Chemoselective hydrosilations. I. Synthesis and photopolymerization of 1-propenyl ether functionalized siloxanes

The synthesis of 1-propenyl ether-functionalized siloxanes (PFS) has been achieved by the controlled, rhodium-catalyzed, chemoselective hydrosilation of 1-allyloxy-4(1-propen-oxy) butane with various H-functional siloxanes. It was shown that the hydrosilation pro-ceeds exclusively at the allyl ether group of 1-allyloxy-4(1-propenoxy) butane without par-ticipation at the 1-propenyl ether group. The photoinduced cationic polymerization of these monomers was studied using various analytical techniques and found to take place very rapidly. © 1995 John Wiley & Sons, Inc.     

SYNTHESIS OF ALKYL AND ARYL 1-PROPENYL ETHER MONOMERS: A NEW APPROACH

A new, convenient synthesis of alkyl and aryl 1-propenyl ether monomers in good to excellent yields has been developed. Alkyl and aryl allyl ethers can be smoothly isomerized to the desired 1-propenyl ethers by refluxing in a basic ethanolic solution containing pentacarbonyliron as a catalyst. A simplified two-step, one-pot procedure has also been developed which consists of combining an alcohol with allyl bromide in the presence of base and then adding pentacarbonyliron to isomerize the in-situ generated allyl ether to directly give the 1-propenyl ether. Good yields of alkyl 1-propenyl ethers were obtained using this process. Factors affecting the isomerization reaction were investigated and a mechanism was proposed.     

Phase-transfer catalyzed synthesis of 2-propenyl esters of carboxylic acids

Summary The tetrabutylammonium bromide catalyzed esterification of salts of carboxylic acids1 a–e with 2-propenyl halides2 a,b is described.

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Phasentransferkatalysierte Synthese von 2-Propenylestern von Carbonsäuren (Kurze Mitt.)

Zusammenfassung Es wird die tetrabutylammoniumkatalysierte Veresterung von Carbonsäuresalzen1 a–e mit 2-propenylhalogeniden2 a,b beschrieben

     

The synthesis of 4-(2,6,10-trimethyl-1,3,5,9-undecatetraenyl)benzoic acid based on alkoxy alkene-acetal condensation

4-(2,6,10-Trimethyl-1,3,5,9-undecatetraenyl)benzoic acid (1) was synthesized starting from ethyl 4-formylbenzoate (2) and linalool. The key intermediate, ethyl 4-(2-methyl-3-oxo-1-propenyl)benzoate (5), was obtained by the addition of diethyl acetal (3), prepared from2, to ethyl 1-propenyl ether (EPE) followed by the hydrolysis of the resulting adduct.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 914–915, May, 1993.     

Synthesis and Studies on Surface Active Water Soluble Derivatives of Siloxane Oligomers

Abstract

We report the synthesis of cationic water-soluble siloxanes by reacting aminosiloxanes with dimethyl, n-dodecyl 3-chloro-2-hy-droxypropyl quaternary ammonium iodide (DDCQA). Tetramethyl disiloxane on hydrosilation with allyl amine in the presence of hex-achloroplatinic acid/IPA gave bis(3-aminopropyl) octamethyltetra-siloxane. In addition, formation of Si-H containing oligomeric siloxanes were detected during this reaction and the extent of formation of the oligomers was found to depend upon the concentration of platinum. The oligomerization reaction was explained by dehydrogenative coupling of Si-H groups in the presence of platinum catalyst. A plausible mechanism for formation of aminosiloxane and the Si-H oligomers were proposed. Alternatively, cyclic Si -H containing siloxanes on polymerization using butyl lithium gave oligomeric Si-H containing siloxanes, which were hydrosilated to give aminosiloxanes. The quaternary aminosiloxanes synthesized showed lowering in surface tension of water to 26 mN/m.     

New synthetic approach to 8-allyltheophylline

Summary The synthesis of 8-allyltheophylline (8) from 5,6-diamino-1,3-dimethyluracil (1) and 3-butenoic acid byTraube's methodvia 6-amino-5-(3-butenoylamino)-1,3-dimethyluracil (2) failed because an attempted alkaline cyclization of the intermediate2 afforded (E)-8-(1-propenyl)-theophylline (3) under rearrangement of the terminal C=C bond. Therefore, the cyclodehydratation of 6-(3-butenylamino)-5-nitroso-1,3-dimethyluracil (7), available from 6-chloro-1,3-dimethyluracil (5)via 6-(3-butenylamino) derivative6 has to be used for obtaining the required product8.

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Ein neuer synthetischer Zugang zu 8-Allyltheophyllin

Zusammenfassung 8-Allyltheophyllin (8) kann nicht mittels derTraube-Synthese aus 5,6-Diamino-1,3-dimethyluracil und 3-Butensäurevia 6-Amino-5-(3-butenoylamino)-1,3-dimethyluracil (2) hergestellt werden, wei bei der alkalischen Cyclisierung des Zwischenproduktes2 Umlagerung der terminalen C=C-Doppelbindung unter Bildung von (E)-8-(1-Propenyl)theophyllin (3) erfolgt. Zur Darstellung der Verbindung8 muss man daher die Dehydratationscyclisierung von 6-(3-Butenylamino)-5-nitroso-1,3-dimethyluracil (7) anwenden. Letzteres ist aus 6-Chloro-1,3-dimethyluracil über das 6-(3-Butenylamino)-Derivat6 zugänglich.

     

Synthesis and photopolymerization of 1-propenyl glycidyl ether

The ambifunctional monomer, 1-propenyl glycidyl ether, was prepared from allyl glycidyl ether, by a ruthenium-catalyzed isomerization reaction in high yield. 1-Propenyl glycidyl ether undergoes facile photoinduced cationic polymerization to yield a crosslinked polymer. The structure of this polymer was studied using ¹H- and, ¹³C-NMR spectroscopies and employing well-characterized related polymers as models. The model polymers were prepared by the cationic polymerization of allyl glycidyl ether with BF₃OEt₂ followed by isomerization of the pendant allyl groups by a ruthenium catalyst. Subsequently, the resulting polyether-bearing pendant 1-propenyl ether groups was subjected to a diaryliodonium salt-photoinitiated polymerization. A comparison of the spectra of the polymers indicated the presence of cyclic acetal units in the polymer backbone. © 1994 John Wiley & Sons, Inc.     

Synthesis and properties of vinyl‐terminated and silicon‐containing polysulfones and polyketones

4‐Fluorophenylsulfonylphenyl‐terminated polysulfone and 4‐fluorobenzoylphenyl ketone were prepared with bisphenol A and an excess of bis‐(4‐fluorophenyl)sulfone or 4,4′‐difluorobenzophenone, respectively, at 160 °C using potassium carbonate in N,N‐dimethylacetamide. The resulting polymers were reacted with 4‐hydroxystyrene to synthesize vinyl‐terminated polysulfones and ketones. The silicon‐containing polysulfones and ketones were prepared from the vinyl‐terminated polymer precursor and various H‐functional silanes or siloxanes. The synthesis of silicon‐containing polymers was achieved by hydrosilation with a rhodium catalyst. It was shown that the hydrosilation reaction proceeds with 55:45 chemoselectivity. The resulting polymers were investigated by ¹H NMR spectroscopy, DSC, and thermogravimetric analysis. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2937–2942, 2001     

Synthesis and characterization of oligocyclosiloxanes via the hydrosilation of vinylsilanes and vinylsiloxanes with heptamethylcyclotetrasiloxane

The preparation of oligocyclosiloxanes via hydrosilation reactions has been investigated. Hydrosilation reactions employing heptamethylcyclotetrasiloxane and vinyl-containing silanes and siloxanes yielded a variety of oligocyclosiloxanes with various numbers of cyclosiloxane rings connected through tri-, tetra-, penta-, hexa-, hepta-, or octafunctional junctions. The oligocyclosiloxanes were characterized by gas chromatography, IR spectroscopy, ²⁹Si-, ¹H-, and ¹³C-NMR spectroscopy, elemental analysis, and vapor phase osmometry. The polycyclics were redistributed with hexamethyldisiloxane and the resulting fragments analyzed by gas chromatography. All results were consistent with the formation of isomeric oligocyclosiloxanes due to a lack of absolute regioselectivity of the hydrosilation reaction. © 1993 John Wiley & Sons, Inc.     

Syntheses of folic acid models, 6-(N-acylarylamino)methyllumazines

Folic acid models, 1,3-dimethyl-6-(N-acylarylamino)methyllumazines 9 , were synthesized from 6-bromomethyl-1,3-dimethyllumazine ( 6 ), which was derived from 5,6-diamino-1,3-dimethyluracil ( 1 ) by the condensation with 1,3-dihydroxyacetone, followed by bromination. The bromide 6 was also prepared by the cycloaddition between 3,6,8-trioxo-5,7-dimethyl-5,6,7,8-tetrahydro-3H-pyrimido[5,4-c][1,2,5]oxadiazine ( 4 ) and 1-propenyl trimethylsilyl ether followed by bromination. The folic acid models 9 were also directly synthesized from the oxadiazine 4 and 3-(N-acylaryl)amino-1-propenyl trimethylsilyl ether 8 by cycloaddition.     

SYNTHESIS OF POLYPROPYLENE-POLY(METH)ACRYLATE BLOCK COPOLYMERS USING METALLOCENE CATALYZED PROCESSES AND SUBSEQUENT ATOM TRANSFER RADICAL POLYMERIZATION

ABSTRACT

The synthesis of block copolymers containing low molar mass polypropylene and poly(meth)acrylates is reported. Vinyl-terminated polypropylene (M_n SEC=3,100; M_w/M_n=1.45) was used to prepare a macroinitiator for atom transfer radical polymerization (ATRP) via hydrosilation with 1-(2-bromoisobutyryloxy)propyl-tetramethyldisiloxane. Polar segments were then incorporated to polypropylene by chain extension using either methyl methacrylate, or n-butyl acrylate. While blocking efficiency was limited in this system, well-defined PP-b-PMMA (M_n=22,220; M_w/M_n=1.14) was obtained by extraction of unreacted polypropylene with diethyl ether.     

o-quinone methides 2. Stereoselectivity in cycloaddition reactions of o-quinone methides with vinyl ethers

Cycloaddition reactions between vinyl ethers 3 and $\text{o}$-quinone methides 2, thermally generated from 2-hydroxybenzyl alcohols 1, have been studied. The structure and conformational preferences of the 4-substituted 2-ethoxy-(2,3)-dihydro-2$\text{H}$-benzopyrans 4–9 obtained, which show new interesting features, are discussed together with competitive kinetic data. The cycloaddition process is concerted and involves $\text{o}$-quinone methides in the $\text{E}$-configuration. The OEt-$\text{endo}$ transition state seems to be preferred with ethyl vinyl ether and $\text{Z}$-1-propenyl ethyl ether, whereas with $\text{E}$-1-propenyl ethyl ether the stereoselectivity of the cycloaddition process depends on substituents on the methylene group of the starting alcohol 1. These results are discussed in terms of $\text{endo}$ and $\text{exo}$ preference of the propenyl ether methyl group.     

A study of the Claisen rearrangement of 7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one derivatives

Summary The Claisen rearrangement of 7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one (2 a) gave 7-hydroxy-8-(1-phenyl-2-propenyl)-3-phenyl-(4H)-1-benzopyran-4-one (3 a) and 2,3-dihydro-2,6-diphenyl-3-methyl-(7H)furo[2,3-h]-1-benzopyran-7-one (7 a). 2-Methyl-7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one (2 b) afforded4 b and7 b. 8-Methyl-7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one (12) gave only the alkali soluble product 7-hydroxy-8-methyl-6-(1-phenyl-2-propenyl)-3-phenyl-(4H)-1-benzopyran-4-one (13).3 a,4 b, and13 were further cyclized in acidic medium to9 a,10 b, and14 followed by dehydrogenation.This paper is dedicated to Dr. F. M. Dean, Department of Organic Chemistry, Robert Robinson Laboratories, University of Liverpool, Liverpool, U. K., on his retirement     

Study of the Stabilization of Polyvinyl Chloride) by Using Model Molecules. VI. Mechanism of Reactions of Aminocrotonate Esters

The mechanism of reaction of the β-aminocrotonate of butanediol (βACB) with 4-chloro-2-hexene (4C2H), a model compound for the allylic chlorine in polyvinyl chloride), was studied in THF or dichloroethane at 60°C by gas and liquid chromatography. The reaction, which needs ZnCl₂ as a catalyst, leads to substitution products through the primary amine group and the hydrogen atom of the trisubstituted double bond. βACB reacts with HCl to give NH4Cl and a set of complex organic products. NH₄Cl and the substitution products are able to complex ZnCl, inhibiting its catalytic activity. In combination with other stabilizers, βACB strongly induces the substitution reaction versus the dehydro-chlorination. In the polymer at 190°C, it increases very much the time of action of the stabilizers; it acts as an HC1 acceptor but also it may be substituted on the polymer even without catalysts. Synergistic effects are observed with epoxy compounds or indole derivatives.     

Transition metal-catalyzed tandem isomerization and cationic polymerization of allyl ethers. II. Structural and mechanistic studies

In the presence of organosilanes, dicobalt octacarbonyl catalyzes the polymerization of alkyl allyl ethers to give high molecular weight polymers. This article reports the results of a detailed mechanistic study of this new polymerization reaction. The evidence obtained in this study supports a stepwise process involving first, the reaction of dicobalt octacarbonyl with an organosilane to form HCo(CO)₄ and R₃SiCo(CO)₄. In subsequent steps, HCo(CO)₄ isomerizes the allyl ether to a 1-propenyl ether and then this compound is polymerized by the formal transfer of a silyl cation from R₃SiCo(CO)₄. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1985–1997, 1997     

Synthesis and photochemical reaction of novel p-alkylcalix[n]arene derivatives containing cationically polymerizable groups

New photoreactive p-methylcalix[6]arene (MCA) derivatives containing cationically polymerizable groups such as propargyl ether (calixarene 1), allyl ether (calixarene 2), and ethoxy vinyl ether (calixarene 3) groups were synthesized with 80, 74, and 84% yields by the substitution reaction of MCA with propargyl bromide, allyl bromide, and 2-chloroethyl vinyl ether (CEVE), respectively, in the presence of either potassium hydroxide or sodium hydride by using tetrabutylammonium bromide (TBAB) as a phase transfer catalyst (PTC). The p-tert-butylcalix[8]arene (BCA) derivative containing ethoxy vinyl ether groups (calixarene 4) was also synthesized in 83% yield by the substitution reaction of BCA with CEVE by using sodium hydride as a base and TBAB as a PTC. The MCA derivative containing 1-propenyl ether groups (calixarene 5) was synthesized in 80% yield by the isomerization of calixarene 2, which contained allyl ether groups, by using potassium tert-buthoxide as a catalyst. The photochemical reactions of carixarene 1, 3, 4, 5, and 6 were examined with certain photoacid generators in the film state. In this reaction system, calixarene 3 containing ethoxy vinyl ether groups showed the highest photochemical reactivity when bis-[4-(diphenylsulfonio)phenyl]sulfide bis(hexafluorophosphate) (DPSP) was used as the catalyst. On the other hand, calixarene 1 containing propargyl ether groups had the highest photochemical reactivity when 4-morpholino-2,5-dibuthoxybenzenediazonium hexafluorophosphate (MDBZ) was used as the catalyst. It was also found that the prepared carixarene derivatives containing cationically polymerizable groups such as propargyl, allyl, vinyl, and also 1-propenyl ethers have good thermal stability. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1805–1814, 1999     

Cationic photoinitiated copolymerization of 1-propenyl-vinyl ether systems

A kinetic investigation of the photoinitiated cationic copolymerization of 1-propenyl ethers with vinyl ethers monomers was performed by using FT-IR and 1H-NMR analysis. FT-IR results, obtained in bulk, indicate a higher reactivity of the vinyl ether with respect to the 1-propenyl ether double bond. 1H-NMR analysis, in CDCl₃ solution, confirms these results which agree with the literature data concerning monofunctional systems. The properties of the UV cured copolymerization products are investigated by DMTA analysis and discussed on the basis of the kinetic investigation results.     

Structure Determination of an Unusual [2.2]paracyclophane Derivative by NMR Spectroscopy

Our ongoing study on cycloaddition reactions of dienes with different dienophiles afforded a great variety of derivatives with interesting molecular structures and electronic behavior. A new type of angularly annelated [2.2]paracyclophane (3) has been synthesize by the Diels–Alder reaction of 4-(2-propenyl[2.2]paracyclophane (1) and 1,4-benzoquinone (2) under high pressure conditions. The structure determination of this compound has been achieved by NMR measurements and semiempirical calculations.     

Kinetic studies of photopolymerization using real time FT-IR spectroscopy

The real time FT-IR (RT/FT-IR) technique has been recognized as a very vital tool to quantitatively study the curing parameters such as the effects of initiator (or catalyst) type and concentration, accelerator, stabilizer, irradiation wavelength, temperature, and curing environments. Herein, our results in studies of photoinduced polymerizations for adhesive and coating applications are reported. The photoinduced polymerizations studied included anionic and hydrosilation (a polyaddition polymerization) reactions. In photoinduced anionic polymerization our studies for ethyl cyanoacrylate polymerization are described. The effect of the concentration of photoinitiator and inhibitor on the ethyl cyanoacrylate polymerization kinetic rate will be discussed. In photoinduced catalytic hydrosilation reaction studies, the effects of the catalyst concentration and staging irradiation are disclosed. The hydrosilation reaction was monitored using a Si? H silicone hydride stretching band located at 2169 cm^?1. The cyanoacrylate polymerization was monitored using the C?C stretching band occurring at 1617 cm^?1. The hydrosilation conversion was completed with an appropriate formulation. For monofunctional cyanoacrylate monomer, the photoinduced conversion to straight chain polymer was approximately 85% for a 60 s period. The intrinsic rates of the reactions were calculated for kinetic comparisons. For very fast cyanoacrylate polymerization studies, new FT-IR kinetic software was used to collect 204 spectra/min. Some detailed experimental techniques and polymerization reaction mechanisms are also discussed. © 1993 John Wiley & Sons, Inc.