Allyl Ester Groups Research Articles

Understanding the thermodynamic phase equilibria for the allyl acetate, allyl acrylate and allyl methacrylate under CO2 as supercritical solvent

Acrylic acid allyl ester groups show the non-ideal phase equilibria and have slightly or strong polarity. Phase equilibria for the allyl acetate, allyl acrylate and allyl methacrylate in conformity with chain-length play a crucial role as organic monomers in a number of chemical industries. The curves of the solution mixture for allyl acetate, allyl methacrylate, and allyl acrylate under high-pressure supercritical CO2 (super CO2) are examined with the help of a fabricated method at various temperatures within the boundary of (313.2 −393.2) K and pressures within (1.75–16.27) MPa. The three system for super CO2 + allyl acetate, super CO2 + allyl methacrylate and super CO2 + allyl acrylate solutions have critical mixed curves which show largest in p-T space between Tc (- critical temperatures) of super CO2 and allyl acetate or allyl acrylate or allyl methacrylate. The liquid + vapor data of super CO2 of three systems at a fixed pressure decreases with rise in temperature. The super CO2 + allyl acetate, super CO2 + allyl acrylate and super CO2 + allyl methacrylate systems display phase behavior of type-I. For the application at Peng-Robinson equation in theoretical investigation, solubility curves between the predicted and test results of the super CO2 + allyl acetate, super CO2 + allyl acrylate and super CO2 + allyl methacrylate binary systems were obtained the satisfactory agreement. The properties (pc, Tc and ω) and vapor pressure of allyl acetate, allyl acrylate and allyl methacrylate were estimated with group contribution and useful method.

A TCF-Based Carbon Monoxide NIR-Probe without the Interference of BSA and Its Application in Living Cells.

As toxic gaseous pollution, carbon monoxide (CO) plays an essential role in many pathological and physiological processes, well-known as the third gasotransmitter. Owning to the reducibility of CO, the Pd0-mediated Tsuji-Trost reaction has drawn much attention in CO detection in vitro and in vivo, using allyl ester and allyl ether caged fluorophores as probes and PdCl2 as co-probes. Because of its higher decaging reactivity than allyl ether in the Pd0-mediated Tsuji-Trost reaction, the allyl ester group is more popular in CO probe design. However, during the application of allyl ester caged probes, it was found that bovine serum albumin (BSA) in the fetal bovine serum (FBS), an irreplaceable nutrient in cell culture media, could hydrolyze the allyl ester bond, and thus give erroneous imaging results. In this work, dicyanomethylenedihydrofuran (TCF) and dicyanoisophorone (DCI) were selected as electron acceptors for constructing near-infrared-emission fluorophores with electron donor phenolic OH. An allyl ester and allyl ether group were installed onto TCF-OH and DCI-OH, constructing four potential CO fluorescent probes, TCF-ester, TCF-ether, DCI-ester, and DCI-ether. Our data revealed that ester bonds of TCF-ester and DCI-ester could completely hydrolyze in 20 min, but ether bonds in TCF-ether and DCI-ether tolerate the hydrolysis of BSA and no released fluorescence was observed even up to 2 h. Moreover, passing through the screen, it was concluded that TCF-ether is superior to DCI-ether due to its higher reactivity in a Pd0-mediated Tsuji-Trost reaction. Also, the large stokes shift of TCF-OH, absorption and emission at 408 nm and 618 nm respectively, make TCF-ether desirable for fluorescent imaging because of differentiating signals from the excitation light source. Lastly, TCF-ether has been successfully applied to the detection of CO in H9C2 cells.

A turn-on fluorescent probe for palladium(II) detection with a large Stokes shift and lysosomes-targeting ability

Although a number of palladium(II) probes have been developed, most of them have small Stokes shifts and lack good subcellular targeting ability. In this paper, a reaction-based probe (DCF-MPYM-Pd) has been designed and synthesized for palladium(II) detection. The probe was constructed by a fluorescein derivative as the fluorophore and an allyl ester group as the recognition group. The probe exhibited fast response time (5 min), high sensitivity and specificity. Importantly, it has a large Stokes shift and lysosomal targeting capability. In addition, it was demonstrated that the probe can be used to sense palladium(II) in living cells and can accumulate specifically in lysosomes.

An Efficient Method for Constructing Cyclic β-Amino Acids Bearing Quaternary Stereocenters

This paper describes an efficient method for constructing cyclic β-amino acids bearing quaternary stereocenters. NaHMDS-promoted asymmetric α-alkylation was employed to obtain the key intermediates with quaternary stereogenic centers, which were subsequently reduced by NaBH4 in 10% methanol in THF, with high yields and high diastereoselectivities. By removing the allyl ester group and the chiral auxiliary, the corresponding cyclic β-amino acid hydrochlorides were finally obtained.

Hybrasurfs-A New Class of Hyperbranched Surfactants.

A hyperbranched (HB) polyester carrying peripheral allyl groups was prepared by melt-condensation of a suitably designed AB2 monomer bearing two allyl ester groups and one hydroxyl group. The periphery of the hyperbranched polymer was co-clicked with two different organic thiols, namely, hexadecane thiol and 3-mercaptopropionic acid, using the thiol-ene reaction. Three different samples with varying mole fractions of the hydrophilic carboxylic acid groups were prepared; the conformational adaptability of the hyperbranched polymer backbone permitted these amphiphilic systems to form Janus structures that exhibit surfactant-like properties and, therefore, we have termed them hybrasurfs. These polymers behave like clusters of surfactants that have been stitched at the waist by the HB polymer backbone; the Langmuir isotherms revealed the formation of a monolayer, and in two of the samples having higher mole fractions of hexadecyl segments a weak inflection in the isotherm is seen. This suggests a densification, typically implying the crystallization of the alkyl segment at the air-water interface. The monolayers were transferred onto a substrate, and their heights were estimated using atomic force microscopy; the values thus obtained were in reasonable agreement with the expected value. The water contact angles of the substrates bearing the transferred monolayers of the three different samples (transferred at two different points along the isotherm) were measured; it was seen that the sample carrying the highest mole fraction of hexadecyl chains exhibited a significantly larger contact angle when compared to that of the other two samples. Interestingly, these hybrasurfs also formed vesicles in water and were shown to encapsulate water-soluble dyes, such as Eosin Y. Thus, this class of readily accessible amphiphilic HB polymers that behave as a cluster of surfactants opens some interesting possibilities for further exploration.

Poly(γ‐glutamic acid) esters with reactive functional groups suitable for orthogonal conjugation strategies

AbstractWe report on a series of novel poly(γ‐glutamic acid) (PGGA) esters, in which the chemical structure and composition, and the molecular weight are systematically changed. Modification of PGGA of microbial origin, used either as the sodium salt or in the free acid form, by means of alkylation with highly reactive bromides under SN2 conditions, affords copolymers with an essentially random microstructure. These reaction conditions are applied iteratively to achieve full esterification, obtaining allyl or propargyl ester functionalities within the polymer backbone, diluted with inert functional groups, such as benzyl, ethyl, or hexyl ester functionalities. The copolymers have been characterized regarding their chemical structure and thermal and bulk properties using nuclear magnetic resonance, thermogravimetry, differential scanning calorimetry, and X‐ray diffraction techniques. We demonstrate that allyl and propargyl ester groups can be efficiently transformed using click chemistries, such as thiol‐ene or copper(I)‐catalyzed azide–alkyne cycloaddition reactions; such efficient conjugation strategies will be required to transform the native bacterial biopolymer into a material with tailored properties for bulk scale or biomedical applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Characterization of Thermal Degradation of Polytrimethylene Terephthalate by MALDI-TOF Mass Spectrometry

(matrix assisted laser desorption/ionization) mass spectrometry. The structures of the degradation products were determined and the relative compositions were estimated. The MALDI-TOF mass spectra of the thermally degraded PTT sample showed three main series of oligomer products with different end groups, which were carboxyl/carboxyl, carboxyl/allyl, and allyl/allyl. In contrast to the thermal degradation of polyethylene terephthalate (PET), the oligomers containing terephthalic anhydrides were not detected, whereas the formation of oligomers containing the unsaturated allyl ester group was confirmed by mass assignment. From these results, it was concluded that the thermal degradation of PTT proceeds exclusively through the βCH hydrogen transfer mechanism, which is in accordance with the proposed reaction mechanism for the thermal degradation of polybutylene terephthalate (PBT).

Racemic (RSC,SRS)-(2-{[1-allyloxycarbonyl-3-(methylsulfanyl)propyl]iminomethyl}phenyl-κ3S,N,C1)chloridoplatinum(II)

The title compound, [Pt(C15H18NO2S)Cl], was obtained by the cyclo­metallation reaction of cis-bis­(benzonitrile)dichlorido­platinum(II) with N-benzyl­idene-l-methio­nine allyl ester in refluxing toluene. The PtII atom has a square-planar geometry and is tetra-coordinated by the Cl atom and the C, N and S atoms from the benzyl­idene methio­nine ester ligand. In the crystal structure, the S atoms show opposite chiral configurations with respect to the α-carbon of the methio­nine, reducing steric repulsion between the methyl and allyl ester groups.

Facile and Chemoselective Cleavage of Allyl Carboxylic Ester Utilizing NaBH4 in DMSO

A new method for deprotection of allyl carboxylic ester has been observed by using the inexpensive reagent sodium borohydride in dimethyl sulfoxide (DMSO). Aliphatic and aromatic allyl carboxylic ester undergo deprotection smoothly. The allyl ester group can selectively deprotect better than phenol.

Novel aliphatic poly(ester‐carbonate) with pendant allyl ester groups and its folic acid functionalization

AbstractA series of novel poly(ester‐carbonate)s bearing pendant allyl ester groups P(LA‐co‐MAC)s were prepared by ring‐opening copolymerization of L‐lactide (LA) and 5‐methyl‐5‐allyloxycarbonyl‐1,3‐dioxan‐2‐one (MAC) with diethyl zinc (ZnEt2) as initiator. NMR analysis investigated the microstructure of the copolymer. DSC results indicated that the copolymers displayed a single glass‐transition temperature (Tg), which was indicative of a random copolymer, and the Tg decreased with increasing carbonate content in the copolymer. Then NHS‐activated folic acid (FA) first reacted with 2‐aminoethanethiol to yield FA‐SH; grafting FA‐SH to P(LA‐co‐MAC) in the presence of TEA produced P(LA‐co‐MAC)/FA. The structure of P(LA‐co‐MAC)/FA and its precursor were confirmed by 1H NMR and XPS analysis. Cell experiments showed that FA‐grafted P(LA‐co‐MAC) had improved adhesion and proliferation behavior of vero cells on the polymer films. Therefore, the novel FA‐grafted block copolymer is expected to find application in drug delivery or tissue engineering. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1852–1861, 2008

ATRP of Allyl Methacrylate with Alkyl Methacrylates – Crosslinking of Poly(methacrylate)s with Allyl Ester Side Groups

AbstractSummary: Random copolymers of methyl methacrylate (MMA), butyl methacrylate (BMA) and allyl methacrylate (AMA) were prepared via atom transfer radical polymerization (ATRP). AMA is a bifunctional monomer with two double bonds of different reactivity: a highly reactive methacrylate double bond and an allyl ester double bond of lower reactivity. In order to obtain linear polymers with pendant allyl ester groups, the copolymerization conditions have to be optimized with respect to the concentration of AMA, the catalyst system applied – especially the ligand – and the temperature. By means of kinetic studies the reaction parameters for a controlled polymerization were determined. The results obtained show that the higher the temperature and the amount of AMA is the higher is the probability of irregular chain growth and side reactions induced by the pendant allyl ester groups such as hydrogen abstraction from the allyl position or radical addition to the allyl ester double bond. The random copolymers were photochemically crosslinked by using 2,2‐dimethoxy‐2‐phenylacetophenone as photoinitiator. The thermal properties of linear and crosslinked polymers were determined. The glass transition temperatures of both show no significant difference at low AMA content and thus low crosslinking densities.GPC eluograms of MMA/BMA (70:30) copolymers with 5 mol‐% AMA at different conversions.magnified imageGPC eluograms of MMA/BMA (70:30) copolymers with 5 mol‐% AMA at different conversions.

The synthesis of the cyclic antibacterial peptide Kawaguchipeptin B on 11 different DVB cross-linked PS resins

We report the first synthesis of the antibacterial peptide Kawaguchipeptin B. This was carried out on 11 different polystyrene resins ranging from 0.3 to 6.0% DVB cross-linking. The synthesis was accomplished using an Fmoc/ t Bu/Aloc strategy, with side chain resin attachment and a C-terminal allyl ester group for cyclisation. The syntheses of the linear and cyclic forms of the peptide were monitored and surprisingly showed that synthetic efficiency increased with increasing resin-cross linking.

Preparation of Free and of Specifically Protected Oligo[β-Malic Acids] for Enzymatic Degradation Studies

The polyanionic poly[β-(S)-malic acids] (β-PMA) occur in slime molds (myxomycetes), black yeasts and other fungi and are involved in DNA replication. In order to be able to study the cleavage mechanism of β-PMA hydrolases, we have synthesized cyclic and linear oligomers of malic acid (β-OMA) consisting of up to eight residues. To this end, fragments with three different protecting groups were prepared, with allyl ester groups on the C-terminus, TBDPS groups at the O-terminus, and benzyl ester groups at the side chains (Schemes 2, 3, 7). Selective deprotection and fragment coupling (COCl2/C5H5N/CH2Cl2/-75 °C) gave dimers, tetramers, and octamers, either fully protected or specifically protected at the O- or C-terminus or at the side chain acid groups, and also fully deprotected oligoacids (Schemes 3-7). The new compounds were fully characterized (Rf, IR, 1H- and 13C-NMR spectroscopy, mass spectrometry and elemental analysis or high-resolution electrospray mass spectrometry). Enzymatic degradation experiments with the previously prepared cyclo-tetramer, the unprotected, and the O- or C-terminally protected samples of linear β-OMAs show that the enzyme from Physarum polycephalum is an exo-hydrolase cleaving the chain from the O-terminus.

Chemoenzymatic Synthesis of Biotinylated Ras Peptides and Their Use in Membrane Binding Studies of Lipidated Model Proteins by Surface Plasmon Resonance

Characteristic peptides, which have the same lipid modifications as their parent proteins and labels, by which they can be traced, for example, the biotin group, are efficient reagents for the study of signal transduction processes using lipid-modified Ras pro- teins. Such peptide conjugates often contain both acid- and base-labile groups, and their synthesis calls for the application of protecting groups that can be removed selectively and under ex- tremely mild conditions. These criteria are met by the enzyme-labile choline (Cho) ester group. Choline esters can be cleaved at pH 6.5 and room temperature by employing the enzyme butyrylcho- line esterase from horse serum. By using this enzymatic protecting group techni- que as the key step, access to the characteristic S-palmitoylated and S-far- nesylated C terminus of the human N- Ras protein was successfully achieved. The conditions under which these enzy- matic deprotections proceed are so mild that no undesired side reaction is ob- served (that is no hydrolysis or b elim- ination of the thioester and no acid- mediated attack on the double bonds of the farnesyl group). In addition to this technique, the allyl ester group was removed by means of Pd 0 -mediated allyl transfer to accepting nucleophiles. This reaction was exploited to construct bio- tin-labeled lipidated peptides, which correspond to the C terminus of N-Ras, and labeled analogues thereof. The lipi- dated and biotinylated peptides served as anchors for a protein moiety in an artifical membrane in a BIAcore surface plasmon resonance system. The stability of the membrane insertion was moni- tored by surface plasmon resonance after the binding of streptavidin to the biotin heads of farnesylated or farnesy- lated and palmitoylated peptides. Thus, it was shown that a double hydrophobic modification of the peptides is necessary to obtain stable insertion of the conju- gates.

クロロトリメチルシランを介在させたアリル化ゼラチンの合成

In order to develop biocompatible materials, many workers have studied on conjugation of gelatin with synthetic polymers, for example, by graft polymerization of vinyl monomers onto gelatin in aqueous solution or by dry-blending of gelatin powder with synthetic polymers.So, it was tried to esterify carboxyl groups of the aspartic and glu tamic acid residues of gelatin with a functional alcohol, and a reactive gelatin modified with allyl ester groups was newly obtained by chlorotrimethylsilane mediated reaction of gelatin and allyl alcohol. The degree of esterification was found to be determined by the 1HNMR spectroscopy.The resulting allylated gelatin wa s proven to cause graft polymerization through its allyl groups with styrene monomer by the action of radical initiator in an organic solvent to result in a gelatin/synthetic polymer conjugate.

Aryllead triacetates as synthons for the synthesis of biflavonoids. Part 1. Synthesis and reactivity of a flavanonyllead triacetate

The 8-triacetoxyplumbylflavane derivative 11 was prepared in 4 steps in 28% overall yield from 4′,5,7-flavanone. It reacted with the benzofuranone ally β-keto ester 12 to yield a 8-(benzofuran-2yl)flavanone 13 in 66%. Removal of the allyl ester group and cleavage of the dioxolane ring afforded the 8-(3-oxobenzofuran-2-yl)flavanone. This reaction shows that complex polyfunctional aryllead triacetates can be made and selectively coupled with activated ketones.

A regiocontrolled and stereocontrolled synthesis of allylsilanes from β-silyl enolates

The α-lithiated diphenylphosphine oxides 3 react with methyl iodide to give the phosphine oxides 4 and 5 in a ratio of 3–4 : 1. The corresponding reaction with aldehydes gives all four diastereoisomeric alcohols 7–10, which are not suitable for the synthesis of allylsilanes by a Wittig–Horner reaction. The β-dimethyl(phenyl)silyl enolates 13–15 and 25–28 react with aldehydes to give aldol products with high diastereoselectivity. The benzyl and allyl ester groups can be cleaved from these aldols to give the acids 16–18 and 29–32. The acids, in turn, can be induced to undergo decarboxylative elimination stereospecifically either in a syn or an anti sense to give the allylsilanes 19, 20, 23, 24, 33, 34 and 39–41. A similar series of reactions can be carried out with the β-trimethylsilyl enolates 45 and 46 giving the allylsilanes 49, 50, 53 and 54.