Diastereoselective reduction of β-keto carbonyl compounds by cultured plant cells

The diastereoselective reduction of β-keto carbonyl compounds such as 2-benzamidomethyl-3-oxobutanoates and 2-methyl-2-(2-propenyl)cyclopentan-1,3-dione by cultured cells of higher plants was investigated. The reduction of the 2-benzamidomethyl-3-oxobutanoates by Parthenocissus tricuspidata diastereoselectively produced the (2R,3S)-2-benzamidomethyl-3-hydroxybutanoates, whereas the reduction by Gossypium hirsutum gave the (2S,3S)-2-benzamidomethyl-3-hydroxybutanoates. The (2R,3S)/(2S,3S) predominance in the reduction with Nicotiana tabacum, Glycine max, and Catharanthus roseus was reversed by the change in the structure of the alkoxyl group in the substrate. On the other hand, the reduction of 2-methyl-2-(2-propenyl)cyclopentan-1,3-dione by P. tricuspidata produced (2R,3S)-3-hydroxy-2-methyl-2-(2-propenyl)cyclopentan-1-one, whereas the reaction by N. tabacum, G. max, C. roseus, and G. hirsutum gave (2S,3S)-3-hydroxy-2-methyl-2-(2-propenyl)cyclopentan-1-one.     

Beam-foil lifetime study of then=3 complex in al-like Ti9+

The beam-foil spectrum obtained using a beam of Ti³⁺ ions of energy 10 MeV has been studied over the wavelength range from 14 nm to 80 nm. New assignments are suggested for 18 levels belonging to the levels of the 3p ³, 3s 3p 3d and 3s ² 4p configurations. The lifetimes of these levels, as determined from conventional multi-exponential curve fitting of their intensity decay curves, are typically about 30% longer than is forecast by theory. The same decay curves have also been used to represent the effect of cascade repopulation on the decay curves obtained for the resonance doublet levels of the 3s 3p ² and 3s ² 3d configurations. A discussion is given of the possible techniques for cascade correction in beam-foil lifetime measurements, and of the inclusion of a window function to represent the vignetting effect close to the foil. Lifetimes obtained using these techniques for the 3s ² 3d levels (38±6 ps for J=3/2, 36±5 ps for J=5/2), and the 3s3p ^{2 2} S level (99±6 ps),² P levels (60±15 ps for J=1/2, 50±15 ps for J=3/2) and² D levels (820±30 ps for j=3/2, 870±40 ps for J=5/2) are in good agreement with theoretical predictions.     

Amination of 5-Spiro-Substituted 3-Hydroxy-1,5-dihydro-2H-pyrrol-2-ones

The 3-hydroxy-1,5-dihydro-2H-pyrrol-2-one motif is a valuable scaffold in drug discovery. The replacement of the 3-oxy fragment in 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones-based compounds with a 3-amino one (3-amino analogs of 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones, 3-amino-1,5-dihydro-2H-pyrrol-2-ones) can play a crucial role in their biological effect. Thus, approaches to 3-amino-1,5-dihydro-2H-pyrrol-2-ones are of significant interest. We developed an approach to 5-spiro-substituted 3-amino-1,5-dihydro-2H-pyrrol-2-ones that could not be obtained using previously reported approaches (reactions of 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones with amines). The developed approach is based on the thermal decomposition of 1,3-disubstituted urea derivatives of 5-spiro-substituted 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones, which were prepared via their reaction with carbodiimides.     

Synthesis of 2′-deoxy-5-fluoro-5′-O-1″,3″,2″-oxazaphosphacyclohexa-2″-yluridine 2″-oxide and related compounds

2′,3′-O-Isopropylidene-5′-O-1″,3″,2″-oxazaphosphacyclohex-2″-yl-uridine 2″-oxide has been obtained by the action of phosphoryl chloride and N-methylmorpholine, followed by 3-aminopropan-1-ol, on 2',3'-O-isopropy-lidineuridine. A similar reaction carried out on 3'-O-acetylthymidine, followed by removal of the acetyl group gave 5′-O-1″,3″,2″-oxazaphospha-2″-yl-thymidine 2″-oxide. Both of these compounds were obtained more conveniently by treatment of 2',3'-O-isopropylideneuridine and thymidine respectively with 2-chloro-1,3,2-oxazaphosphacyclo-hexane 2-oxide in pyridine. Similar treatment of 2′-deoxy-5-fluorouridine gave 2′-deoxy-5-fluoro-5′-O-1″,3″,2″-oxazaphosphacyclohex-2″-yluridine 2″-oxide. The latter compound was tested for activity against S 180 Crocker sarcoma and L 1210 mouse leukaemia. Only a marginal activity against the S 180 sarcoma was detected. However inactivity of the compound in inducing leukopenia indicated that it might be of low toxicity and that further testing of the compound would be justified.     

Nucleophilic cyclization of 3-alkynylquinoxaline-2-carbonitriles into pyrido[3,4-b]quinoxalines

3-Alkynylquinoxaline-2-carbonitriles have been synthesized from 3-chloroquinoxaline-2-carbonitrile via the Sonogashira reaction. Treatment of 3-alkynylquinoxaline-2-carbonitriles with an alkylamine or ammonia has been shown to produce stable enamines, e.g., (Z)-3-(2-aryl-2-aminovinyl)quinoxaline-2-carbonitriles. Their base-induced cyclization gave the previously unknown pyrido[3,4-b]quinoxalin-1(2H)-imines or pyrido[3,4-b]quinoxalin-1-amines. 3-Alkynylquinoxaline-2-carbonitriles were directly transformed into pyrido[3,4-b]quinoxalin-1(2H)-imines by heating with an alkylamine and K₂CO₃ in DMF. The ionization constants, and absorption and fluorescent properties of the resulted pyrido[3,4-b]quinoxalin-1(2H)-imines were measured.     

Raman optical activity of tartaric acid and related molecules

The Raman optical activity spectra of (2R, 3R) (+)- and (2S,3S) (?)-tartaric acid, (2R, 3R) (+)-dimethyl tartrate, (2R,3R) (?)-2,3-butanediol and (2S, 3S) (+)-dibenzoyl tartaric acid are presented. A large couplet at about 500cm^?1 in the first three molecules, which probably originates in deformations of a chiral structural unit, might serve as an indicator of conformation and absolute configuration.     

Reaction of the zinc enolate derived from 1,1-dibromo-3,3-dimethylbutan-2-one with 3-aryl-2-cyanopropenoic acid amides and esters and 2-oxochromene-3-carboxamides

Zinc enolate derived from 1,1-dibromo-3,3-dimethylbutan-2-one reacts with 3-aryl-2-cyanoprop-2-enamides and aryl 3-aryl-2-cyanoprop-2-enoates to give the corresponding derivatives of 3-aryl-2-(2,2-dimethylpropanoyl)-1-cyanocyclopropane-1-carboxylic acid as a single stereoisomer with cis arrangement of the hydrogen atoms at the cyclopropane ring. The reactions of the same zinc enolate with 3-morpholinocarbonyl-2H-chromen-2-one and 2-morpholinocarbonyl-3H-benzo[f]chromen-3-one lead to formation of 1-(2,2-dimethylpropanoyl)-1a-morpholinocarbonyl-1a,7b-dihydrocyclopropa[c]chromen-2-one and 1-(2,2-dimethylpropanoyl)-1a-morpholinocarbonyl-1a,9c-dihydrobenzo[f]cyclopropa[c]chromen-2-one, respectively as a single stereoisomer.     

Identification of new lines in the beam-foil spectrum of B II–IV

Ten, six, and twenty-one new lines appearing in the beam-foil spectra of boron (30–200 nm) have been identified in B II, B III, and B IV, respectively. Energies have been determined with higher accuracy than obtained before for the 2p3s ¹ P ⁰, 2s6d ³ D, 2p3p ³ D, 2p3p ³ S, 2p3p ³ P, and 2p3p ¹ D terms in B II. First energy values are also reported for the 2s6d ¹ D and 2s7d ³ D terms in B II.     

Synthesis of methyl (E)-2-[(3S,4S)-4-hydroxy-3-(pent-3-yloxy)-pyrrolidin-2-ylidene]propanoate and its unusual recyclization

Methyl (2E,4S,5S)-5-hydroxy-6-mesyloxy-2-methyl-4-(pent-3-yloxy)hex-2-enoate was synthesized from l-tartaric acid. Attempted substitution of the mesyloxy group by the reaction with NaN₃ directly led to methyl (E)-2-[(3S,4S)-4-hydroxy-3-(pent-3-yloxy)pyrrolidin-2-ylidene]propanoate. The latter on treatment with CF₃COOH and then NaOH gave methyl (2E)-2-methyl-4-[(S)-oxiran-2-yl]-4-(pent-3-yloxy)but-2-enoate.     

Synthesis of 5H-pyridazino[4,5-b]indoles and their benzofurane analogues utilizing an intramolecular Heck-type reaction

The title ring systems were prepared from pyridazin-3(2H)-one precursors in novel, efficient pathways. 2-Methylbenzo[b]furo[2,3-d]pyridazin-1(2H)-one was synthesized via a regioselective nucleophilic substitution reaction of a 2-methyl-4,5-dihalopyridazin-3(2H)-one with phenol followed by an intramolecular Heck-type reaction. The same molecule and its 6-phenyl analogue were also prepared via reaction of 2-methyl-5-iodopyridazin-3(2H)-one or 2-methyl-5-chloro-6-phenylpyridazin-3(2H)-one, respectively, with 2-bromophenol or 2-iodophenol followed by Pd-catalyzed cyclodehydrohalogenation. Moreover, a new approach for the synthesis of 2-methyl-2,5-dihydro-1H-pyridazino[4,5-b]indol-1-ones was also elaborated utilizing a Heck-type ring closure reaction on 5-[(2-bromophenyl)amino]-2-methylpyridazin-3(2H)-ones which were obtained via Buchwald-Hartwig amination of 2-methyl-5-halopyridazin-3(2H)-ones with 2-bromoaniline.     

Preparation of methano[1,3]oxazolo[3,2-a]quinolin-2-ones from 2-(pent-3-en-2-yl)anilines

Acid-catalyzed Claisen aromatic rearrangement of ethyl N-(pent-3-en-2-yl)-N-phenylglycinate leads to the formation of ethyl N-[2-(pent-3-en-2-yl)phenyl]glycinate. The reaction of sodium salt of N-acetyl-2-(pent-3-en-2-yl)-4-methylaniline with methyl bromoacetate afforded ethyl N-acetyl-N-[4-methyl-2-(pent-3-en-2-yl)phenyl]glycinate. The hydrolysis of synthesized esters, the conversion of the obtained acids by treating with ethyl chloroformate into munchnones, and the subsequent [3+2]-cycloaddition provided methoxazoloquinoline structures.     

Oxidative cyclization of 3-oxopropanenitriles with α,β-unsaturated amides by manganese(III) acetate. Regio- and stereoselective synthesis of 4-cyano-2,3-dihydrofuran-3-carboxamides

4-Cyano-2,3-dihydrofuran-3-carboxamides were obtained from the oxidative cyclization of 3-oxopropanenitriles with unsaturated amides using manganese(III) acetate. Treatment of 3-oxopropanenitriles with (2E)-3-(5-methyl-2-furyl)acrylamide and (2E)-3-(2-thienyl)acrylamide gave 2-(5-methyl-2-furyl) and 2-(2-thienyl) substituted 4-cyano-2,3-dihydrofuran-3-carboxamides in moderate yields, respectively. However, (2E)-3-(2-furyl)acrylamide and (2E)-3-phenylacrylamide did not produce any product under the same conditions. On the other hand, reaction of a dienamide such as (2E,4E)-5-phenylpenta-2,4-dienamide with 3-oxopropanenitriles gave diastereomeric mixtures of 2-(2-vinylphenyl)-4-cyano-2,3-dihydrofuran-3-carboxamides. Mechanisms are proposed for the formation of all of these compounds.     

Enantiodivergence in the reduction of α-methyl and α-halomethyl enones by microorganisms

Enones (Z)-3-methyl-(Z)-3-chloromethyl- and (Z)-3-bromomethyl-4-R-3-buten-2-one (R = n-pentyl, phenyl, 2′- and 4′-chlorophenyl, 3′- and 4′-nitrophenyl, 4′-methoxyphenyl) were synthesized and subjected to reduction by the microorganisms Saccharomyces cerevisiae andGeotrichum candidum. Whereas the bioreduction of 3-methy-4-R-3-buten-2-ones afforded the corresponding (S)-4-R-3-methybutan-2-ones, the bioreduction of 3-chloromethyl- and 3-bromomethyl-4-R-3-buten-2-ones afforded the corresponding (R)-4-R-3-methybutan-2-ones.     

Asymmetric synthesis of all isomers of α-methyl-β-phenylserine

This report describes the synthesis of enantiomerically pure (2R,3R)-, (2R,3S)-, (2S,3S)- and (2S,3R)-2-amino-3-hydroxy-2-methyl-3-phenylpropanoic acids, four quaternary α-amino acids, using a stereodivergent synthetic route and starting from (S)- and (R)-N-Boc-N,O-isopropylidene-α-methylserinals. The key step involves the asymmetric Grignard additions to the above chiral aldehydes, in which high levels of asymmetric induction are observed.     

2-(2-Furyl)-1(3)H-imidazo[4,5-f]quinoline. Synthesis and electrophilic substitution reactions

2-(2-Furyl)-1(3)H-imidazo[4,5-f]quinoline was synthesized by the Weidenhagen reaction of quinoline-5,6-diamine with furfural. Its alkylation with methyl iodide in the system KOH-DMSO gave two isomeric N-methyl derivatives, 2-(2-furyl)-1-methyl-1H- and 2-(2-furyl)-3-methyl-3H-imidazo[4,5-f]quinolines, the latter prevailing. 2-(2-Furyl)-3-methyl-3H-imidazo[4,5-f]quinoline was brought into electrophilic substitution reactions: bromination, nitration, formylation, acylation, sulfonation. Depending on the reaction conditions, electrophilic attack could be directed at both furan ring and quinoline fragment.     

Synthesis,structure elucidation and plants growth promoting effects of novel quinolinyl chalcones

The readily synthesized 3-(4-Hydroxy-1-methyl-1,2-dihydro-2-oxoquinolin-3-yl)-1-phenyl-1H-pyrazole-4-carbaldehyd (5) and 3-(2-Oxo-2H-chromen-3-yl)-1-phenyl-1H-pyrazole-4-carbaldehyde (6) were utilized as a convenient starting precursor materials for synthesis of novel enone system 4-hydroxy-1-methyl-3-(4-(2H-2-oxo-chromen-3-yl)prop-2-enoyl)-1-phenyl-1H-pyrazol-4-yl)quinolin-2(1H)-one (7) and4-hydroxy-1-methyl-3-(2E)-3-(3-(2-oxo-2H-chromen-3-yl)-1-phenyl-1H-pyrazol-4-yl)acryloyl)quinolin-2(1H)-one (8). Simple homonuclear NOE experiment (NOESY 1D) method was performed for structure elucidation of the novel quinolinyl chalcones. The synthesized compounds have been estimated for their effect of growth on some selective crop of plants (Hibiscus, Mint and Basil).     

Ring size and substituent steric effects in cyclic ketene-N,O/S-acetal trifluoroacetylations

Trifluoroacetylations of cyclic ketene-N,O/S-acetals exhibit a ring size effect. The five-membered rings 2,4,4-trimethyl-2-oxazoline, 2-methyl-2-oxazoline, and 2-methyl-2-thiazoline, each form cyclic ketene-N,O/S-acetal intermediates which then react with trifluoroacetic anhydride to give β-monotrifluoroacetylation products. Conversely, the six-membered ring 2-methyl-2-oxazine gives its β,β-bistrifluoroacetylation product. In situ-generated five-membered ring N-Me cyclic ketene-N,O-acetals, 3,4,4-trimethyl-2-methylene-oxazolidine, and 3-methyl-2-methylene-oxazolidine, and six-membered ring 3-methyl-2-methylene-1,3-oxazinane were each β,β-bistrifluoroacetylated. However, 3-methyl-2-methylene-oxazolidine also afforded a γ-lactam by an iodide-catalyzed rearrangement of its β,β-bistrifluoroacetylated derivative. In situ-generated 3-methyl-2-methylene-thiazolidine gives both β-mono- and β,β-bistrifluoroacetylation products and no lactam, in contrast to its N,O-analog 3-methyl-2-methyleneoxazolidine.     

Stereoselective synthesis of 2-O-MEM-2,3-unsaturated-β-O-glycosides and elaboration to useful synthetic tools

The glycosylation of alcohols by the new 2-O-MEM-substituted d-galactal-derived allyl epoxide affords the corresponding alkyl 2-O-MEM-3-deoxy-β-d-threo-hex-2-enopyranosides through a completely 1,4-regio- and a highly to completely substrate-dependent stereoselective glycosylation processes. The glycosides obtained can be regioselectively transformed into corresponding 3-deoxy-β-O-glycosides, 3-deoxy-β-d-threo-hexopyranosid-2-uloses, and 3,4-dideoxy-β-d-glycero-hex-3-enopyranosid-2-uloses, which are useful synthetic tools for further transformations.     

Collision cross sections for excitation energy transfer in Na* (3P 1/2)+K(4S 1/2)⇔Na*(3P 3/2)+K(4S 1/2) processes

The cross sections for the excitation energy transfer between the 3² P _J states of sodium atoms by collisions with ground-state potassium atoms have been measured by resonant Doppler-free two-photon spectroscopy, where the population densities of directly pumped and collisionally excited Na(3P _J )(J=1/2, 3/2) levels were probed by counter-propagating Na(3P _J ) → Na(4D _{3/2, 5/2}) excitation and detected with the thermionic diode. Cross sections of σ(3P _1/2 → 3P _3/2)=190 Ų±20% and σ(3P _3/2 → 3P _1/2)=100 Ų±20% were found. The theoretical calculations taking into account the long-range interaction termsR ^?6,R ^?8 andR ^?10 yield a value σ(3P _1/2 → 3P _3/2)=165 Ų. On the basis of these long-range interaction potentials the differential cross section has been calculated and compared with recently published experimental data. Very good agreement between the theoretical and experimental data was found.     

Synthesis and investigation of anti-inflammatory and anticonvulsant activities of novel coumarin-diacylated hydrazide derivatives

A number of novel coumarin derivatives synthesized by the reaction of 3-carbonyl chloride coumarin with some substituted aryl acid hydrazides to investigate their anti-inflammatory and anticonvulsant activities. Carrageenan (0.1 ml of 1%, w/v) was injected subplantarly in the right paw of rats to induce an acute model of inflammation. Anti-inflammatory efficacy was evaluated for 5 hours at 3 different dosages 5, 10, 25 mg/kg. After that, the changes in the level of paw edema volumes and percentage inhibition of all groups were observed and the most effective coumarin derivative was found as N'-(2-hyroxybenzoyl)-2-oxo-2H-chromene-3-carbohydrazide. In addition, N’-(2-oxo-2H-chromene-3-carbonyl)nicotinohydrazide, (E)-N’-(3-(4-hydroxyphenyl)acryloyl)-2-oxo-2H-chromene-3-carbohydrazide, and N’-(5-amino-2-hydroxybenzoyl)-2-oxo-2H-chromone-3-carbohydrazide showed their anti-inflammatory effects in a dose-dependent manner. On the other hand, pentylenetetrazole (PTZ, 80 mg/kg, i.p.)-induced seizure model was used to investigate the anticonvulsant activities of six newly synthesized coumarin derivatives in mice. Hybrid compound of salicylic acid hydrazide and 3-carbonyl chloride coumarin (8d) was found the most promising anticonvulsant agent among all treatment groups according to the onset of seizure and survival rate. Moreover, (E)-N'-cinnamoyl-2-oxo-2H-chromene-3-carbohyrazide (8b) and (E)-N'-(3-(4-hyroxyphenyl)acryloyl)-2-oxo-2H-chromene-3-carbohydrazide (8c) has potential anticonvulsant efficiency in low doses (30 mg/kg). The anticonvulsant effect of these coumarin derivatives may be through enhanced GABA-mediated inhibition in the brain.