers (trans and cis) in high yields, while longer reaction time and higher temperature were needed in the case of non-cyclic nitrones. Under similar conditions the reaction of quinoline N-oxide (14) with 1 did not give the expected adducts and a ring-opening product was obtained.     

Direct synthesis of novel 2-imino-1,3-selenazolidine derivatives from O-methanesulfonyl β-amino alcohol hydrochlorides

Recently, we have reported that 4,5-dialkylsubstituted 2-imino-1,3-azolidine derivatives (1) strongly inhibit inducible nitric oxide synthase (iNOS). To our knowledge, only few methods have been reported for the synthesis of 4,5-dialkylsubstituted 2-imino-1,3-selenazolidine derivatives (2), which are the selenium analogue of 1. Herein, we report the direct synthesis of 2 from the corresponding O-methanesulfonyl β-amino alcohol hydrochlorides using potassium selenocyanate and evaluation for the inhibitory activity against iNOS of the newly synthesized selenazolidine derivatives.     

Reaction characteristics of cellulose in the LiCl/1,3‐dimethyl‐2‐imidazolidinone solvent system

In order to elucidate the nature of the LiCl/1,3dimethy2imidazolidinone (DMI) solvent system as one of the homogeneous reaction media of cellulose, cellulose acetate (CA) and Omethylcellulose (MC) were prepared using this solvent system, and the distribution of substituents within anhydroglucose units was examined by ¹³CNMR. It was found that (i) homogeneous cellulose solutions can be easily prepared by heating 2, 5–12 and 100 parts of weight of cellulose, LiCl, and DMI, respectively, and (ii) the relative reactivity of hydroxyl groups is in the order C6 > C2 > C3 for both CA and MC. A remarkable feature of this solvent system is that the reaction efficiency in etherification is very high compared with other homogeneous solvent systems.     

Natural effectors of β-1,3-glucanases activator of the β-1,3-glucanases of marine mollusks

The capacity of certain extracts of marine invertebrates of the Indian and Pacific Oceans for activating -1,3-glucanases has been detected. It has been shown that an individual compound — swinholide A from the spongeTheonella swinhoei — specifically activates -1,3-glucanases of bivlve mollusks. In the presence of swinholide A both the hydrolysis of laminarin by -1,3-glucanase L-IV fromSpisula sachalinensis and the transglycosylation reaction are accelerated.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 316–320, May–August, 1992.     

Reactions of 2-(2-chloro-4,5-dihydro-3-furyl)-1,3-diphenyl-1,3-diaza-2λ3-phospholidine with nitrile imines

The multistep reactions of 2-(2-chloro-4,5-dihydro-3-furyl)-1,3-diphenyl-1,3-diaza-2³-phospholidine with nitrile imines afforded phosphorus-containing spiro compounds of a new type, viz., 6,8-disubstituted 9-oxo-10-(2-chloroethyl)-1,4-diphenyl-1,4,7,8-tetraaza-5-phosphaspiro[4.5]-deca-6,10-dienes.     

Intramolecular cyclization of 1,3-diamino-2-hydroxypropan-N,N,N´,N´-tetrakis(methylphosphonic acid) upon phosphonomethylation of 1,3-diaminopropan-2-ol

Phosphonomethylation of 1,3-diaminopropan-2-ol affords the mixture of 1,3-diamino-2-hydroxypropan-N,N,N´,N´-tetrakis(methylphosphonic acid) (1) with its cyclic ether, viz., [(6-[bis(phosphonomethyl)amino]methyl-2-hydroxy-2-oxido-1,4,2-oxazaphosphinan-4-yl)methyl]phosphonic acid (2), but not 1, as assumed earlier.

     

Unexpected Microwave Reaction of 1,3‐Disubstituted Imidazolium Salts: A Novel Synthesis of 1,3‐Disubstituted Imidazole‐2‐thiones

Microwave‐promoted reaction of 1,3‐disubstituted imidazolium salts with potassium thioacetate or potassium thiocyanate under solvent‐free conditions provided a rapid and efficient synthesis of 1,3‐disubstituted imidazole‐2‐thiones.     

Kinetic Studies of Electrochemical Oxidation of 1,3-Benzenedithiol

The electrochemical oxidation of 1, 3-benzenedithiol was investigated in a 0. 100 mol/L tetrabutylammonium perchlorate/acetonitrile electrolyte. The electrochemical techniques used were potential sweep, bulk electrolysis, rotating disc and the potential step method. The combination of the techniques yielded the number of electrons transferred per molecule, the reaction order, the transfer coefficient, the diffusion coefficient and concentration of dithiol anions, the standard heterogeneous rate constant as well as the formal potential and equilibrium constant of the preceeding dissociation reaction. This paper also illustrates the methods for studying the electrode kinetics of reactions which (a) involve a chemical reaction preceeding the electron-transfer process, (b) have insoluble polymer products, and (c) are totally irreversible.     

IR Study of p–π Conjugation in 2-Substituted 4-Methylene-1,3-dioxolanes and 4-Methyl-1,3-dioxoles

Selected group frequencies of the IR spectra of a number of 2-substituted 4-methylene-1,3-dioxolanes (a) and their endocyclic isomers, 2-substituted 4-methyl-1,3-dioxoles (b), have been studied to establish their usefulness as a measure of the strength of p– conjugation in the O—C=C moieties of the title compounds. In the exo compounds (a), the C=C stretching frequencies C=C and the in-phase, out-of-plane bending (wagging) frequencies CH₂ w of the =CH₂ group were found to be linearly related, besides to each other, also to the electron-donating character of the substituents and the ¹³C NMR chemical shift of the C atom of the exocyclic CH₂ group. This suggests that the two IR group frequencies of the exo isomers are linearly related to the strength of p– conjugation in the O—C=C moiety. The C=C stretching absorption of the exo compounds in the 1600–1700 cm^–1 region appeared as a doublet, shown to arise from Fermi resonance of the C=C fundamental with the CH₂ w overtone. The C=C frequencies of the endo compounds support some previous findings of an unexpected strength of p– conjugation in the 2-alkoxy derivatives. Finally, DFT calculations at the B3LYP/6-31G* level of theory are shown to give accurate predictions of the effect of 2-substituents on the group frequencies.     

Synthesis of 1,3-diphenyl-6-alkyl/aryl-substituted fulvene chromophores: observation of π-π interactions in a 6-pyrene-substituted 1,3-diphenylfulvene

The synthesis, structural, and electronic properties of nine 1,3-diphenyl-6-alkyl/aryl substituted pentafulvenes were studied. Pyrene ring π-π interactions were revealed from analysis of the experimental crystal packing of 1,3-diphenyl-6-(1-pyrene)fulvene and supporting DFT calculations. Photophysical properties derived from UV-vis and fluorescence emission measurements demonstrated tunable and low HOMO-LUMO band gaps for the series. The presented results point to a model synthetic approach for incorporation of extended π systems and donor-π-acceptor groups for fulvene-based electronic materials.