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The electrophilic halogenation and chalcogenation (sulfenylation and selenenylation) of endo and exo isomers of ethyl 2-azabicyclo[2.2.1]hept-5-ene-3-carboxylates bearing electron-withdrawing substituents at the nitrogen atoms with different reagents were studied. Halogenation of both endo and exo isomers gave exclusively the rearranged products. Chalcogenation of endo isomer resulted in the rearranged products, while chalcogenation of exo isomer afforded the rearranged products and 1,2-trans and 1,2-cis addition products. [ABSTRACT FROM AUTHOR]

Methods for the synthesis of new ditopic organic ligands containing coordinating fragments of two types, terpyridine and thiohydantoin, have been developed. The complex formation reactions of the synthesized ligands with copper(II) chloride were studied. As a result, two types of coordination compounds were isolated and characterized by electron spectroscopy, elemental analysis, and cyclic voltammetry: copper(I,II) bis-ligand tetranuclear mixed-valent complexes and a monoligand binuclear complex containing two copper(II) ions. The cytotoxic activity of the obtained coordination compounds with respect to the MCF7, A549, and HEK293 cell lines was studied. [ABSTRACT FROM AUTHOR]

A method for the synthesis of 4-methyl-2-oxo-9-phenyl-2H-furo[2,3-h]chromene-8-carboxylic acid amides combining in the structure the angelicin core with heterocyclic fragments at the amide nitrogen atom was developed. The cytotoxic activity of the obtained amides against the MCF7 (breast adenocarcinoma), A549 (non-small cell lung cancer), VA-13 (embryonic lung fibroblast cells) and HEK293T (embryonic kidney cells) cell lines was studied. In contrast to the previously described highly toxic angelicin derivatives with aryl- and hetarylcarbonyl substituents at position 8, the synthesized amides demonstrated in in vitro experiments in these cell lines the IC50abs values ranging within 2–100 µmol L−1. The cytotoxicity and selectivity of the action of this group of derivatives were found to be significantly affected by the substituent at position 5′ of the angelicin moiety. [ABSTRACT FROM AUTHOR]

A method for the synthesis of a conjugate of 4-substituted phenylterpyridine and lipoic acid, containing a triethylene glycol linker group between the terpyridine and sulfur-containing fragments, has been developed. A coordination compound of the resulting terpyridine with Rh(III) was obtained. Cyclic voltammetry was used to explore the ability of the synthesized ligand and its rhodium complex to be chemisorbed on the surface of gold electrodes to form an Au–S bond. [ABSTRACT FROM AUTHOR]

A convenient one-pot synthesis of α-bromoacrylic acid esters followed by their conversion into α-bromo-substituted β-amino acid esters via Michael addition with secondary cyclic amines is proposed. Among the amines, morpholine turned most suitable. [ABSTRACT FROM AUTHOR]

Three groups of bile acid derivatives with acetylenic moieties, such as propargyl, hex-5-ynoyl, and 4,7,10,13-tetraoxahexadec-15-ynoyl ones, were obtained. The cytotoxic activity of the synthesized compounds against hepatocellular carcinoma (HepG2, Huh7), prostate cancer (PC3), and human embryonic kidney (HEK293) cell lines was studied. The parameters enabling estimation of the total lipophilicity of the synthesized bile acid derivatives (logP, TPSA) were calculated. The correlation between the cytotoxic activity and hydrophilic-lipophilic balance of the synthesized compounds was determined. A physicochemical mechanism for the cytotoxic action of bile acid derivatives is proposed. [ABSTRACT FROM AUTHOR]

A convenient procedure has been proposed for the isolation of R and S enantiomers of 1-(2,4-di-methoxyphenyl)ethan-1-amine from the racemate using di-O-benzoyltartaric acids as chiral auxiliaries. The pure enantiomers were converted into the corresponding chiral thioureas and 2-thiohydantoins by reaction with ethyl 2-isothiocyanatoacetate. [ABSTRACT FROM AUTHOR]

We synthesized substituted phenylterpyridines containing one or two terminal disulfide groups and triazole-containing fragments in the linker between the terpyridine and sulfur-containing functional groups, as well as coordination compounds of the obtained terpyridines with RhIII. The possibility of the ligands and complexes under study to be chemisorbed on the surface of gold electrodes with the formation of an Au-S bond was shown. [ABSTRACT FROM AUTHOR]

A method for the preparation of new organic ligands combining in their structure a 2-(pyridin-2-yl)benzothiazole moiety capable of coordinating metal iones and a thioacetate group, which makes it possible to adsorb the obtained compounds on a gold surface, has been developed. Using cyclic voltammetry, the possibility of chemisorption of the obtained compounds on the surface of gold electrodes and obtaining complexes of adsorbed ligands with CuCl2 has been shown. [ABSTRACT FROM AUTHOR]

Synthesis of new bis(seleno-imidazolone) derivatives bearing the alkyl and aryl moieties at the N(1) atom of the five-membered ring was developed. Cytotoxicity of the synthesized compounds against A549, VA-13, MCF-7, and HEK293T cell lines was evaluated. [ABSTRACT FROM AUTHOR]

The reactions of diaryl-, aryl-, and alkyl–arylcyclopropanes with ethyl nitrite in the presence of sulfur trioxide and sulfur trioxide dioxane complex, as well as the reactions of 1-alkyl-2-arylcyclopropanes with NOBF4 were studied. It was found that the attack of the nitrosonium cation, accompanied by the formation of a benzyl carbocation, leads to the formation of isoxazolines. The introduction of bulky alkyl substituents into the cyclopropane ring changes the regioselectivity of nitrosation, favoring the attack of the electrophilic particle on the benzyl position and leading to the competitive formation of an alkyl carbocation. Depending on the structure of the alkyl substituent, both products of intramolecular heterocyclization accompanied by skeletal rearrangements and products formed with the participation of an external nucleophile are formed. [ABSTRACT FROM AUTHOR]

New ditopic organic ligands with (pyridylmethylidene)imidazolone and pyridylbenzothi-azole moieties were synthesized by Cu-catalyzed azide-alkyne cycloaddition of 6-(prop-2-yn-1yloxy)-2-(pyridin-2-yl)benzothiazoleto3-azidoalkyl-5-[(Z-(pyridin-2-yl)methylidene]-2-(methylthio)dihydro-4H-imidazol-4-ones. The synthesized ligands (L) react with copper(ii) chloride to give coordination compounds of general formula LCuCl2 with coordination of the copper ion on the pyridylbenzothiazole fragment. [ABSTRACT FROM AUTHOR]

New ligands for targeted delivery to the liver based on glycoconjugated natural triterpenoids are proposed. Simple chemical transformations of starting lupane triterpenes led to betulin or betulinic acid conjugates with N-acetyl-d-galactosamine linked through an isopropenyl fragment of the terpene skeleton. The obtained compounds were non-toxic in vitro to a series of cancer cell lines and normal cells. Molecular docking in silico and surface plasmon resonance spectroscopy revealed a high specificity of the synthesized glycotriterpenoids to the asialogly-coprotein receptor of hepatocytes. [ABSTRACT FROM AUTHOR]

New type dispiroindolinones, dispiroimidazolidine-4,3′-pyrrolidine-2′,3″-indolinones unsubstituted at position 4′ of the central pyrrolidine ring, were synthesized by the 1,3-dipolar cycloaddition of azomethine ylides, generated from N-alkyl-substituted amino acids and isatines, to 5-methylidene-substituted 3-phenylhydantoin. [ABSTRACT FROM AUTHOR]

It was demonstrated that nitrosylsulfuric acid can be successfully used as a tandem nitrosating and oxidizing agent in the synthesis of 3,5-diarylisoxazoles from 1,2-diarylcyclopropanes. The reaction proceeds highly regioselectively in the case of symmetric diarylcyclopropanes. The mixtures of regioisomeric 3,5-diarylisoxazoles were obtained from non-symmetric 1,2-diarylcyclopropanes. [ABSTRACT FROM AUTHOR]

A convenient method is proposed for the synthesis of N-unsubstituted spiroxindoles with different heterocyclic moieties (2-thiohydantoin, hydantoin, and thiazolidine) by the regio-selective 1,3-dipolar cycloaddition of azomethine ylides, generated from isatins and sarcosine, to arylidene derivatives of corresponding heterocycles. The cytotoxicity of compounds was tested by the MTT method against MCF7, A549, HEK, and VA13 cell lines and compared with the anticancer drug Nutlin-3a. The best bioactivity was observed for hydantoin-based dispiroindolinones, the most cytotoxic compound demonstrated selectivity against A549 lung cancer cells with an IC50 value of 6.6±1.6 μmol L−1. [ABSTRACT FROM AUTHOR]

A method for synthesizing CuII coordination compounds with 2-hetaryl-substituted benzothiazoles was developed. The reactions of 2-amino-5-methoxythiophenol, 2-pyridyl- or 2(4)-imidazolylcarbaldehydes, and copper(ii) perchlorate in refluxing ethanol yield L2Cu(ClO4)2 or L3Cu(ClO4)2 complexes. According to the cyclic voltammetry data, the obtained copper coordination compounds can catalyze dismutation of superoxide anion. [ABSTRACT FROM AUTHOR]

An approach for the synthesis of new organic ligands combining in their structure pyridine, benzothiazole, and polyethylene glycol fragments was developed, proceeding from 6-hydroxy-2-(pyridin-2-yl)benzothiazole and mono- or ditosyl-substituted polyethylene glycols. The ligand 2-(2-{[2-(pyridin-2-yl)benzothiazol-6-yl]oxy}ethoxy)ethanol (L) in the reaction with Cu(ClO4)2•6 H2O and CuCl2•2 H2O formed coordination compounds of the composition L2Cu(ClO4)2•7 H2O and LCuCl2•0.5 H2O, respectively. [ABSTRACT FROM AUTHOR]

A method has been developed for the preparation of a new type of dispiro derivative, 5''-bromo-2-[(4-chlorophenyl)sulfanyl]-1'-methyl-1,4'-diphenyldispiro[imidazole-4,3'-pyrrolidine-2',3''-indoline]-2'',5(1H)-dione, starting from 2-thiohydantoin and using a 1,3-dipolar cycloaddition reaction. The configuration of the target dispiro derivative was unambiguously established by physicochemical methods. [ABSTRACT FROM AUTHOR]

Regioselective synthesis of new dispiro indolinones combining both an indolinone and an oxazolone fragment in their structure comprised the 1,3-dipolar cycloaddition of azomethine ylides, generated in situ from isatin and sarcosine, at 2-aryl-5-arylmethylidene-substituted 1,3-oxazol-5(4H)-ones. When ortho and para halogen atoms were present in the aromatic substituents of the starting oxazolones, complex mixtures containing large amounts of oxazoline ring opening products and their dispiro derivatives were formed. The cytotoxicity of compounds was tested by MTT on LNCaP, PC3, HCT116, MCF7, A549, HEK, and VA13 cell lines. The compound possessing the best cytotoxicity revealed the IC50 = 1.08±0.96 μM towards the p53- expressing LNCaP cells and lower activity (IC50 = 3.21±1.45 μM) towards the non-expressing p53 protein PC3 cells, however, it has proved inactive towards the HCT cells, both expressing (HCТ+/+) and non-expressing (HCT-/-) p53. [ABSTRACT FROM AUTHOR]

By six examples, it was demonstrated that nitrosylsulfuric acid can be successfully used for oxidation of 3,5-diaryl-4,5-dihydroisoxazoles to the corresponding 3,5-diarylisoxazoles. If the starting isoxazolines contain the aromatic substituents activated towards electrophilic substitution, nitration of both newly formed isoxazole and substituted benzene rings occurred. [ABSTRACT FROM AUTHOR]

Electrochemical investigation of 4(6)-dihalomethyl-4(6)-methylcyclohexa-2,5(2,4)-dien-1-ones using cyclic voltammetry (CVA) and rotating disc electrode (RDE) methods has been performed. The reductive dehalogenation of cyclohexa-2,5(2,4)-dien-1-ones having a dihalomethyl substituent at the tertiary carbon atom was shown to proceed as a two-electron reductive elimination of the geminal halogen atoms with the intermediate formation of carbene and subsequent rearrangement of cyclohexadienone with the ring expansion to the corresponding 4- or 2-methylcyclohepta-2,4,6-trien-1-one. [ABSTRACT FROM AUTHOR]

Published data on the structure, stereochemistry, and biological activity of natural cyclic polypeptides containing fragments of β-amino acids are reviewed, and an attempt is made to relate the structure to the biological activity. [ABSTRACT FROM AUTHOR]

Reactions of potassium dihaloiodates with arylcyclopropanes and polycyclic compounds containing a cyclopropane fragment characterized by different degrees of strain lead to formation of mixed 1,3-halogenation products. If iodohalogenation should give rise to products having a iodine atom in the benzylic position, 1,3-dichloro or 1,3-dibromo derivatives are formed. Iodohalogenation of exo-tricyclo[3.2.1.0]octane is stereoselective and is accompanied by Wagner-Meerwein rearrangement. [ABSTRACT FROM AUTHOR]

Organic ligands containing terpyridine and disulfide groupings linked between one another by a bonding -O(CH) ( n = 6, 12) fragment have been synthesized. Gold nanoparticles of mean size 1.8 nm modified with the indicated ligand were obtained by the method of Brust. By methods of electron spectroscopy and cyclic voltamperometry, the possibility of forming of coordinated compounds on the surface of gold nanoparticles modified by a terpyridine ligand, on interaction with Cu(MeCN)ClO has been shown. The obtained nanoparticles catalyze the oxidation of 2,4-di-tert-butylphenol into 3,3',5,5'-tetra(tert-butyl)biphenyl-2,2'-diol. [ABSTRACT FROM AUTHOR]

The electrophilic sulfenylation of a series of indoles and pyrroles with arylsulfenamides in the presence of phophorus(V) oxohalide has been studied. It has been shown that arylsulfenylation of indoles led to products with substitution at position 3, while in the case of pyrrole it occurred at position 2. [ABSTRACT FROM AUTHOR]

Nitrosonium hexachlorostannate (NO)[SnCl] was synthesized by the reaction of NOCl and SnCl in CHCl. According to the single-crystal X-ray diffraction analysis data, the structure of (NO)[SnCl] consists of cations NO and octahedral anions [SnCl] arranged as ions in antifluorite. Isoxazolines were synthesized by the reactions of (NO)[SnCl] with arylcyclopropanes containing donor substituents in the aromatic ring. [ABSTRACT FROM AUTHOR]

new method for the synthesis of thiocyanato- and isothiocyanatoalkyl phenyl sulfides by the reaction of unsaturated compounds with ethyl benzenesulfenate and trimethylsilyl isothiocyanate has been suggested. Regio- and stereoselectivity of the reaction was studied, having taken alkenes, dienes, and alkynes as examples. [ABSTRACT FROM AUTHOR]

Using the method of cyclic voltammetry the possibility of formation of the Pd(II) complex with triarylphosphine ligand on the gold electrode surface is shown resulting from the following sequence of reactions: (1) formation of the self-organized monolayer (SOM) of di(11-mercaptoundecyl)disulfide on the Au surface; (2) esterification of terminal hydroxy groups of the formed SOM with diphenyl(p-carboxyphenyl) phosphine; (3) formation of the complex compound fixed on the surface by treatment of the modified electrode with solution of PdCl2 in CH3CN. The possibility of electrocatalytic reduction of iodobenzene on the gold electrode with participation of the obtained Pd(II) complex is demonstrated. [ABSTRACT FROM AUTHOR]

A series of cyclic and acyclic diamido-bis-sulfide ligands were synthesized by N-acylation of 1,2-bis(2-aminophenylthio)ethane and 1,4-bis(2-aminophenylthio)butane with acetic, malonic, and 3,3′-dithiodipropionic acid chlorides or esters. The complexation of obtained ligands with CuII, NiII, and CoII salts in solution and on the gold electrode surface was studied. The formation of complexes of these ligands with copper(II) chloride in DMF is irreversible and accompanied by deprotonation of the amide nitrogen atoms. [ABSTRACT FROM AUTHOR]

Cu(ClO4)2·6H2O was shown to react with 2,2′-[propane-1,3-diylbis(thio-2-phenylnemethylidene]-bis(3-pyridylamine) ( I) or (5Z)-2-ethoxycarbonylmethyl-(2-pyridylmethylidene)-3,5-dihydro-4 H-imidazol-4-one ( II) in the presence of CH3CN with the reduction of copper(II) to copper(I) and the formation of the tetrahedral complex CuI(CH3CN)4ClO4 ( III). In the course of the reaction the organic ligands I and II were oxidized to the corresponding sulfoxides. [ABSTRACT FROM AUTHOR]

Tetradentate N4-type organic ligands containing two 5-(2-pyridylmethylidene)-2-thio-3,5-dihydro-4 H-imidazol-4-one fragments linked by two-, four-, or six-carbon polymethylene bridges between the sulfur atoms were synthesized. Mono- and dinuclear complexes of these ligands with copper(II) chloride, as well as with copper(I) and copper(II) perchlorates, were prepared. The structure of the coordination compound (5 Z,5′ Z)-2,2′-(butane-1,2-diyl-disulfanyldiyl)bis-5-(2-pyridylmethylidene)-3-phenyl-3,5-dihydro-4 H-imidazol-4-one with copper(I) perchlorate was established by X-ray diffraction. The copper atom in this complex is in a distorted tetrahedral coordination formed by four nitrogen atoms of two imidazole and two pyridine rings. The perchlorate anion is located in the outer sphere of the complex and is not involved in the coordination with the copper ion. The electrochemical study of the ligands and the complexes was carried out by cyclic voltammetry and rotating disk electrode voltammetry. The initial reduction of the complexes under study occurs at the metal atom. The length of the polymethylene bridge in the ligand has only a slight effect on the redox properties of the ligands and the complexes. [ABSTRACT FROM AUTHOR]

A new procedure was proposed for activation of areneselenenamides with phosphorus(V) and sulfur(IV) oxyhalides. According to the 1H, 13C, and 31P NMR data, areneselenenamide reacts with phosphorus oxyhalide to form intermediate adduct in which the phosphorus atom is coordinated at the selenium. Areneselenenamides activated by phosphorus(V) oxyhalides react with alkenes (norbornene and norbornadiene) with high trans-stereoselectivity. Their reactions with terminal olefins are regioselective, and they lead to preferential formation of the corresponding Markovnikov adducts. [ABSTRACT FROM AUTHOR]

Electrochemical behavior of 4-halomethyl-4-methylcyclohexa-2,5-dien-1-ones and 2,6-dibromo-4,4-dimethylcyclohexa-2,5-dien-1-one was studied. Reductive dehalogenation of cyclohexa-2,5-dien-1-ones having a halogen atom at the neopentyl-like carbon atom gives the corresponding carbanion which undergoes anionic cyclopropyl-allyl rearrangement with subsequent addition of proton to form 3,4-dimethylphenol. [ABSTRACT FROM AUTHOR]

The reaction of phenylcyclopropanes substituted in the three-membered ring with nitrosyl chloride activated with sulfur(IV, VI) oxides provided in good yield substituted 5-phenylisoxazolines as a mixture of structural isomers. [ABSTRACT FROM AUTHOR]

2-( endo-7-Hydroxybicyclo[3.3.1]non- exo-3-ylmethyl)propane-1,3-diol was synthesized in seven steps starting from endo-7-hydroxybicyclo[3.3.1]nonane- exo-3-carboxylic acid. The title compound attracts interest as intermediate product for the synthesis of potential tubulin ligands. [ABSTRACT FROM AUTHOR]

Arylcyclopropanes react with nitrosyl chloride activated by sulfur(VI) oxide to give the corresponding 5-aryl-4,5-dihydro-1,2-oxazoles in quantitative yields. The complex NOC1·2SO3 is a highly efficient nitrosating agent which makes it possible to involve in the process arylcyclopropanes having both donor and acceptor substituents in the aromatic ring. [ABSTRACT FROM AUTHOR]

The ring opening in the 1-benzyl-5,7-dimethyl-6-oxo-1-azonia-3-azaadamantane chloride under the treatment with excess aqueous alkali led to a stereoselective formation of anti-1,5-dimethyl-7-benzyl-3-formyl-3,7-diazabicyclo[3.3.1]nonan-9-ol whose structure was established by means of X-ray diffraction analysis and NMR spectroscopy. A reaction mechanism was suggested involving an intramolecular redox hydride transfer. [ABSTRACT FROM AUTHOR]

Reactions of alkynelsufenamides with olefins (such as cyclohexene, norbornene, 1-hexene, 1-octene, allylbenzene, and styrene) in the presence of phosphoryl halides (POCl3, POBr3) afforded 70–95% of β-halo-substituted alkyl alkynyl sulfides. The reactions with cyclohexene and norbornene are characterized by trans stereoselectivity. Alkynylsulfenylation of terminal alkyl- and benzylacetylenes occurs in a regioselective fashion with predominant formation of the corresponding anti-Markownikoff adducts, while the addition to styrene yields halogen-containing sulfides according to the Markownikoff rule. [ABSTRACT FROM AUTHOR]

The review describes the syntheses and probable biologically active conformations of taxol, a natural antitumor agent, and systematizes published data on the structure-activity relations in the series of taxol analogs. [ABSTRACT FROM AUTHOR]

According to the X-ray diffraction data, the major isomer of 1-(N-benzoyl-β-alanyloxy)-4-benzoyl-oxyadamantane obtained by esterification of β-alanine with 5-hydroxyadamantan-2-one and subsequent benzoylation has trans configuration. The trans–cis isomer ratio is 2:1. A similar isomer ratio was found for 1-(N-benzoylphenylisoseryloxy)-4-benzoyloxyadamantane synthesized by an analogous method. [ABSTRACT FROM AUTHOR]

Some previously unknown acetamino derivatives were synthesized by the Ritter reaction from ketones of the adamantane and oxahomoadamantane series. The presence of a hydroxy group as substituent in adamantan-2-one gives rise to formation of acetamino derivatives as products of replacement of the hydroxy group and transformation of the carbonyl group. [ABSTRACT FROM AUTHOR]

The direction of trifluoroacetylation with trifluoroacetic anhydride of 3,4-dihydropyrrolo[1,2-a]pyrazines containing an alkyl or aralkyl substituent in position 1 depends on both the structure of the 3,4-dihydropyrrolo[1,2-a]pyrazine starting materials and on the ratio of reagent:substrate. It may lead to both mono- and disubstituted products. Trifluoroacetylation of 1-methyl-3,4-dihydropyrrolo[1,2-a]pyrazines occurs at the methyl group. Acetylation of 3,4-dihydropyrrolo[1,2-a]pyrazines leads only to N-acetyl-substituted reaction products. [ABSTRACT FROM AUTHOR]

Treatment of 1,5- and 1,3-dicarbonyl derivatives of 2,2-dimethyltetrahydropyran with a series of binucleophiles gave condensed pyranopyrazole, pyranothiopyrimidine, pyranoisoxazole, and pyranopyridine systems. [ABSTRACT FROM AUTHOR]

A series of previously unreported aldehydes has been prepared by the formylation reaction of dipyrrolo[1,2-a;2':,1'-c]pyrazines and their 5,6-dihydro analogs by DMF and phosphorus oxychloride. [ABSTRACT FROM AUTHOR]

We have studied the behavior of asymmetrically substituted dipyrrolo[1,2-a;2',1'-c]pyrazines and their 5,6-dihydro analogs under phosphorylation reaction conditions. [ABSTRACT FROM AUTHOR]

Arylcyclopropanes readily react with nitrosyl chloride in liquid sulfur dioxide to give the corresponding 5-aryl-4,5-dihydroisoxazoles in good yield. The reaction is most selective at -40 to -50°C; at higher temperature, the contribution of side processes becomes appreciable. The complete conversion of arylcyclopropanes containing donor substituents is attained with the use of 1.5 equiv of nitrosyl chloride, while the rate of the transformation of compounds with nonactivated aromatic rings considerably increases on raising the molar ratio NOCl-arylcyclopropane. [ABSTRACT FROM AUTHOR]

The reactions of 2-phenylpropanal with ethyl hydrogen malonate and benzylamine (or benzylammonium acetate) and of ethyl 4-phenyl-2-pentenoate with benzylamine take different pathways, depending on the conditions. [ABSTRACT FROM AUTHOR]

Electrophilic sulfenylation of cyclic and open-chain conjugated dienes effected by a system arylsulfenamide-phosphorus oxyhalide was investigated. The initially formed adducts of 1,2-halosulfenylation in the course of the reaction and also at storage and chromatograqphic purification on silica gel undergo quantitative isomerization into a mixture of stereoisomeric products of 1,4-addition. The effect of halogen nature and the character of substituents in the benzene ring of arenesulfenamide on the addition rate of sulfenamides activated by phosphorus oxyhalides to open-chain and cyclic conjugated dienes and isomerization rate of the arising 1,2-adducts was examined. [ABSTRACT FROM AUTHOR]

Opening of the aziridine ring in 3-bromo-1-alkyl-1-azoniatricyclo[2.2.1.02,6]heptane bromides by the action of various nucleophiles leads to formation of the corresponding 6-substituted 2-alkyl-2-azabicyclo[2.2.1]heptanes. [ABSTRACT FROM AUTHOR]