Synthesis and cytotoxic activity of derivatives of the <Emphasis Type="Italic">tert</Emphasis>-butyl ester of 7<Emphasis Type="Italic">Z</Emphasis>-acetylmethylene-3-methyl-3-cephem-4-carboxylic acid

The condensation of the acetylmethylene group in the tert-butyl esters of 7Z-acetylmethylene-3-methyl-3-cephem-4-carboxylic acid and 7Z-acetylmethylene-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid and in 7Z-acetylmethylene-3-methylene-1,1-dioxo-3-cephem with arylmethoxyamines and O-alkylation of the tert-butyl ester of 7Z-(2-hydroxyimino)propylidene-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid using substituted benzyl bromides as well as pyridylmethyl chlorides gave arylmethoxyimino and pyridylmethoxyimino derivatives of these compounds in the syn and anti isomeric forms. The Vilsmaier reagent was used to introduce the N,N-dimethylaminomethylene group at C-2 of the cephem system in the tert-butyl esters of 7Z-[2-(arylmethoxyimino)propylidene]-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid. Subsequent transformation of the N,N-dimethylaminomethylene cephems using hydroxylamine led to 3Z-[2-(anti-arylmethoxyimino)propylidene]-tert-butoxycarbonylmethyl-4-(5-methyl-4-isoxazolylsulfonyl)- azetidin-2-ones. Condensation of the acetyl group in the tert-butyl ester of 7Z-acetylmethylene- 3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid with 4-bromophenylhydrazine gave a cephem with a 2-(4-bromophenylhydrazono)propylidene group at C-7. Acylation of the tert-butyl ester of 7Z-(2-hydroxyimino)propylidene-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid by 2-bromobenzoyl chloride gave a cephem with a 2-(2-bromo-benzoyloxyimino)propylidene group at C-7. Biological screening of these products towards to malignant and normal cells in vitro showed that their antitumor activity and cytotoxic selectivity towards to malignant and normal cells depend on the structure and configuration of the arylmethoxyimino and pyridylmethoxyimino groups in the 7-alkylidene substituent as well as on the presence or absence of N,N-dimethylaminomethylene and carboxyl groups, respectively, at C-2 and C-4 of the cephem system.     

Synthesis and anticancer properties of 7α-chloro-3-methyl-1,1-dioxoceph-3-em-4-carboxylic acid esters

The tert-butyl esters of 3-azidomethyl-, 3-isocyanatomethyl-, 3-chloromethyl-, and 3-p-nitrophenylvinyl-7α-chloro-1,1-dioxoceph-3-em-4-carboxylic acid, and also esters of 7α-chloro-3-methyl-1,1-dioxoceph-3-em-4-carboxylic acid, and of 7α-chloro-3-methyl-2-dimethylaminomethylene-1,1-dioxoceph-3-em-4-carboxylic acid have been synthesized. Results of cytotoxic screening of these compounds in relation to cancer and normal cells in vitro are correlated and analyzed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 259–273, February, 2007.     

Synthesis of the (Z) and (E) isomers of 1,2-diaryl-3-methyl-4,5-dioxo-3-pyrrolidinecarboxylic acid esters. Structural assignment by nmr and mass spectroscopy

Reaction of N-benzylideneaniline, 1a , with 3-methyl-2-oxobutanedioic acid diethyl ester, 2a , produced isomeric 3-methyl-4,5-dioxo-1,2-diphenyl-3-pyrrolidinecarboxylic acid ethyl esters, 3a and 3b . The higher melting isomer, 3a , was shown to have the (Z) configuration by nmr spectroscopy. The (Z) and (E) isomers of 3-methyl-4,5-dioxo-1,2-diphenyl-3-pyrrolidinecarboxylic acid methyl esters, 3c and 3d , were prepared from 1a and 3-methyl-2-oxobutanedioic acid dimethyl ester, 2b . The higher melting isomer, 3c , was shown to have the (Z) configuration. Similarly, N-benzylidene-p-toluidine, 1b , reacted with 2a to form (Z) and (E) isomers of 3-methyl-4,5-dioxo-1-(4-methylphenyl)-2-phenyl-3-pyrrolidinecarboxlic acid ethyl esters, 3e and 3f . Assignment of the ¹³C carbonyl carbon nmr chemical shift was made by preparing 2-methyl-3-oxobutanedioic-1-¹³C acid diethyl ester, 4 , and from it the corresponding (Z) and (E) isomers of 3-methyl-4,5-dioxo-1,2-diphenyl-3-pyrrolidinecarboxylic ¹³C acid ester, 5a and 5b . The mass spectra of the (Z) isomers exhibit prominent ions corresponding to the masses of the Schiff bases used to make them, and ions corresponding to the loss of ArNCOCO from the parent ion. The (E) isomers 3b, 3d and 5b exhibit a prominent ion of mass 264; 3f gives mass 278, corresponding to the loss of the carboalkoxy group.     

Reaction of organozinc reagents prepared from bromomalonic acid esters and zinc with 3-aryl-2-cyanopropenoic acid primary amides

Organozinc compounds prepared from bromomalonic acid esters and zinc react with 3-aryl-2-cyanopropenoic acid primary amides giving a single diastereomer of the corresponding 1-R′-4-aryl-2,6-dioxo-5-cyanopiperidine-3-carboxylic acid esters, or 3-R′-6-aryl-2,4-dioxo-5-cyano-3-azabicyclo[3.1.0]hexene-1-carboxylic acid esters.     

Synthesis and structural modification of <Emphasis Type="Italic">tert</Emphasis>-butyl ester of 7α-chloro-2-(N,N-dimethylaminomethylene)-3-methyl-1,1-dioxoceph-3-em-4-carboxylic acid

The reaction of tert-butyl 7α-chloro-and 7-β-chloro-7α-isopropoxy-3-methyl-1,1-dioxoceph-3-em-4-carboxylates with the Vilsmeier reagent was carried out with introduction of N,N-dimethylaminomethylene group at position 2 in the E-and Z-isomeric forms. Prolonged treatment of tert-butyl 7α-chloro-3-methyl-2-(N,N-dimethylaminomethylene)-1,1-dioxoceph-3-em-4-carboxylate with hydroxylamine hydrochloride in acetonitrile at 40–50°C gave tert-butyl 10(S)-chloro-6-methyl-5-oxa-1,1,9-trioxo-1-thia-4,8-diazatricyclo[7,2,0,0^2,6]undecane-7(R)-carboxylate which isomerized into 1-tertbutoxycarbonylmethyl-3α-chloro-4-(5-methylisoxazole-4-sulfonyl)azetidin-2-one. In the case of tertbutyl 7β-chloro-7α-isopropoxy-3-methyl-2-(N,N-dimethylaminomethylen)-1,1-dioxoceph-3-em-4-carboxylate the analogous reaction gave tert-butyl 10β-chloro-(2S,6S,7S,10R,11R)-10α-isopropoxy-6-methyl-5-oxa-1,1,9-trioxo-1-thia-4,8-diazatricyclo[7,2,0,0^2,6]undecane-7(R)-carboxylate, the struc-ture of which was determined by 2D-NOESY two-dimensional spectroscopy. The compounds synthesized showed weak or no cytotoxic activity with respect to monolayers of cancer cells in vitro.     

1,6- and 1,7-naphthyridines. II. Synthesis from acyclic precursors

A number of 8-hydroxy-6-methyl-1,6-naphthyridin-5(6H)-one-7-carboxylic acid alkyl esters 3 and the isomeric 5-hydroxy-7-methyl-1,7-naphthyridin-8(7H)-one-6-carboxylic acid alkyl esters 4 were synthesized from acyclic precursors obtained starting from quinolinic anhydride 5. Thus, methanolysis of 5 afforded the hemiester 6 which treated with oxalyl chloride and sarcosine ethyl ester gave 3-(N-ethoxycarbonylmethyl-N-methylcarbamoyl)pyridine-2-carboxylic acid methyl ester 8. Compound 8 was cyclized to naphthyridines 3a-e with sodium alkoxides. The isomeric naphthyridines 4a-c were obtained by cyclization of the open intermediary 2-(N-ethoxycarbonylmethyl-N-methylcarbamoyl)pyridine-3-carboxylic acid methyl ester 9 obtained by a route that involves treatment of 5 with sarcosine ethyl ester and esterification with diazomethane. Spectroscopic properties (¹H nmr, uv, ir) of compounds 3 and 4 are discussed and confirmed the proposed structures.     

Stereoselective synthesis of highly enantioenriched 3-methyl-2-cyclohexen-1-ones possessing an asymmetric quaternary carbon as C-4 or C-6: a sugar template approach

The 1,4-addition of the enolate generated from α-methylated acetoacetate incorporated at C-4 of methyl 6-deoxy-2,3-di-O-(tert-butyldimethylsilyl)-α-d-glucopyranoside to methyl vinyl ketone, followed by aldol condensation of the resulting 1,4-addition product under two base-mediated conditions, provided 4-O-functionalized d-glucose derivatives with high diastereoselectivity. These products install a 3-methyl-2-cyclohexen-1-one-4- (or -6-) carboxylic acid as the O-4 ester, in which C-4 or C-6 is an asymmetric quaternary carbon. Removal of the sugar template from those aldol condensation products provided synthetically useful 3,6-dimethyl-2-cyclohexen-1-one-6-carboxylic acid and 3,4-dimethyl-2-cyclohexen-1-one-4-carboxylic acid derivatives both in high enantioenriched forms.     

Synthesis and antibacterial activity of 1-(substituted-benzyl)-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acids and their 6,8-difluoro analogs

Alkylation of 6,7-difluoro-4-hydroxyquinoline-3-carboxylic acid ethyl ester with substituted-benzyl chlorides gave 1-(substituted-benzyl)-6,7-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid ethyl esters. Their treatment with piperazine or N-methylpiperazine in pyridine yielded 1-(substituted-benzyl)-6-fluoro-1,4-dihydro-4-oxo-7-(l-piperazinyl)quinoline-3-carboxylic acid ethyl esters which were hydrolyzed with aqueous sodium hydroxide and then acidified with hydrochloric acid afforded the desired 1-(substituted-benzyl)-6-fluoro-1,4-dihydro-4-oxo-7-(1-iperazinyl)quinoline-3-carboxylic acids. The 6,8-difluoro analogs were prepared similarly using 6,7,8-trifluoro-4-hydroxyquinoline-3-carboxylic acid ethyl ester as a starting material. Some of these quinolones demonstrated fairly good antibacterial activities. Among them, 6-fluoro-1-(4-fluorophenylmethyl)-1,4-dihydro-7-(1-iperazinyl)-4-oxoquinoline-3-carboxylic acid ( 7d ) and 6,8-difluoro-1-(3-fluorophenylmethyl)-1,4-dihydro-7-(1-piperazinyl)-4-oxoquinoline-3-carboxylic acid ( 8c ) are two of the best.     

Synthesis of tricyclic analogues of methyllycaconitine using ring closing metathesis to append a B ring to an AE azabicyclic fragment

The synthesis of several ABE tricyclic analogues of the alkaloid methyllycaconitine 1 is reported. The analogues contain two key pharmacophores: a homocholine motif formed from a tertiary N-ethyl amine in a 3-azabicyclo[3.3.1]nonane ring system and a 2-(3-methyl-2,5-dioxopyrrolidin-1-ly)benzoate ester 4. The synthesis of the ABE tricyclic analogues of MLA 1 began with selective allylation at C-3 of 3 to produce allyl beta-keto ester 4. Double Mannich reaction of 4 with ethylamine and formaldehyde produced bicyclic amine 5 The C-9 ketone of bicyclic amine 5 was selectively reduced to form bicyclic alcohols 6 and 7 which were subsequently allylated to form dienes 8 and 9. Ring closing metathesis of dienes 8 and 9 afforded tricyclic ethers 11 and 12, respectively, the C-8 ester of which was reduced to a hydroxymethyl group to form ABE tricyclic analogues 13 and 14. Addition of allylmagnesium bromide to the C-9 ketone of 20 afforded dienes 21 and 22, which underwent ring closing metathesis to form tricyclic esters 23 and 24, respectively. Reduction of the C-8 ethyl ester of 23 and 24 to a hydroxymethyl group afforded diols 25 and 26 respectively. The 2-(3-methyl-2,5-dioxopyrrolin-1-ly)benzoate ester was introduced by conversion of alcohols 13, 14, 25 and 26, to the anthranilate esters 16, 17, 27 and 28 using N-(trifluoroacetyl)anthranilic acid 15 followed by fusion with methylsuccinic anhydride to afford the substituted anthranilates 18, 19, 29 and 30 containing the key 2-(3-methyl-2,5-dioxopyrrolidin-1-ly)benzoate ester pharmacophore.     

Indolizine derivatives. VII. indolizines via cyclizations of 2-(2-Pyridyl)methylene-1,3-diketones and −1,3-Keto esters

The reaction of 3-(2-pyridyl)methylene-2,4-pentanedione with acetic anhydride gives at 60° 1-(1-acetoxy-3-methyl-2-indolizinyl)ethanone ( 3a ) or, in the presence of 2,4-pentanedione, 3-(2-acetyl-3-methyl-7-indolizinyI)-2,4-pentanedione ( 7a ) in good yield. In refluxing acetic anhydride, 1-(3-methyl-2-indolizinyl)ethanone ( 4a ) is the main product. In refluxing dimethyl sulfoxide the cycloaddition product, 3-[2-acetyl-3-(2-pyridyl)-l-indolizinyl)]-2,4-pentanedione ( 6 ), is obtained. Ethyl 2-(2-pyridyl)methylene-3-oxobutanoate and ethyl 2-(2-pyridyl)methylene-3-oxo-3-phenylpropanoate behave analogously. The stereochemistry of the keto esters has a marked influence on the course of cyclization. The mechanisms are discussed.     

Synthesis and stereoisomerism of derivatives of <Emphasis Type="Italic">tert</Emphasis>-butyl 7-alkylideneceph-3-em-4-carboxylate

By condensation of tert-butyl 3-methyl-7-oxoceph-3-em-4-carboxylate and its 3-acetoxymethyl analog with acetylmethylenetriphenylphosphorane and 3-trimethylsilylpropyn-2-ylindenetriphenylphosphorane tert-butyl 7Z-acetylmethylene-3-methylceph-3-em-4-carboxylate and also 7Z-and 7E-isomers of tert-butyl 3-acetoxymethyl-7-(3-trimethylsilylpropyn-2-ylidene)ceph-3-em-4-carboxylates were synthesized. Oxidation of these compounds with 1 equivalent of meta-chloroperbenzoic acid gave their 1R-and 1S-sulfoxides, and oxidation with 2 equivalents gave the corresponding sulfones. According to data from ¹H NMR spectroscopy, the carbonyl of the β-lactam descreens proton H-9 of the alkylidene group in the 7Z-isomers more strongly than in the 7E-isomers, shifting their signals to weaker field. Analogous shifts of the H-6 signal to weaker field was observed in the 1R-sulfoxides in comparison with that for the 1S-sulfoxide. These results were confirmed by X-ray crystallography of tert-butyl 7Z-acetylmethylene-3-methyl-1S-oxoceph-3-em-4-carboxylate and tert-butyl 7Z-acetylmethylene-3-methyl-1,1-dioxoceph-3-em-4-carboxy-late. In memory of Professor A.A. Potekhin __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, 618–626, April, 2008.     

Diastereoselective synthesis of substituted tetrahydroquinoline-4-carboxylic esters by a tandem reduction-reductive amination reaction

A diastereoselective synthesis of 1-methyl-2-alkyl- and 2-alkyl-1,2,3,4-tetrahydroquinoline-4-carboxylic esters has been developed from methyl (2-nitrophenyl)acetate (1). The method involves alkylation of 1 with an allylic halide, ozonolysis of the double bond, and catalytic hydrogenation. The final hydrogenation initiates a tandem sequence involving (1) reduction of the aromatic nitro group, (2) condensation of the aniline or hydroxylamine(8) nitrogen with the side chain carbonyl, (3) reduction of the resulting nitrogen intermediate, and (4) reductive amination of the tetrahydroquinoline with formaldehyde produced in the ozonolysis to give a methyl (+/-)-1-methyl-2-alkyl-1,2,3,4-tetrahydroquinoline-4-carboxylate. Removal of the formaldehyde prior to hydrogenation gives the simple (+/-)-2-alkyl derivatives. The products are isolated in high yield as single diastereomers having the C-2 alkyl group cis to the C-4 carboxylic ester. The reaction has been extended to the synthesis of tricyclic structures with similar high diastereoselection.     

Diversity-oriented synthesis of functionalized pyrrolo[3,2-d]pyrimidines with variation of the pyrimidine ring nitrogen substituents

Nine 2,4-dioxo-2,3,4,5-tetrahydro-1H-pyrrolo[3,2-d]pyrimidine-6-carboxylic acid benzyl esters 12 were synthesized in four steps from 4-oxo-N-(PhF)proline benzyl ester 7 by a general method in which elements of molecular diversity were readily added onto the pyrimidine nitrogens. Conversion of 4-oxoproline 7 into the corresponding aminopyrrole 8 using benzyl-, allyl-, and isopropylamine followed by treatment with phenyl, allyl, and ethyl isocyanate gave nine different ureas 9. 4-Ureido-1H-pyrrole-2-carboxylic acid benzyl esters 9 were then converted into the respective pyrrolo[3,2-d]pyrimidines 12 using trichloroacetyl chloride in acetonitrile followed by treatment with Cs(2)CO(3). Crystallization from toluene gave the desired deazapurines in 37-55% overall yield from proline 7.     

Esters of Substituted 2,3,7-Triazabicyclo[3.3.0]oct-3-ene-4-carboxylic acids and 1,2,7-Triazaspiro[4.4]non-2-ene-3-carboxylic acids in Alkylation and Acylation

Esters of substituted 2,3,7-triazabicyclo[3.3.0]oct-3-ene-4-carboxylic acids react with acetone in the presence of hydrogen chloride (bromide) affording esters of substituted 2-(1,1-dimethyl-3-oxobutyl)-2,3,7-triazabicyclo[3.3.0]oct-3-ene-4-carboxylic acids. Reactions of esters of substituted 2,3,7-triazabicyclo[3.3.0]octa-1(5),3-diene-4-carboxylic acids with 1-adamantanol in trifluoroacetic acid resulted in esters of substituted 2-(1-adamantyl)- 2,3,7-triazabicyclo[3.3.0]octa-1(5),3-diene-4-carboxylic acids.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 2, 2005, pp. 252–263.Original Russian Text Copyright © 2005 by Stepakov, Molchanov, Kostikov.     

Cyclopropanation of N-substituted 3-aryl-2-cyanoprop-2-enamides and derivatives of 5,5-Dimethyl-2-oxo-2,5-dihydrofuran-3-carboxylic acid and 2-oxochromene-3-carboxylic acid with bromine-containing zinc enolates

Zinc enolates derived from 1-aryl-2,2-dibromoalkanones react with N-substituted 3-aryl-2-cyanoprop-2-enamides and 5,5-dimethyl-2-oxo-2,5-dihydrofuran-3-carboxylic and 2-oxochromene-3-carboxylic acid derivatives to give, respectively, N-substituted 2-alkyl-3-aryl-2-aroyl-1-cyanocyclopropane-1-carboxamides, 6-(4-bromobenzoyl)-4,4,6-trimethyl-2-oxo-3-oxabicyclo[3.1.0]hexane-1-carboxylic acid ethyl ester and morpholide, and 1-alkyl-1-aroyl-2-oxo-1a,7b-dihydrocyclopropla[c]chromene-1a-carboxylic acids as a single geometric isomer. Treatment of 1-alkyl-1-aroyl-2-oxo-1a,7b-dihydrocyclopropa[c]chromene-1a-carboxylic acids with carboxylic acid anhydrides leads to the formation of the corresponding 9c-alkyl-1-aryl-3,4-dioxo-9b,9c-dihydro-2,5-dioxacyclopenta[2,3]cyclopropa[1,2-a]naphthalen-1-yl carboxylates.     

Pd(II)-catalyzed vinylic polymerization of norbornene and copolymerization with norbornene and copolymerization with norbornene carboxylic acid esters

The vinylic polymerization of norbornene and its copolymerization with norbornene carboxylic acid methyl esters were investigated. Norbornene was polymerized by us using di-μ-chloro-bis-(6-methoxybicyclo[2.2.1]hept-2-ene-endo-5σ,2π)-palladium(II) as catalyst. The polymerization time can be decreased by a factor of 100000 by activation of the catalyst with methylaluminoxane (MAO). With this palladium catalyst activated by MAO, 140 t of norbornene can be polymerized per mol palladium per h. This catalyst system was much more active than [Pd(CH₃CN)₄](BF₄)₂ ( I ). The polymerization of norbornene by (6-methoxybicyclo[2.2.1]hept-2-ene-endo-5σ,2π)-palladium(II) tetrafluoroborate was also possible but it was not as fast as the polymerization by Pd catalysts activated with MAO. We were also able to obtain copolymers of norbornene and 5-norbornene-2-carboxylic acid methyl ester (exo/endo = 1/4 or 2/3) containing between 15 and 20 mol-% ester units. The copolymerization of norbornene and 2-methyl-5-norbornene-2-carboxylic acid methyl ester (exo/endo = 7/3) was faster than the copolymerization mentioned before. In contrast the homopolymerization of 2-methyl-5-norbornene-2-carboxylic acid methyl ester was 10 times slower than that of 5-norbornene-2-carboxylic acid methyl ester (exo/endo = 1/4).     

Synthesis and cytotoxic properties of 7α-chloro-3-methyl-1,1-dioxoceph-3-ems, substituted with amide or keto group at position 4

7α-Chloro-3-methyl-1,1-dioxoceph-3-ems with amide or keto group at position 4 have been synthesized by structural modification of 7α-chloro-3-methyl-1,1-dioxoceph-3-em-4-carboxylic acid. Screening of these compounds for cytotoxic activity revealed compounds with specific activity against cancer cells in vitro, capable of effective inhibition of the growth of sarcoma S-180 in vivo. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, 1849–1859, December 2007.     

Synthesis and properties of 3-substituted 2h-1,2,4-benzothiadiazine 1,1-dioxides

The ethyl ester and amides of 2H-1,2,4-benzothiadiazine-3-carboxylic acid 1,1-dioxide were obtained by reaction of 2-aminobenzenesulfonamide with diethyl oxalate or oxamic acid esters in the presence of sodium methoxide. The hydrolysis, animation, and hydrazinolysis of the ester were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 479–483, April, 1976.     

Synthesis of 6′-carbamoylmethylthio-5′-cyano-1′,4′-dihydro-3,4′-bipyridine-3′-carboxylic and 6′-carbamoylmethylthio-5′-cyano-1′,4′-dihydro-4,4′-bipyridine-3′-carboxylic esters and investigation of their stability. 2. Esters of 6′-carbamoylmethyl-thio-5′-cyano-1′,4′-dihydro-4,4′-bipyridine-3-carboxylic acids

The stability of solutions of esters of 6′-carbamoylmethylthio-5′-cyano-2′-methyl-1′,4′-dihydro-4,4′-bipyridine-3′-carboxylic acids was investigated by HPLC. The corresponding esters of 6′-carbamoylmethylthio-5′-cyano-4,4′-bipyridine-3′-carboxylic acids,esters of 8-cyano-5-methyl-3-oxo-7-(4-pyridyl)-2,3-dihydro-7H-thiazolo-[3,2-a]pyridine-6-carboxylic acids, methyl 3-amino-2-carbamoyl-6-methyl-4-(4-pyridyl)-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylate, and methyl 3-amino-2-carbamoyl-6-methyl-4-(4-pyridyl)-thieno[2,3-b]pyridine-5-carboxylate were synthesized as standard compounds (typical impurities). Analysis by HPLC was realized under the conditions of reverse-phase chromatography. It was established that solutions of the investigated compounds (with mixtures of acetonitrile with phosphate buffer, having pH values of not less than 3 and not more than 5, as solvents) are stable for one month when the solutions are stored in a place protected against light. It is also necessary to use chromatographic systems in which the aqueous components have pH 3–5 during determination of the purity of the esters of 6′-carbamoylmethylthio-5′-cyano-2′-methyl-1′,4′-dihydro-4, 4′-bipyridine-3′-carboxylic acid by HPLC in order to separate the analyzed sorbates and their typical impurities more completely. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 841–848, June, 2007.     

Reaction of methyl 1-bromocyclopentane-1-carboxylate with zinc and 3-aryl-2-cyanoprop-2-enamides

Reformatsky reaction of methyl 1-bromocyclopentane-1-carboxylic acid with 3-aryl-2-cyanoprop-2-enamides and their N-methyl derivatives afforded 10-aryl-6,8-dioxo-7-azaspiro[4.5]decane-9-carbonitriles and 10-aryl-7-methyl-6,8-dioxo-7-azaspiro[4.5]decane-9-carbonitriles, respectively.