Allyl Methyl Ether Research Articles

ChemInform Abstract: Pd(II)‐Catalyzed Dehydrogenative Olefination of Terminal Arylalkynes with Allylic Ethers: General and Selective Access to Linear (Z)‐1,3‐Enynes.

AbstractAllyl phenyl ethers give better yields than allyl methyl ethers and allyl methyl thioethers.

Thiol–Ene Click Chemistry: Computational and Kinetic Analysis of the Influence of Alkene Functionality

The influence of alkene functionality on the energetics and kinetics of radical initiated thiol-ene click chemistry has been studied computationally at the CBS-QB3 level. Relative energetics (ΔH°, ΔH(++), ΔG°, ΔG(++)) have been determined for all stationary points along the step-growth mechanism of thiol-ene reactions between methyl mercaptan and a series of 12 alkenes: propene, methyl vinyl ether, methyl allyl ether, norbornene, acrylonitrile, methyl acrylate, butadiene, methyl(vinyl)silanediamine, methyl crotonate, dimethyl fumarate, styrene, and maleimide. Electronic structure calculations reveal the underlying factors that control activation barriers for propagation and chain-transfer processes of the step-growth mechanism. Results are further extended to predict rate constants for forward and reverse propagation and chain-transfer steps (k(P), k(-P), k(CT), k(-CT)) and used to model overall reaction kinetics. A relationship between alkene structure and reactivity in thiol-ene reactions is derived from the results of kinetic modeling and can be directly related to the relative energetics of stationary points obtained from electronic structure calculations. The results predict the order of reactivity of alkenes and have broad implications for the use and applications of thiol-ene click chemistry.

ChemInform Abstract: Conformational Equilibrium in Methyl Allyl Ether

Abstract The microwave spectrum of methyl allyl ether has been investigated in the frequency range 28–40 GHz. The rotational spectra of two conformers have been assigned. On the basis of the obtained rotational constants it was easy to assign the structural configuration for one of them (oxygen atom syn , methyl group trans ), while for the second conformer they were in agreement with the trial values of three different configurations. Nevertheless, after that several A - E splittings due to the methyl group internal rotation have been measured; it appeared that they could have matched only the conformer with the oxygen atom skew with respect to the CC bond, and with the methyl group gauche ( inner ) with respect to the CC bond. The methyl group barrier to internal rotation and the dipole moments have been determined for both conformers.

ChemInform Abstract: Laser-Powered Homogeneous Pyrolysis of 1,1-Dimethyl-1-silacyclobutane in the Presence of Some Common Monomers.

Abstract Laser-induced homogeneous pyrolysis of 1,1-dimethyl-1-silacyclobutane yields 1,1,3,3-tetramethyl-1,3-disilacyclobutane and ethene as major products. In the presence of vinyl acetate, allyl methyl ether, acrolein, methyl vinyl ether, methyl acrylate or methyl methacrylate, the intermediate dimethylsilene is trapped by these monomers, or by products of their thermal decomposition, to yield both volatile and viscous or solid organosilicon compounds. The mode of formation of these products is discussed. Ethoxytrimethylsilane is judged to arise from addition of trimethylsilanol to ethene, and this was confirmed in independent thermal initiation of this reaction. Dimethylsilene is suggested to react with unsaturated methyl ethers to yield methoxytrimethylsilane and to undergo copolymerization with methyl acrylate.

Stereochemistry of Intermolecular Oxypalladation: PdII-Catalyzed 1,3-Chirality Transfer Reaction of Chiral Allylic Alcohol with Methanol

The intermolecular oxypalladation of chiral nonracemic allylic alcohols (S)-1, (R)-1, and (R)-3 in methanol gave chiral nonracemic methyl allyl ethers (S)-2 and/or (R)-2 with excellent selectivity. The reaction induced the 1,3-chirality transfer to give syn-S(N)2' product exclusively through syn oxypalladation. On the other hand, the anti-S(N)2' product was produced in 20-33% in THF, toluene, and CH2Cl2 and predominantly in CH3CN. The pi-olefin-Pd complexes I and II are proposed as important intermediates to explain the syn- and anti-oxypalladation pathways. The byproduct 9 was formed through the second syn-oxypalladation from the methyl allyl ether 2, though the rate of this second reaction was far slower than that of allylic alcohol.

Novel perfluoroalkylated oligo(oxyethylene) methyl ethers with high hemocompatibility and excellent co-emulsifying properties for potential biomedical uses

Two series of novel perfluoroalkylated amphiphilic compounds were synthesized from monomethyl ethers of mono-, di- and tri-(oxyethylene) glycols. The first series CH 3(OCH 2CH 2) n OCH 2CH(OH)CH 2–CF 2(CF 2CF 2) n CF 3 ( n = 1–3) bearing the hydroxy group at the spacer between hydrophilic and hydrophobic parts was prepared by the reactions of the monomethyl ethers with 2-(perfluoroalkylmethyl)oxiranes in 76–97% yields. The second series CH 3(OCH 2CH 2) n OCH 2CH 2CH 2–CF 2(CF 2CF 2) n CF 3 ( n = 1–3) possessing the non-hydroxylated spacer was synthesized from allyl methyl ethers of oligo(oxyethylene) glycols using radical additions of perfluoroalkyl iodides and subsequent selective reductions of the C–I bond in the adducts in overall yields of 23–69%. Some of the novel amphiphilic compounds displayed very low hemolytic activity to erythrocytes and excellent co-emulsifying properties on testing on perfluorodecalin/Pluronic F-68 microemulsions. 1- O-(2-Hydroxy-4,4,5,5,6,6,7,7,8,8,9,9,9-tridecafluorononyl)- d-xylitol was prepared by a novelized synthesis and employed as a standard compound in the testing.

Differentiation of isomeric allylic alkenyl methyl ethers by Raman spectroscopy

The Raman spectra of several pairs of alkenyl methyl ethers of general structure R 1R 2C CR 5C(R 3R 4)OCH 3 and R 1R 2C(OCH 3)C(R 5) CR 3R 4 (R 1, R 2, R 3, R 4, R 5 = H or C n H 2 n+1 , n = 1–3) are reported and discussed, with a view to establishing whether Raman spectroscopy offers a viable means of distinguishing between these isomeric unsaturated species. Key bands associated with the ν(sp 2C H) and ν(C C) stretching modes are found to be particularly useful in this connection: R 1R 2C CHCH 2OCH 3 and R 1R 2C(OCH 3)CH CH 2 ethers (R 1, R 2 = CH 3, C 2H 5) are easily distinguished on this basis. Differentiation of their lower homologues, R 1CH CHCH 2OCH 3 and R 1CH(OCH 3)CH CH 2 (R 1 = CH 3, C 2H 5, C 3H 7), by similar means is also quite straightforward, even in cases where cis and trans isomers are possible. Pairs of isomeric ethers, such as CH 3CH C(CH 3)CH 2OCH 3 and CH 3CH(OCH 3)C(CH 3) CH 2, in which the structural differences are more subtle, may also be distinguished with care. Deductions based on bands ascribed to the stretching vibrations are usually confirmed by consideration of the signals associated with the corresponding δ(sp 2C H) deformation vibrations. Even C 2H 5CH CHCH(C 3H 7)OCH 3 and C 3H 7CH CHCH(C 2H 5)OCH 3 are found to have distinctive Raman spectra, but differentiation of these closely related isomers requires additional consideration of the low wavenumber region.

Synthesis and ionic conductivity of mixed substituted polysiloxanes with oligoethyleneoxy and cyclic carbonate substituents

New comb polysiloxanes with mixed substituents were synthesized by hydrosilylation of PMHS with 4-allyloxymethyl-[1,3]dioxolan-2-one and tri(ethylene glycol) allyl methyl ether (AMPEO3). The effect of the incorporation of carbonate groups on ionic transport, viscosity and thermal properties has been investigated. When doped with lithium bis(trifluorosulfonyl) imide, LiTFSI, the mixed substituted polysiloxane polymers with varying carbonate content all exhibited conductivity higher than those for the polysiloxanes with pure carbonate or pure oligoethyleneoxy substituents. The maximum ambient conductivity in this series was 1.62× 10−4 S/cm, occurring for the polymer containing 8.5% polar carbonate groups at a doping level of EO/LiTFSI = 15. The impedance measurement results showed that polymers containing larger amounts of carbonate groups exhibited lower conductivity, probably because of their increased viscosity and higher glass transition temperature. The conduction mechanism for these new comb polymers obeys free volume theory, as indicated by conductivity data fit to the VTF equation.

Methyl allyl ether formation in plants: novel S-adenosyl l-methionine:coniferyl alcohol 9-O-methyltransferase from suspension cultures of three Linum species

A novel 41 kDa methyltransferase displaying high regiospecificity towards the allylic hydroxyl moiety of coniferyl alcohol was cloned from suspension cultures of Linum nodiflorum L. and expressed in E. coli. The apparent K (m) for coniferyl alcohol is 7.23 microM with a V (max) of 707.5 pkat mg(-1) protein at 30 degrees C, whereas the K (m) for the co-substrate S-adenosyl-L-methionine is 18.5 microM. Structure-function relationship studies revealed stringent structure requirements. Even minor substructure deviations as the side-chain saturation or changes in the phenyl ring substitution result in activities decreased by 75-90%. Crotyl and allyl alcohols are not substrates, confirming that the aromatic ring itself is indispensable, and solely the derivatives with a C(3) side-chain are accepted. The enzyme shares only similarities under 46% on amino acid level with other known methyltransferases. The designated reaction product, coniferyl alcohol 9-methyl ether, could be detected in suspension cells. The highest content of up to 0.02% of the dry mass is concurrent with an increase of the specific enzyme activity that reaches its maximum of 3.94 pkat mg(-1) on day 6 of the culture period. Transcript levels estimated by semi-quantitative RT-PCR remain constant until day 6 and recede thereafter. The corresponding methyltransferase from Linum flavum L. differs mainly by one short variable fragment. Biochemical characterization revealed a higher catalytic efficiency and a slightly broader substrate plasticity together with a lower sensitivity to the presence of Zn(2+), Cu(2+) and Co(2+). This is to our knowledge the first report of a regiospecific allylic O-methylation of phenylpropanoids in plants.

Reaction of the Acetals with TESOTf−Base Combination; Speculation of the Intermediates and Efficient Mixed Acetal Formation

We report here unexpected highly chemoselective deprotection of the acetals from aldehydes. Treatment of acetal compounds from aldehydes with TESOTf-2,6-lutidine or TESOTf-2,4,6-collidine in CH2Cl2 at 0 degrees C followed by H2O workup at the same temperature caused the conversion of the acetal functions to aldehyde functions. The reaction had generality and was applied to many acetal compounds. Study using various bases revealed the reaction and reached the best combination of TESOTf-base. It was very mild and highly chemoselective and proceeded under weakly basic conditions. Then, many functional groups such as allyl alcohol, silyl ether, acetate, methyl ether, triphenylmethyl (Tr) ether, 1,3-dithiolane, methyl ester, and tert-butyl ester could survive under these conditions. Furthermore, this methodology could selectively deprotect the acetals in the presence of ketals as the most characteristic feature, although this chemoselectivity is difficult to achieve by other previously reported methods. A detailed study of the reaction including MS and NMR studies revealed the reaction mechanism for determining the structures of the intermediates, pyridinium-type salts. These intermediates had a weak electrophilicity and were successfully applied to the efficient formation of the mixed acetals in high yields.

Synthesis of Cross‐Linked Comb Polysiloxane for Polymer Electrolyte Membranes

AbstractSummary: A series of comb‐like polysiloxanes was prepared as the base polymer for solvent‐free polymer electrolyte membranes. Hydrosilylation of poly(methylhydrosiloxane) (PMHS) was used to substitute hydrogen by the two types of side groups tetraethylene glycol allyl methyl ether and allyltrimethoxysilane (ATMS) with varying molar ratios between 5 and 40 mol‐% ATMS. The ATMS side groups served to cross‐link as‐prepared polymer electrolyte membranes after dissolving lithium trifluoromethylsulfonate (triflate) or lithium bis(trifluoromethylsulfonyl)imide. The ionic conductivities of these salt‐in‐polymer membranes prepared with a constant concentration of 10 wt.‐% lithium triflate showed a maximum conductivity of 4.6 × 10−5 S · cm−1 at 30 °C for 10 mol‐% ATMS substitution. In another series of experiments with the ATMS substitution held constant at 10 mol‐%, the salt concentration was varied yielding a maximum conductivity of 1.4 × 10−4 S · cm−1 at 30 °C for 12.5 wt.‐% lithium triflate. magnified image

CpRu(IV)(π‐C3H5)(2‐quinolinecarboxylato)]PF6 Complex: A Robust Catalyst for the Cleavage and Formation of Allyl Ethers

AbstractA facile and efficient method for the quantitative synthesis of [CpRu(IV)(π‐C3H5)(2‐quinolinecarboxylato)]PF6 from [CpRu(CH3CN)3]PF6, 2‐quinolinecarboxylic acid, and 2‐propen‐1‐ol has been established. The cationic Ru(IV) complex is air‐ and moisture‐stable, and can be stored in a vial for at least six months. This complex realizes a simple and easy operation for both the deallylation of allyl ethers in methanol and the dehydrative allylation of alcohols. Furthermore, with removal of the volatile allyl methyl ether co‐product from the reaction system, the robust catalyst can attain a turnover of 10000 cycles of allyl ether cleavage.

Stereoselectivity of Intramolecular SN‘ Cyclizations of Alkyllithium Reagents on Methoxy Alkenes

The cyclization of alkyllithium reagents onto methoxy alkenes has been investigated. The alkyllithium reagent was generated by reductive lithiation of an alkyl nitrile. In an unbiased substrate, a methoxy leaving group attached to a stereogenic secondary carbon atom led to the cyclization product with high optical purity. The configuration of the product demonstrated that the cyclization had proceeded with high syn-S(N)' selectivity. Previously we have shown that 2-lithiotetrahydropyran reagents cyclize to form spirocycles with the alkene cis to the pyran oxygen. Substrates were prepared to evaluate the importance of the configuration of the secondary allyl methyl ether against the alpha-alkoxy alkyllithium configuration. In the matched case (cyano acetal 38), a very selective cyclization ensued. In the mismatched case (cyano acetal 39), the spiro ether selectivity dominated. The syn-S(N)' selectivity overcame the normal E selectivity in the cyclization and accounted for the major product, Z-alkene 45. Thus the stereochemical preference in these alkyllithium cyclizations is dominated by the spiroether effect, followed by the syn-S(N)' selectivity and finally the preference for E-alkene formation.

The polymer electrolyte based on polysiloxane containing both alkyl cyanide and oligo ethylene oxide pendants

The monomers, (3-cyanopropyl) methylsiloxane cyclics (D4CN) and (3-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)propyl) methylsiloxane cyclics (D4TEG) were prepared by a hydrosilylation reaction of 2,4,6,8-tetramethylcyclotetrasiloxane (D4H) with allyl cyanide and tri(ethylene glycol) methyl allyl ether (allyl TEG), respectively, in toluene using a platinum(0)-1,3-divinyl-1,1,3,3-tetramethyl disiloxane complex as the catalyst. The new crosslinkable polymers with alkyl cyanide and ethylene oxide groups as the pendent were synthesized by ring opening polymerization and characterized by GPC and 1H NMR. And then, the crosslinked solid polymer electrolyte was prepared by UV radiation curing. The conductivities of samples were measured by impedance spectroscopy using an indium–tin oxide (ITO) electrode. As the results, the maximum ionic conductivities of the polymer were 1.15 × 10 −5 S cm −1 at 20 °C and 1 × 10 −4 S cm −1 at 60 °C. The electrolyte was stable electrochemically to 5 V versus Li +/Li at room temperature.

Mechanism studies on the CSI reaction with allyl ethers by varying p-substituent.

We examined the effect of p-substituents in p-substituted cinnamyl methyl ethers and 1-(p-substituted phenyl)allyl methyl ethers with CSI, and confirmed that the CSI reaction of allyl ethers (p-substituted ethers) is a competitive reaction of S(N)i and S(N)1 mechanism according to the stability of the carbocation. And, the only terminal allylic amine was obtained through the migration reaction in thermodynamic reaction condition.

Synthesis and ionic conductivity of comb-like polysiloxanes with Pendant oligo(oxyethy1ene) side chains and quaternary ammoniurn groups

A series of novel comb-like polysiloxanes with oligo(oxyethy1ene) side chains and quaternary ammonium groups, has been synthesized by hydrosilylation of poly(methylhydrosi1oxane) with poly(ethy1ene glycol) allyl methyl ether and N,N-dimethylallylamine, followed by quaternization with methyl iodide. The glass transition temperature of these solvent-free electrolytes was measured and found to be dependent on the content of quaternary ammonium side groups anchored to the polysiloxane backbone. The influence of quaternary ammonium group content and temperature on the ionic conductivity has been investigated. A maximum conductivity of 1.57 × 10−5 S cm−1 at 25 °C was achieved for a poiysiloxane containing 30 % quaternary ammonium side groups. The temperature dependence of the ionic conductivity shows the “Vogel-Tammann-Fulcher” (VTF) behavior. The values of the VTF Parameters were calculated.

Palladium-catalyzed isobenzofuran generation under neutral conditions via oxidative addition to lactol methyl ether.

A novel method for generation of isobenzofuran is developed from lactol methyl ether using palladium catalysts. This reaction can be carried out under neutral conditions and hence improves on the precedent methods under acidic or basic conditions and at high temperatures. Furthermore, this Pd-catalyzed isobenzofuran generation suggests the involvement of oxidative addition of Pd catalyst into benzylic or allylic methyl ethers. [reaction: see text]

Synthesis of Methoxynor Polyisoprenoid Alcohols by Alkylation of (3-Methoxyallyl)lithium Reagents

A series of six methyl enol ether analogs 8-13 of geraniol, (E,E)-farnesol, and (E,E,E)-geranylgeraniol was synthesized from a group of three allylic methyl ethers and three allylic chlorides. Lithiation of the 1-methyl-, or 1-alkenylvinyl ethers with sec-butyllithium at -78 °C followed by alkylations of the resulting (Z)-(3-methoxyallyl)lithium reagents afforded the six possible Z-configured(trans) methoxynor polyprenyl benzyl ethers bearing the methoxy substituent at the internal and terminal double bonds with high Z/E ratios (5 : 1-31 : 1) and 47-80% yields. Reductive cleavage of the benzyl groups with lithium in liquid ammonia gave the corresponding methoxynor polyprenols. 11-Methoxy-18-nor and 7-methoxy-19-nor geranylgeraniols (13 and 12) were converted to the corresponding diphosphates, 7 and 32, by the Poulter displacement method. The stability of the enol ether in 7 in aqueous solution at pH 8 was verified by NMR analyses. The diphosphates of the methoxynor polyprenols may prove useful as substrate analogs for terpene synthases to capture transient intermediates in cyclization reactions catalyzed by these enzymes.

Electron energy loss and dissociative electron attachment spectroscopy of methyl vinyl ether and related compounds

The triplet and singlet excited states of methyl vinyl ether have been characterized by electron energy loss spectroscopy and multireference density functional theory with configuration interaction (DFT/MRCI). The electron attachment energy was determined from the excitation functions for vibrational excitation to be 2.3 eV. Dissociative electron attachment spectra have been measured with a mass spectrometer having a trochoidal monochromator in the incident electron beam. Fragment anion bands peaking at 3 eV, 6.5 eV and 9.5 eV have been found in methyl vinyl ether. The first band is assigned to the 2(π∗) shape resonance, the second band to a resonance where an electron is loosely bound by dipole and polarization forces to the target molecule in its valence excited 1(π, π∗) state, and the third band to Feshbach resonances with occupation of Rydberg orbitals. CH 3O − and H 2CC − are formed at 3 eV, CH 3O − and HCC − at 6.5 and 9.5 eV. The fragmentation pattern of ethyl vinyl ether at 3 eV is similar, yielding ethanolate and vinylidene anions, but with the unexpected addition of the deprotonated acetaldehyde anion CH 2CHO −. The fragmentation patterns of methyl allyl ether and benzyl methyl ether are dominated by the methanolate anions with high intensity, indicating that dissociation of C–O bond in unsaturated ethers is much faster if this bond does not lie in the plane of the π system.

Reactions of metastable ionized γ, γ-dialkylallyl methyl ethers: relative rates for elimination of alkyl radicals by formal γ-cleavage

The reactions of seven metastable ionised allylic alkenyl methyl ethers of general structure, R 1R 2C= CHCH 2OCH 3 + [R 1=CH 3, R 2=C 2H 5, n-C 3H 7, n-C 6H 13, or iso-C 3H 7; R 1=C 2H 5, R 2= n-C 3H 7 or iso-C 3H 7; R 1 = n-C 3H 7, R 2 = n-C 4H 9] with two different γ-alkyl substituents are reported and discussed. Two common reactions are observed: loss of a molecule of methanol or elimination of an alkyl radical. The second fragmentation is interpretable by a mechanism in which two consecutive 1,2-hydrogen shifts lead to an ionised enol ether, R 1R 2CHCH  CHOCH 3 +, which then undergoes γ-cleavage to give either R 1CH  CHCH  O +CH 3 or R 2CH  CHCH  O +CH 3. Competition experiments reveal that the relative rate of alkyl radical loss from these metastable radical-cations follows the order (CH 3) 2CH· > CH 3CH 2 · > CH 3CH 2CH 2 · ≥ CH 3CH 2CH 2CH 2 ·⪢ CH 3 · Metastable ionised ethers containing a γ-isopropyl group differ from their isomers with an n-propyl substituent in expelling propane at an appreciable rate. A unique process apparently involving loss of a neutral with a mass of 74 Da is observed from metastable CH 3CH 2CH 2CH 2CH 2CH 2(CH 3)C  CHCH 2OCH 3 +, this fragmentation is attributed to consecutive elimination of two species, C 3H 6 followed by CH 3OH, rather than direct expulsion of C 4H 10O.