Extracellular oxidation of D-glucose by some members of the Enterobacteriaceae

Extracellular D-glucose oxidation by 5 enterobacterial species was studied with the purpose of selecting conditions useful for taxonomic studies. Extracellular production of gluconate from ¹⁴C-glucose by bacterial cells was evidenced by DEAE-cellulose paper chromatography. Escherichia coli oxidized glucose only when pyrroloquinoline quinone (PQQ) was added, whereas Serratia marcescens, Yersinia frederiksenii, Erwinia cypripedii and Cedecea lapagei oxidized D-glucose without added PQQ. 2-Deoxyglucose was found to be an excellent non-metabolized analogue of D-glucose in oxidation experiments. D-glucose oxidation was inhibited by KCN, p-chloromercuribenzoic acid and carbonyl cyanide m-chlorophenylhydrazone; and activated by p-benzoquinone. Iodoacetate had no action. Comparative cellulose thin-layer chromatography including 2-ketogluconate and 2,5-diketogluconate (produced by Janthinobacterium lividum) as standards, showed that gluconate was oxidized to 2-ketogluconate by S. marcescens and E. cypripedii, and 2-ketogluconate was oxidized to 2,5-diketogluconate by E. cypripedii. The diversity of D-glucose oxidation products in the Enterobacteriaceae could have some taxonomic applications.     

The Betti base: absolute configuration and routes to a family of related chiral nonracemic bases

A detailed protocol for the resolution of the Betti base [i.e. 1-(α-aminobenzyl)-2-naphthol] was investigated and the absolute configuration of the two isomers was established by means of an X-ray diffractometric study. A series of optically active derivatives was also prepared. The list includes the N-benzyl- and the N,N,O-trimethyl derivatives. The N,N-dimethyl derivative was prepared in racemic form by means of the Betti reaction and was resolved into the two enantiomers with an extremely easy and efficient procedure. The O-methyl derivative was prepared in a racemic form and subjected to resolution. The configuration of each base was determined by correlation with the configuration of the Betti amine.     

Enzymatic resolution of sec-butylamine

Resolution of (±)-sec-butylamine by Candida antarctica lipase provided a very low enantiomeric excess of the residual amine when either ethyl or vinyl butyrate was used as the acylating agent. The enantiomeric excess was increased by using ethyl esters of long chain fatty acids. The rate of the reaction was increased by using methyl t-butyl ether as a solvent. (S)-sec-Butylamine of very high enantiomeric excess was obtained by C. antarctica lipase catalyzed acylation with ethyl decanoate in methyl t-butyl ether.     

Ion-pair extraction behavior of divalent metal cations using neutral di-Schiff base ligands derived from 1,2-cyclohexanediamine and o-phenylenediamine

Di-Schiff base ligand, N,N'-bis(2-pyridylmethylidene)-trans-1,2-diiminocyclohexane (trans-BPIC), having sufficient hydrophobicity acts as neutral bidentate ligand in ion-pair extraction of divalent metal cations into nitrobenzene with picrate anion. In present study, the effect of steric restriction by chemical structure around imine-N donor atoms in trans-BPIC analogs on their complexation with divalent metal cations in ion-pair extraction was investigated by using N,N'-bis(2-pyridylmethylidene)-cis-1,2-diiminocyclohexane (cis-BPIC) and N,N'-bis(2-pyridylmethylidene)-o-diiminobenezene (BPIB). The former was used to observe the effect by geometrical restriction and the latter was by conjugate restriction. In BPIB-NaPic system, the higher extractability was obtained than those in cis- and trans-BPIC systems, and this result seems to be led by the increase of steric distortion originated from conformational restriction. Namely, it is considered that the extractability can be controlled by steric restriction on the complexation.     

The reaction of n-butyllithium and potassium t-amyloxide with butenes

1-Butene, cis/trans-2-butene and 2-methylpropene were polymetalated by treatment with the product obtained by combination of n-butyllithium and potassium t-amyloxide. Polymetalation was determined by quenching with deuterium oxide and analysis by gas chromatograph-mass spectrometer combination. The rate of metalation was followed by n-butane evolution. Approximately 20% of cis-2-butene exclusively was realized after H₂O quench of the reaction of 1-butene/n-butyllithium/ potassium t-amyloxide for 1.0 h at room temperature. A small amount (7%) of a cis/trans-2-butene mixture was isomerized to 1-butene and the remaining 2-butene was enriched in the cis-isomer. The assumption that n-butylpotassium was the active metalating species was confirmed by the dependency on lithium/potassium ratio, relative ease of organometallic decomposition at 70°, rapid reaction with monochlorostyrene at room temperature, and the similarity to organosodium and organopotassium isomerization of olefins.     

Stereoselective synthesis of 1,2-cis galactosides: synthesis of a glycolipid containing Galα1-6Gal component from Zygomycetes species

An α-selective galactosylation was demonstrated under various conditions. Among these α-galactoside approaches, high α-selectivity was achieved by the virtue of 4,6-O-di-tert-butylsilylene (DTBS) group. Yield was further improved by the influence of a 2-O-benzylated donor compared to 2-O-benzoylated donor. This method was then applied to the first highly stereoselective synthesis of a newly found trisaccharide glycosphingolipid in Zygomycetes species.     

Palladium-catalyzed synthesis of indane and cyclobuta[a]indenes from homoallylic alcohols derived from Baylis-Hillman adducts: base-dependent stereoselectivity for the benzylidene group in cyclobuta[a]indene

Various indane and cyclobuta[a]indene derivatives were synthesized by palladium-catalyzed cyclization of homoallylic alcohol derivatives prepared from Baylis-Hillman adducts. Especially, cyclobuta[a]indene derivative was synthesized stereoselectively by palladium-catalyzed 5-exo-trig/4-exo-trig cascade cyclization, albeit in moderate yield. The Z isomer was formed exclusively in the presence of Et₃N by usual Heck-type carbopalladation process while E isomer with Cs₂CO₃ most likely by a concerted metalation/deprotonation (CMD) process.     

Thermodynamic, IR spectral and X-ray diffraction studies of the ����-cyclodextrin-para-aminobenzoic acid�� inclusion complex

The inclusion complex with stoichiometric composition 1:1 was formed as a result of intermolecular interactions between para-aminobenzoic acid and ??-cyclodextrin. The stability constant of ????-cyclodextrin-para-aminobenzoic acid?? inclusion complex at 289, 292 and 313 K was calculated by the Ketelar equation. The influence of temperature on the stability of ????-cyclodextrin-para-aminobenzoic acid?? inclusion complex was also examined, and thermodynamic parameters involved in the complex formation (??G, ??H, ??S) were calculated. Supramolecular complex formation between para-aminobenzoic acid and ??-cyclodextrin was confirmed by X-ray diffraction and IR spectroscopy studies.     

Preparation of N-alkyl-N′-carboalkoxy guanidines: unexpected effective trans-alkoxylation transforming the 2,2,2-trichloroethoxycarbonyl into various carbamates

A range of N-alkyl-N′-Boc guanidines was simply synthezized from monoprotected Boc-1H-pyrazole-1-carboxamidine by reaction with primary amines. Synthesis of the hindered (R)-N-methylbenzyl-N′-Troc guanidine was achieved from the corresponding thiourea by the action of ammonia. Transformation of the Troc group into others carbamate groups, including Boc, was simply obtained by refluxing in the appropriate alcohol.     

Enantioselective total synthesis of (2R,3R,6R)-N-methyl-6-(deca-1′,3′,5′-trienyl)-3-methoxy-2-methylpiperidine, an insecticidal alkaloid

An insecticidal piperidine alkaloid, (2R,3R,6R)-N-methyl-6-(deca-1′,3′,5′-trienyl)-3-methoxy-2-methylpiperidine, was efficiently synthesized in a stereoselective manner starting from d-alanine. Chiral center at C-6 was controlled by hydrogenation of imine and side chain was introduced by Julia olefination. The absolute configuration of natural product was determined to be 2R, 3R, 6R.     

A concise stereoselective synthesis of pterosin B

Pterosin B is a naturally occurring indanone found in bracken fern (Pteridium aquilinum) that displays a variety of interesting pharmacological properties, but for which few stereoselective syntheses exist. Herein we describe a 7-step stereoselective synthesis of (2R)-pterosin B via 6-bromo-5,7-dimethylindan-1-one whose structure was confirmed by NOE analysis and structure determination by X-ray crystallography. The hydroxyethyl chain was introduced via a Suzuki-Miyaura cross-coupling reaction. The 2-methyl group was introduced stereoselectively by methylation of a SAMP [(S)-1-amino-2-methoxymethyl)pyrrolidine] hydrazone and the chiral auxiliary was removed to produce (2R)-pterosin B. The structure of pterosin B was confirmed by specific rotation and structural determination by X-ray crystallography.     

Characterization of a Family B DNA Polymerase from the Hyperthermophilic Crenarchaeon Ignicoccus hospitalis KIN4/I and Its Application to PCR

A family B DNA polymerase gene from the hyperthermophilic crenarchaeon Ignicoccus hospitalis KIN4/I was highly expressed under the control of T7lac promoter of pET-28ARG in Escherichia coli BL21-CodonPlus(DE3)-RIL cells. The produced I. hospitalis (Iho) DNA polymerase was purified by heat treatment followed by HisTrap? HP column and HiTrap? SP column chromatographies. The molecular mass of the purified Iho DNA polymerase was 88 kDa as estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The optimal pH for Iho DNA polymerase activity was 7.0 and the optimal temperature was 70 °C. Iho DNA polymerase was strongly activated by the presence of magnesium ion at an optimum concentration of 3 mM. The optimal concentration of KCl for Iho DNA polymerase activity was 60 mM. The half-life of the enzyme at 94 °C was about 2 h. The optimal conditions for polymerase chain reaction (PCR) were determined. Iho DNA polymerase possesses 3′?→?5′ exonuclease activity, and the fidelity of the Iho DNA polymerase was similar to that of Pfu and Vent DNA polymerases. However, Iho DNA polymerase provided more enhanced efficiency of PCR amplification than Pfu and Vent DNA polymerases. Iho DNA polymerase could successfully amplify a 2-kb λ DNA target with a 10-s extension time and could amplify a DNA fragment up to 8 kb λ DNA.     

A pH- and temperature-sensitive macrocyclic graft copolymer composed of PEO ring and multi-poly(2-(dimethylamino) ethyl methacrylate) lateral chains

A novel method for the synthesis of macrocyclic graft copolymers was developed through combination of anionic ring-opening polymerization (AROP) and atom transfer radical polymerization (ATRP). A linear α,ω-dihydroxyl poly(ethylene oxide) with pendant acetal protected hydroxyl groups (l-poly(EO-co-EEGE)) was prepared first by the anionic copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE). Then l-poly(EO-co-EEGE) was cyclized. The crude cyclized product containing the linear byproduct was hydrolyzed and purified by being treated with α-CD. The pure cyclic copolymer [c-poly(EO-co-Gly)] was esterified by reaction with 2-bromoisobutyryl bromide, and then used as ATRP macroinitiators to initiate polymerization of 2-(dimethylamino) ethyl methacrylate (DMAEMA), and a series of pH- and temperature-sensitive macrocyclic graft copolymers composed of a hydrophilic PEO as the ring and PDMAEMA as side chains (c-PEO-g-PDMAEMA) were obtained. The behavior of pH- and temperature-sensitive macrocyclic copolymers was studied in aqueous solution by fluorescence and dynamic light scattering (DLS). The critical micellization pH values of macrocyclic graft copolymers and their corresponding linear graft copolymers (l-PEO-g-PDMAEMA) were measured. Under the same conditions, the cyclic graft copolymer with the shorter side chains gave the higher critical micellization pH value. The c-PEO-g-PDMAEMA showed the lower critical micellization pH value than the corresponding l-PEO-g-PDMAEMA. The average hydrodynamic diameters (D _h) of the micelles were measured by DLS with the variation of the aqueous solution pH value and temperature.     

Synthesis of cis-3,4-diaryl α-methylene-γ-butyrolactams via sonochemical Barbier-type reaction

A series of cis-3,4-diaryl α-methylene-γ-butyrolactams were synthesized by the addition reaction of 3-phenylallyl bromide with N-tosyl aldimine via sonochemical Barbier-type reaction condition and then followed by the in situ intramolecular amidation. The cis-3,4-diaryl α-methylene-γ-butyrolactam was obtained as the sole regio- and stereoisomeric product when N-tosyl aldimine was used as the substrate whereas the monoaryl α-methylene-γ-butyrolactam was also generated when N-phenyl aldimine was used.     

Sustained release applications of a fluoroalkyl ester-functionalized amphiphilic cyclodextrin by inclusion complex formation with water-soluble drugs in supercritical carbon dioxide

An amphiphilic γ-cyclodextrin, selectively functionalized with perfluorobutanoyl group, octakis(6-O-perfluorobutanoyl)-γ-cyclodextrin (γ-CyD-F), was investigated as a potential sustained release carrier for hydrophilic drugs, taking molsidomine (MOL) as a model drug. Supercritical carbon dioxide, an environmentally benign solvent, was used for the preparation of MOL/γ-CyD-F inclusion complexes. The molecular encapsulation of MOL by the amphiphilic cyclodextrin was confirmed by differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD) studies. Additionally, ¹H NMR spectroscopy was used to investigate the inclusion mode of drug with the γ-CyD-F. The in-vitro release of MOL from the peanut oil suspensions into aqueous phase was found to be significantly retarded by the complexation with γ-CyD-F, mainly due to the hydrophobic properties associated with the γ-CyD-F.     

Synthesis and properties of BCOD-fused trithiasapphyrin and trithiabenzosapphyrins

Bicyclo[2.2.2]octadiene(BCOD)-fused trithiasapphyrin was prepared by 3+2 condensation of BCOD-fused thiatripyrrane with BCOD-fused bithiophene. The BCOD-fused trithiasapphyrin was successfully converted to pentabenzo[b,g,l,q,v]sapphyrin by the thermal retro-Diels-Alder reaction. In this case, trithiapentabenzo[b,g,l,q,v]- and trithiadibenzo[g,q]sapphyrins were selectively prepared by control of the temperature in the thermal retro-Diels-Alder reaction.     

Radiolytically prepared poly(vinyl alcohol) hydrogel containing α-cyclodextrin

α-Cyclodextrin (α-CD) was immobilized by the radiation-induced gelation of poly(vinyl alcohol) (PVA). An aqueous solution of 4-nitrophenol (4-Np) was added upon the PVA hydrogel containing α-CD in a quartz cell. Absorption spectra of the hydrogel phase have demonstrated that 4-Np permeates into the hydrogel and is included by α-CD. When pure toluene was added upon the hydrogel, the rate of the permeation of toluene was affected by the inclusion complexation with α-CD.     

Photoconversion of o-hydroxycinnamates to coumarins and its application to fluorescence imaging

(E)-o-Hydroxycinnamates were synthesized and their photochemical behavior was investigated in liquid and solid states. It was confirmed by ¹H NMR spectroscopy that the (E)-o-hydroxycinnamates converted into the corresponding coumarins via (Z)-o-hydroxycinnamate intermediates. The photoconversion was greatly accelerated in the presence of p-toluenesulfonic acid. The optical properties of the cinnamates were compared with those of the corresponding coumarins. Fluorescence imaging was successfully accomplished by photoirradiation of PMMA films containing the cinnamates.