Chemo-enzymatic synthesis of comb polymers

The paper describes the synthesis and characterization of comb polymers by a two-step chemo-enzymatic process. In the first step macromonomers bearing unsaturation at the chain end were prepared by lipase catalyzed ring-opening polymerization (ROP) of ε-caprolactone (CL) and 1,5-dioxepane-2-one (DXO). The ROP was carried out in bulk at 60 °C under anhydrous conditions using 2-hydroxyethyl methacrylate (HEMA) as the initiator. The DP of the macromonomers was controlled by regulating the monomer: HEMA molar feed concentration. The macromonomers were then homo- or co-polymerized in the second step with alkyl methacrylate monomers (methyl methacrylate or HEMA) using AIBN initiated free radical polymerization. Characterization of the polymers was done by ¹H NMR, SEC and DSC techniques.     

Synthesis of 2-(4-amino substituted benzylidene) indanone analogues from aromatic nucleophilic substitution (SNAr) reaction

A novel, efficient and convenient procedure has been developed for the synthesis of 2-(4-amino-substituted benzylidene)indanone derivatives. In the first step, the reaction of 4-fluorobenzaldehyde with 5, 6-dimethoxy-2, 3-dihydro-1H-inden-1-one in the presence of NaOH in EtOH was described. In the next step, a variety of aliphatic and aromatic amines were reacted with 2-(4-fluorobenzylidene)-5, 6-dimethoxy-2, 3-dihydro-1H-Inden-1-one via aromatic substitution (S_NAr) reaction to produce 2-(4-aminobenzylidene)-5, 6-dimethoxy-2, 3-dihydro-1H-Inden-1-one derivatives as a novel class of 1-indanones. These products have been successfully prepared in good to excellent yields. ^1?H and ^13?C NMR, FT-IR spectroscopy and CHN analysis supported the proposed structures of the products.     

The octant rule. XIV. synthesis and circular dichroism of α-exo and endo-deuteriobicyclo[3.2.1]octan-3-one and 6,6-dimethybicyclo[3.1.1]heptan-3-one

(1R,5S)-2S-Deuteriobicyclo[3.2.1]octan-3-one ($\text{1}$) and (1R,5S)-2R-Deuteriobicyclo[3.2.1]octan-3-one ($\text{2}$), prepared by diazomethane ring enlargement of (1S,4R)-2(exo)-deuteriobicyclo-[2.2.1] heptan-2-one and (1S,4R)-2(endo)-deuteriobicyclo[2.2.1]heptan-2-one respectively, both gave (?) n-π^* circular dichroism (CD) Cotton effects, Δε^max₂₉₄ = ?0.05 and Δε^max₂₉₄=?0.1, respectively, in hydrocarbon solvent. (1S,5R)-2S-Deuterio-6,6-diaethylbicyclo[3.1.1] heptan-3-one ($\text{3}$) and (1S,5R)-2R-deuterio-6,6-dimethylbicyclo[3.1.1] heptan-3-one ($\text{4}$), prepared from (-) myrtenal, both exhibited extraordinary vibrational fine structure for the n-π^* CD transitions observed in hydrocarbon solvent and oppositely?signed CEs, Δε^max₂₈₂=?0.01 and Δε^max₂₇₉=+0.01 respectively in CF₃CH₂OH solvent.     

Synthetic, spectral, and antimicrobial aspects of biologically relevant coordination compounds of dioxomolybdenum(VI) and oxovanadium(V)

Heterocyclic ketimines, 5-nitro-3-(indolin-2-one)hydrazinecarbothioamide (L¹H), 5-nitro-3-(indolin-2-one)hydrazinecarboxamide (L²H), 6-nitro-3-(indolin-2-one)hydrazinecarbo-thioamide (L³H), and 6-nitro-3-(indolin-2-one) hydrazinecarboxamide (L⁴H), were prepared by the condensation of thiosemicarbazide and semicarbazide hydrochloride (in the presence of sodium acetate) in ethanol with the respective ketones. The dioxomolybdenum(VI) complexes and oxovanadium(V) complexes have been prepared by mixing dioxobis(2,4-pentanedinato)molybdenum(VI) in 1: 2 molar ratios and vanadium oxytrichloride in 1: 1 and 1: 2 molar ratios with monobasic bidentate ketimines. The resulting complexes have been characterized by elemental analysis, conductance measurements, and spectral studies, including IR, ¹H NMR, and UV spectra. The ketimines and their corresponding metal complexes have been tested on a number of pathogenic bacteria and fungi in order to assess their growth inhibition potency at different concentrations. The article was submitted by the authors in English.     

Synthesis and application of polytetrahydrofuran-grafted polystyrene (PS-PTHF) resin supports for organic synthesis

Cross-linked polystyrene (PS) with polytetrahydrofuran (PTHF) chains were prepared for use in solid phase organic synthesis (SPOS). The resins were prepared from styrene, styrene-PTHF macromonomers and cross-linkers 1,4-bis[4-vinylphenoxy]butane or divinylbenzene by suspension polymerization. The styrene-PTHF macromonomers were prepared by cationic polymerization of 4-vinylbenzyl bromide and 4-(4-vinylphenoxy)butyl iodide activated by silver hexafluoroantimonate and 4-(5-hydroxypentyl)styrene activated by triflic anhydride. Alternatively, polytetrahydrofuran-grafted polystyrene (PS-PTHF) resins could also be directly prepared from 5-hydroxypentyl JandaJel by cationic polymerization using triflic anhydride as the initiator. These PS-PTHF resins exhibited good swelling characteristics across a wide spectrum of polar and non-polar solvents. These resins were used in the synthesis of 3-methyl-1-phenyl-2-pyrazolin-5-one, which requires β-ketoester formation at low temperature (−78 °C), resulting in good yield and product purity; whereas the same synthesis carried out on PEG-grafted PS (PS-PEG) resin resulted in incomplete synthesis.     

Synthesis of pyrimido[4,5-e][1,4]oxazepin-5-ones

Eighteen novel pyrimido[4,5-e][1,4]oxazepin-5-ones were prepared directly via the reaction of either ethyl 4-chloro-2-phenyl-5-pyrimidinecarboxylate (Ia) or ethyl 4-chloro-2-m-chlorophenyl-5-pyrimidinecarboxylate (Ib) with a variety of substituted 2-(alkylamino)ethanols. A typical example was the preparation of 8,9-dihydro-9-methyl-2-phenylpyrimido[4,5-e][1,4]-oxazepin-5(7H)-one (IIa) from the reaction of Ia with 2-(methylamino)ethanol. Hydrolytic cleavage of the lactone ring in IIa with sodium hydroxide solution, followed by acidification with hydrochloric acid afforded 4-[(2-hydroxyethyl)methylamino]-2-phenyl-5-pyrimidinecarboxylic acid (IV). Reactions of IIa with concentrated ammonium hydroxide or hydrazine also caused cleavage of the lactone ring, giving the corresponding amide (V) or hydrazide (VI), respectively. Structural assignments were supported by infrared and nuclear magnetic resonance spectra.     

3-亚甲基六氢苯并呋喃-2(3H)-酮的简便合成

以氧化环己烯为原料,在正丁基锂作用下与乙腈经开环反应制得2-羟基环己基乙腈(2);2依次经水解、内酯化、二甲胺甲基化、甲基化和Hofmann降解反应合成了α-亚甲基-γ-丁内酯类化合物--3-亚甲基六氢苯并呋喃-2(3H)-酮,总收率30.4%,其结构经¹H NMR,¹³C NMR和HR-MS(EI)确证。     

SYNTHESIS AND POLYMERIZATION OF α-METHACRYLYOXYLETHYLOXYCARBONYLMETHYL-ω-(N,N-DIETHYLDITHIOCARBAMYL)POLYSTYRENE MACROMONOMERS

Polystyrene macromonomers with different molecular weight were prepared by radical polymerization of styrene(St) in benzene using β-methacryloxylethyl 2-N,N-diethyldithiocarbamylacetate (MAEDCA) as a monomer-iniferter.Characterization of the macromonomer by ~1H-NMR showed that the end groups were α-methacrylyoxylethyloxycarbonyl-methyl and ω-(N,N-diethyldithiocarbamyl). The macromonomer was difficult to homopolymerize, but it was easilycopolymerized with methyl methacrylate (MMA) initiated by AIBN to form graft copolymers (PMMA-g-PSt) with PStbranches randomly distributed along the PMMA backbone. Copolymerization reaction and the structure of the graftcopolymers were strongly affected by M_n and concentration of the macromonomer. The composition and M_n of the purified graft copolymer were determined by ~1H-NMR and GPC analysis.     

A study of the oxyanion effect in reactions of 2-methyl-2-propen-1-ol

Optimum conditions for the self reaction of the potassium alkoxide of 2-methyl-2-propen-1-ol to give 3,5,5,-trimethyltetrahydropyran-2-ol (7) have been developed. Evidence is presented to demonstrate that the key carbon carbon bond forming step in this reaction formally involves an unusual type of Ene reaction between 2-methylpropenal and the allylic alkoxide anion in which stepwise or highly asynchronous hydride transfer precedes carbon carbon bond formation. Under different reactions conditions the condensation of 2-methylpropenal with the potassium alkoxide of 2-methyl-2-propen-1-ol proceeds to give the bicyclic lactone, 6-endo-hydroxy-7-exo-(2-methyl allyioxymethyl)-3-oxa-1,5,7-trimethyl bicyclo[3,3,1]nonan-2-one (11), the crystal structure of which is reported.     

Fabrication of biodegradable poly(trimethylene carbonate) networks for potential tissue engineering scaffold applications

Biodegradable poly(trimethylene carbonate) (PTMC) networks were prepared by photopolymerization of linear (L)‐ and star (S)‐shaped PTMC macromonomers for potential tissue engineering scaffold applications. The L‐ (M_n, 6400) and S‐shaped (M_n, 5880) PTMC macromonomers were synthesized using 1,4‐butane diol and 2‐ethyl‐ 2‐hydroxyl‐propane‐1,3‐diol co‐initiated ring‐opening polymerization of trimethylene carbonate (TMC) in the presence of stannous octoate and subsequent acrylation with acryloyl chloride. Chemical structures of the PTMC macromonomers and their corresponding networks were characterized by ¹H NMR and ¹³C NMR spectroscopy. The human endothelial cell line, EA.hy926 was used to test the biocompatibility, cell adhesion, and proliferation behavior of both PTMC networks. The PTMC networks made from the S‐shaped macromonomers exhibited superior cell adhesion and proliferation behavior than those made of the linear macromonomers. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis of well‐defined macromonomers by the combination of atom transfer radical polymerization and a click reaction

This article presents a new strategy for synthesizing a series of well‐defined macromonomers. Bromine‐terminated polystyrene and poly(t‐butyl acrylate) with predetermined molecular weights and narrow distributions were prepared through the atom transfer radical polymerization of styrene and t‐butyl acrylate initiated with ethyl 2‐bromoisobutyrate. Then, azido‐terminated polymers were obtained through the bromine substitution reaction with sodium azide. Catalyzed by CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine, the azido end group reacted with propargyl methacrylate via a 1,3‐dipolar cycloaddition reaction, and ω‐methacryloyl‐functionalized macromonomers were thus obtained. The end‐group transformation yields were rather high, as characterized by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectra and ¹H NMR analysis. By this effective and facile approach, some novel macromonomers that otherwise are difficult to achieve, such as poly(ethylene oxide)‐block‐polystyrene, were easily prepared. Radical homopolymerizations of these macromonomers were performed, and a series of comb polymers were prepared. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6103–6113, 2006     

Zur Photochemie von (Z,Z)-2,7-Cyclodecadien-1-on und 4,8-Cyclododecadien-1-on. Synthese und Eigenschaften von Tricyclo[5.3.0.02,8]decan-Systemen

On the Photochemistry of (Z,Z)-2,7-Cyclodecadien-1-one and 4,8-Cyclododecadien-1-one. Synthesis and Properties of Tricyclo[5.3.0.0^2,8]decane Systems Irradiation of (Z,Z)-2,7-cyclodecadien-1-one ( 3 ) yields (Z,Z)-3,7-cyclodecadien-1-one ( 12 ) or tricyclo-[5.3.0.0^2,8]decan-4-one ( 16 ), depending on the reaction conditions. Irradiation of 4,8-cyclododecadien-1-one ( 28 ) results also in a light-induced transannular [2 + 2] cycloaddition, yielding tetracyclo[7.3.0.0^2,100^3,6]dodecan-1-one ( 30 ). Starting from 16 , the preparation of tricyclo[5.3.0.0^2,8]dec-4-ene ( 19 ), tricyclo[5.3.0.0^2,8]dec-4-ene ( 21 ) and tricyclo[5.3.0.0^2,8]deca-3,5-diene ( 24 ) is described. The ¹H-NMR and ¹³C? NMR spectra of the newly prepared compounds are discussed. In the case of 19, 21 , and 24 , the electronic structure is discussed on hand of their PE spectra.     

A synthesis of (±)-Δ2-α-Lycoren-7-one,the key intermediate for the total synthesis of (±)-lycorine

(±)-α-Lycoran-3,5-dione (14a) was prepared from octahydrophenanthridin-3-one (8b) obtained by two methods starting from 5-aryl-4-nitrocyclohexene (2) and 1-hydroxyl-2-aryl-5-oxo-cyclohexanecarboxylic acid (10), both of which were prepared by the Diels-Alder reaction of 3,4-methylenedioxy - ω - nitrostyrene with butadiene and the Robinson annelation of 3,4-methyl- enedioxy - phenylpyruvic acid (9) with methyl vinyl ketone, respectively, 14a was converted into (±)Δ²-α-lycoren-7-one (22b), which has been transformed into (±)-lycorine (1) by Torssell     

Constrained Dipeptide Surrogates: 5- and 7-Hydroxy Indolizidin-2-one Amino Acid Synthesis from Iodolactonization of Dehydro-2,8-diamino Azelates

The constrained dipeptide surrogates 5- and 7-hydroxy indolizidin-2-one N-(Boc)amino acids have been synthesized from L-serine as a chiral educt. A linear precursor ∆⁴-unsaturated (2S,8S)-2,8-bis[N-(Boc)amino]azelic acid was prepared in five steps from L-serine. Although epoxidation and dihydroxylation pathways gave mixtures of hydroxy indolizidin-2-one diastereomers, iodolactonization of the ∆⁴-azelate stereoselectively delivered a lactone iodide from which separable (5S)- and (7S)-hydroxy indolizidin-2-one N-(Boc)amino esters were synthesized by sequences featuring intramolecular iodide displacement and lactam formation. X-ray analysis of the (7S)-hydroxy indolizidin-2-one N-(Boc)amino ester indicated that the backbone dihedral angles embedded in the bicyclic ring system resembled those of the central residues of an ideal type II’ β-turn indicating the potential for peptide mimicry.     

Total synthesis of (+)-kalafungin using a tandem Michael-Dieckmann approach

A stereoselective synthesis of the antibiotic kalafungin 1 is reported. A key step involved the tandem Michael-Dieckmann reaction between methyl 2-methoxy-6-methylbenzoate 11 and the α,β-unsaturated lactone (R)-6-(2-(tert-butyldimethylsilyloxy)ethyl)-4-methoxy-5,6-dihydropyran-2-one 10, which was prepared from (S)-aspartic acid. The C5 alkyl substituent was introduced by the use of methylmagnesium bromide and subsequent stereoselective reduction. A sequence of oxidations followed by acid-catalyzed epimerization delivered (+)-kalafungin 1.     

Hydrolyse acide des diazocétones secondaires: Participation des nucléophiles

In the acid hydrolysis of two secondary diazoketones showing rate-determining protonation, 3-diazo-butan-2-one ( 1 ) and 1-phenyl-1-diazo-acetone ( 4 ), the nature of the (rapid) decomposition step of the intermediate diazonium ion was studied by product analysis. In the presence of strong nucleophiles, the reaction with Cl^?, Br^?, I^? and SCN^? follows the Swain-Scott relationship. SCN^? formed thiocyanates; isothiocyanates could not be detected. Both results indicate nucleophilic participation in the substitution step. For the accompanying elimination reaction (the amount of which is independent of added base) the isotope effect k_H/k_D = 2,4 in the hydrolysis of 1–d₃ is in favour of an E2 type mechanism. – Addition of HSCN to methyl-vinylketone at 0° yields nearly exclusively 4-thiocyanato-butan-2-one, which at 25° in the presence of HSCN is slowly rearranged to 4-isothiocyanato-butan-2-one.     

Preparation,Surface, and Biological Activities of Some Novel Metallosurfactants

A series of novel metallosurfactants (III_a-d) was prepared and evaluated as surface active agents. The synthesis was carried out through two steps: the first was the reaction of fatty acids (I_a-d) (lauric, palmitic, myristic and steric acid) with morpholine (tetrahydro-1,4-oxazine) to give morpholin-4-yl-alkan-1-one (II_a-d), respectively. The second step is reaction of product of the first step (compounds II_a-d) with Fe (III) to give (III_a-d) metallosurfactants. The chemical structures of the prepared compounds were elucidated with elemental analysis, FTIR and ¹H NMR spectroscopic tools. The surface properties of the prepared metallosurfactants were determined at different temperature 25, 35, and 45°C. The surface tension (γ), critical micelle concentration (CMC), surface tension at CMC (γ_cmc), effectiveness (π_cmc), efficiency (Pc_2o), maximum surface excess (Γ_max), and minimum surface area (A_min) were determined. Thermodynamic data including, free energy, entropy and enthalpy changes (ΔG, ΔS, ΔH) for adsorption at the air–water interface and also for micellization in the bulk of surfactant solutions were calculated. The antimicrobial activity of the prepared compounds was determined via the inhibition zone diameter technique against Gram-positive, Gram-negative bacteria, and some fungal strains as mold and yeast. The results indicate that the prepared ferrosurfactants have a good surface properties and biological activities against the tested microorganism.     

Novel benzopyranopyridine derivatives of 2-amino-3-formylchromone

Enol lactones such as 4-hydroxy-6-methyl-2H-pyran-2-one (triacetic acid lactone, TAL) and 4-hydroxycoumarin when treated with 2-amino-3-formylchromone under basic conditions afforded 3-acetoacetyl benzopyranopyridones and benzopyranopyridines, respectively. A series of pyrazole derivatives was prepared by the reaction of 3-acetoacetyl benzopyranopyridones with different hydrazines. All compounds were characterised on the basis of spectral data and their antibacterial activity evaluated.     

Novel Synthesis of 3,5,5-Trimethyl-4-(2-butenylidene)-cyclohex-2-en-1-one,a Major Constituent of Burley Tobacco Flavour

The acetylenic diol 2 , prepared by reaction of but-3-yn-2-ol dianion with 2,6,6-trimethyl-4,4-ethylenedioxy-cyclohex-2-en-1-one ( 1 ), afforded 3,5,5-trimethyl-4-(2-butenylidene)-cyclohex-2-en-1-one ( 4 ), a major constituent of Burley tobacco flavour, upon LiAlH₄ reduction and hydrolysis. Vomifoliol ( 5 ) and blumenol C ( 6 ) were major by-products in this reaction.     

Ring-opening oligomerization reactions using aluminium complexes of schiff's bases as initiators

Bifunctional telechelics with defined structure can be prepared by oligomerization of oxiranes, β-butyrolactone and L-lactide using aluminium Schiff's base complexes as initiators. Chiral initiator (SALCENAlCl) shows a stereoelective character leading to preferential oligomerization of one enantiomer from a racemic monomer mixture. The reaction with β-butyrolactone proceeds through O-alkyl cleavage. Alkoxy Schiff's bases aluminium complexes are used for oligomerization of L-lactide. All the prepared oligomers were fully characterized by IR, elemental analysis, ¹H and ¹³C NMR and GPC.