Mass spectrometry of pyrrolo [2, 3- b] pyrazines and pyrazino [2, 3- b]indole

The first mass spectra of pyrrolo [2, 3-b] pyrazine and some of its derivatives and of pyrazino [2, 3-b] indole are reported and compared with those of related compounds. Differences between the spectra of some aryl substituted derivatives are described and discussed.     

Recherches dans la série des cyclitols XLVI. Actions de diazoalcanes sur la pentahydroxy-2,4,6/3,5-cyclohexanone et sur son dérivé penta-O-acétylé II. Etude de pentahydroxy-alkyl-C-cycloheptanones

On treatment with higher diazoalkanes, 2,4,6/3,5-penta-acetoxy-cyclohexanone (penta-O-acetyl-myo-inosose-2 or -scyllo-inosose) afforded by ring expansion all-trans-penta-acetoxy-C-alkyl-cycloheptanones, which by deacylation were converted to hemiacetals. The reactions with diazoalkanes of the penta-acetoxy-inosose in the presence of aluminium chloride and of the free inosose in water solution have also been studied. The structure, the configuration, and, in some cases, the conformation of the new compounds have been established and some of their reactions have been investigated. The mechanisms of formation of the ring expansion products and of the concomitant spiro-epoxides have been discussed.     

Enthalpies and entropies of fusion of some substituted dipeptides

Enthalpies and temperatures of fusion or transition for four substituted dipeptides (Nacetylamides of glycyl-L-alanine (NAGAA),L-alanyl-L-alanine (NAA₂A),L-prolyl-glycine (NAPGA) andL-leucyl-L-proline monohydrate (NALPA·H₂O)) were determined by differential scanning calorimetry and the entropies of fusion derived. The results obtained have been compared with those of the corresponding substituted aminoacids and some of their racemic crystalline mixtures. The enthalpies and entropies of fusion of some substituted aminoacids have been redetermined. The results are discussed in comparison with crystal structural data, which has been reported in the literature or determined recently by some of the authors. Rationalization of the fusion parameters was attempted mainly on the basis of the number of intramolecular hydrogen bonds and the packing densities in the crystals.This work was carried out with the financial support from the Italian C.N.R. (Rome) and from the Ministry of University and Scientific and Technological Research.     

Research on heterocyclic compounds. XXI. Synthesis of imidazo[2,1-b]benzothiazole and imidazo[2,1-b]thiazole derivatives

The reaction of some 2-aminobenzothiazoles and 2-aminothiazoles with ethyl 3-bromo-4-oxopentanoate was investigated with the aim to obtain the corresponding imidazo[2,1-b]benzothiazole and imidazo[2,1-b]-thiazole derivatives, respectively. In some cases, two unexpected side products were obtained together with the required compound and their structures were elucidated: e.g., 2-aminobenzothiazole reacted with ethyl 3-bromo-4-oxopentanoate to give ethyl 2-methylimidazo[2,1-b]benzothiazole-3-acetate together with ethyl imi-dazo[2,1-b]benzothiazole-2-propionate and ethyl 3-(benzothiazol-2-yl)amino-4-oxopentanoate.     

Stereochemical studies. Part 67. Saturated heterocycles. Part 52. The mass spectra of some condensed skeleton 1,3-oxazin-4-one derivatives

The mass spectrometric behaviour of twenty saturated heterocyclic compounds with a 1,3-oxazin-4-one moiety fused with cis or trans anellation to a cycloalkane ring (C₅-C₈) was studied. The roles of the C-2 and N-3 substituent(s) were found to be characteristic, while the size of the cycloalkane ring seemed to be unimportant. Some fragmentation processes involving breakdown of the oxazinone ring of the cis or trans isomers displayed significant stereoselectivity. A striking new decomposition process involving significant chlorine elimination from the molecular ion of some 2-p-chlorophenyl derivatives was observed and was studied in some detail.     

The effect of reaction conditions on the chain end structure and functionality during dehydrochlorination of tert-chlorinetelechelic polyisobutylene by potassium tert-butoxide

Dehydrochlorination of tert-chlorine-telechelic polyisobutylene with potassium tert-butoxide in refluxing tetrahydrofuran is quantitative after 22 h, but results in ca. 3% endo olefin chain ends which are not reactive in some subsequent functionalization reactions. The formation of these undesired structures is most likely due to simultaneous thermally induced HCl loss. Lower temperatures and longer reaction times led to exclusive formation of external double bonds in some cases but to incomplete dehydrochlorination.     

Condensed 1,2,4-triazines. Synthesis and reactions of some condensed benzo[e]as-triazines

2-o-Chlorophenyl-2H-naphtho[1,2-d]v-triazole-4,5-quinone condenses with semicarbazide and some of its derivatives at the 4 position and the products cyclize into the corresponding 1,2,4-triazines. Reactions of these triazines with some reagents are described.     

Arenesulfonylheterocycles (I): Synthesis and reactions of 2‐benzenesulfonyl‐4,5‐dichloropyridazin‐3‐ones with amines

The direct sulfonylation of 4,5‐dichloropyridazin‐3‐ones with some benzenesulfonyl chlorides in the presence of base in tetrahydrofuran gave only the corresponding N‐sulfonylated product. The reaction of 2‐benzenesulfonyl‐4,5‐dichloropyridazin‐3‐ones with some aliphatic amines under neutral conditions afforded 5‐alkylamino‐2‐benzenesulfonyl‐4‐chloropyridazin‐3‐ones and/or the corresponding N‐alkyl‐benzenesulfonamides.     

Regioselective Synthesis of Fatty Acid Esters of Glycosides Containing Cis‐diol and Biological Test against Bacterial Staphylococcus aureus and Salmonella agona

Regioselectivity of glycoside containing cis‐diol esterification with fatty acid using dibutyltin dimethoxide as stannylating agent was probed, the results showed the equatorial position of cis‐diol has some advantage of being acylated, although the orientation of adjacent groups could affected the regioselectivity. The glycoside fatty acid esters were regioselectively synthesized on optimized condition with this stannyl method, the biological tests against bacterial as Staphylococcus aureus and Salmonella agona were carried out with these fatty acid esters, the testing results showed that glycoside esters with 12 or 14 carbon long chain fatty acid have some obvious inhibition against Staphylococcus aureus.     

Antioxidant activity of some N-heterocycles derived from 2-(1-(2-oxo-2H-chromen-3-yl)ethylidene) hydrazinecarbothioamide

Efficient and convenient synthesis of coumarin derivatives was accomplished via reactions of 2-(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazinecarbothioamide with some carbon electrophiles, e.g. maleic anhydride, dimethyl acetylenedicarboxylate, 1,2-dichloroethane, 3′-nitro-w-bromoacetophenone, N-(4-acetylphenyl)-2-chloroacetamide, ethyl cyanoacetate/3-chlorobenzaldehyde and acetylacetone to construct some N-heterocycles such as thiazolidine, thiazole, pyrimidine and pyrazolone derivatives. The structures of all synthesized products were substantiated from their analytical and spectral data. The antioxidant activities of the synthesized compounds were examined.     

Synthesis and Bioactivities Evaluation of Novel Anthranilic Diamides Containing N‐(tert‐Butyl)benzohydrazide Moiety as Potent Ryanodine Receptor Activator

Anthranilic diamides have been proven to be a class of efficacious and safe insecticides targeting ryanodine receptors (RyRs) during the last decade. In order to develop innovative scaffolds with high insecticidal activity, two series of N‐pyridylpyrazole derivatives containing N‐(tert‐butyl)benzohydrazide substructures were designed and synthesized. Their insecticidal activities against oriental armyworm (Mythimna separata) and diamondback moth (Plutella xylostella) were evaluated. Preliminary bioassay results revealed that some of the new compounds exhibited good insecticidal activity against the oriental armyworm and diamondback moth. The mode of action of these compounds were verified using calcium‐imaging technique and the results showed that some new compounds could effectively modulate the insect cytosolic Ca²⁺ level, and break the cellular calcium homeostasis, indicating some of these compounds were potent activators of the RyRs.     

New Reactions of Amino-Functionalized 3-Vinyl-1H-indoles and Tetrahydropyridin-4-yl Analogues with Dienophiles

Reactions of 3-[2-(morpholin-4-yl)vinyl]-1H-indole ( 1 ), the 1,2-dihydro-9H-carbazole 2 , as well as the 3-(tetrahydropyridin-4-yl)-1H-indoles 3a and 3b with some carbo- and heterodienophiles are described. The scope and limitations of the synthetic utility of these amino- (or homoamino)-functionalized 3-vinyl-1H-indoles are reported and some MO calculations for the qualitative prediction of their reactivities are presented. The reactions gave rise to substitution products, redox products, Diels-Alder adducts, ene adducts, and Michael-type adducts (Schemes 2 and 3).     

Exact solution of Schrödinger equation for Pseudoharmonic potential

Exact solution of Schr?dinger equation for the pseudoharmonic potential is obtained for an arbitrary angular momentum. The energy eigenvalues and corresponding eigenfunctions are calculated by Nikiforov–Uvarov method. Wavefunctions are expressed in terms of Jacobi polynomials. The energy eigenvalues are calculated numerically for some values of ℓ and n with n ≤ 5 for some diatomic molecules.      

Imidazo[1,2-b]pyridazines: Syntheses and interaction with central and peripheral-type (mitochondrial) benzodiazepine receptors

The fundamental chemistry of pyridazines, the syntheses of substituted irnidazo[1,2-b]pyridazines (1) (and some related compounds) and the interaction of the products with central benzodiazepine receptors (CBR) and peripheral-type (mitochondrial) benzodiazepine receptors (PBR) are described. Some of these imidazo[1,2-b]pyridazines had high selective affinity for the central benzodiazepine receptors and others had high selectivity for the peripheral-type (mitochondrial) benzodiazepine receptors. The results of structure-activity studies and molecular modeling will be reported. In vivo tests of some compounds which interacted strongly with the central benzodiazepine receptors revealed reasonably potent anticonvulsant/anticonflict activity, and some of those which bind selectively to the peripheral-type (mitochondrial) benzodiazepine receptors are being examined as possible radiopharmaceuticals for imaging of tumors (and other disease states).     

Synthesis and Antimicrobial Activity of Novel Furothienoquinoxalines,Pyranothienoquinoxalines and Pyrimidopyranothienoquinoxalines

The reaction of ethyl‐3‐mercaptoquinoxaline‐2‐carboxylate with phenacyl bromide, ethyl chloroacetate, chloroacetonitrile or chloroacetone furnished the corresponding 3‐hydroxy thieno[2,3‐b]quinoxaline. 2‐Cyano‐3‐hydroxythieno[2,3‐b]quinoxaline and 2‐acetyl‐3‐hydroxythieno[2,3‐b]quinoxa line were employed as precursors in the synthesis of some novel furo[2′,3′:4,5]thieno[2,3‐b]quinoxaline, pyrano[2′,3′:4,5]thieno[2,3‐b]quinoxaline and other heterocyclic systems fused with thieno[2,3‐b]quinoxalines. The antibacterial and antifungal activities of some the synthesised compounds were studied.     

Linear free energy ortho-correlations in the thiophene series. Part IX . Kinetics of esterification with diazodiphenylmethane of some 3-, 4-, and 5-substituted thiophene-2-carboxylic acids in methanol

The rate constants for the esterification of some 3-, 4-, and 5-substituted thiophene-2-carboxylic acids with diazodiphenylmethane in methanol at 25° have been measured. The reactivity of some para- and ortho-substituted benzoic acids has also been determined. Logarithmic kinetic constants for ortho-, meta-, and para-like substituted thiophene-2-carboxylic acids furnish an excellent linear free energy relationship when plotted versus Δpk_a (β 0.89, r 0.989, C.L. > 99.9%, n 18, i 0.04), thus confirming the peculiar behaviour of five-membered ring derivatives. The correlation with σ^H values offers an additional proof of the hyper-ortho character of the 2,3-relation in thiophene derivatives. para- and ortho-Substituted benzoic acids show the usual behaviour of six-membered ring derivatives.     

Photochimie d'hétérocycles azotés. IV. Transposition de type photo-fries des N-acétyl benzimidazolones

The photolysis of benzene or alcoholic solutions of N-acetyl-and N,N-diacetylbenzimidazolones gave mixtures of ortho- and para-rearrangements products accompanied to some extent with de-N-acylation. The different products have been identified by means of nmr, mass spectrometry and unambiguous synthesis.     

Facile and expedient synthesis and anti-proliferative activity of diversely pyrrolones bearing 1,3-diphenylpyrazole moiety

Abstract

A series of some pyrrolone derivatives were synthesized from the acid hydrazide, derived from a pyrazolyl-2(3H)-furanone, through treating with some carbonyl reagents such as 1-phenyl-3-(thiophen-2-yl)-1H-pyrazole-4-carbaldehyde, formic acid, lauroyl chloride, succinoyl chloride, propionic anhydride, as well as, ethoxymethylene malononitrile. All compounds were obtained in good yields and characterized by their microanalytical and spectral data. The synthesized products were evaluated for their in vitro antitumor activity against two human carcinoma cell lines (HCT-116 and MCF7) using doxorubicin as a reference drug by MTT assay. The results revealed that some compounds exhibited significant potency. Noteworthy, the N-propionyl hydrazide derivative was the most potent against both cell lines.     

Can be Azo Dyes Obtained by Grinding under Solvent‐Free Conditions?

The solid‐solid reactions of some electron‐donors with sulfanilic acid in the presence of solid sodium nitrite afford azo dyes by self‐catalyzed diazotization of sulfanilic acid (2) under solvent‐free conditions with moderate yields. Also the reactions of some electron‐donors with diazotization of o‐nitroaniline (5), m‐nitroaniline (6) and p‐nitroaniline (7) in the presence of solid sodium nitrite catalyzed by p‐toluenesulfonic acid (PTSA) afford azo dyes under solvent‐free conditions in good yields. This new method totally avoids the use of acids, alkalies, and toxic and/or expensive solvents in diazotization and diazo coupling reactions.     

C-Alkylation of α-acylamino ketones. A versatile synthesis of α-alkyl α-amino ketones

C-Alkylation of some α-acylamino ketones were achieved with alkyl halides by means of sodium ethoxide in ethanol. The present paper deals with the C-alkylation of N,N-diformylamino ketones and the difference in stability of the amide group.