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1.
Leiv K. Sydnes Karl F. S. Alnes Natalia Erdogan 《Monatshefte für Chemie / Chemical Monthly》2005,54(9):1737-1749
Several 2-alkyl-1,1,2-tribromocyclopropanes were treated with sodium hydroxide and ethanol under phase-transfer conditions.
Ring opening gave mixtures of the corresponding acetylenic diethyl ketals and acetals. When the steric bulk of the alkyl substituent
was increased acetal formation dominated, and in the case of 1,1,2-tribromo-2-(tert-butyl)cyclopropane, the acetal was formed as the only product. 相似文献
2.
Summary. Treatment of a number of 2-substituted 1,1,2-tribromocyclopropanes with MeLi at −78°C gave the corresponding 1-bromocyclopropenes,
which were reacted with three cyclic dienes to yield the [4 + 2]-cycloadducts. Cycloaddition with 1,3-diphenylisobenzofuran
(DPIBF) gave the exo adducts, in most cases in excellent yield, whereas cyclopentadiene afforded endo adducts only, but in moderate yield. In most reactions with furan no adduct was formed, but two 1-bromocyclopropenes derivatives
with an aromatic side chain were exceptions and furnished mixtures of exo and endo adducts in moderate yields. 相似文献
3.
J. Guiot M.‐A. Nouze L. Sauguet B. Amduri B. Boutevin 《Journal of polymer science. Part A, Polymer chemistry》2005,43(5):917-935
The radical copolymerization of vinylidene fluoride (VDF) with 4‐bromo‐1,1,2‐trifluorobut‐1‐ene (C4Br) was examined. This bromofluorinated alkene was synthesized in three steps, which started with the addition of bromine to chlorotrifluoroethylene. In contrast to the ethylenation of 1,1‐difluoro‐1,2‐dibromochlorethane, which failed, that of 2‐chloro‐1,1,2‐trifluoro‐1,2‐dibromoethane was optimized and led to 2‐chloro‐1,1,2‐trifluoro‐1,4‐dibromobutane. The kinetics of the copolymerization of VDF with this brominated monomer initiated by t‐butyl peroxypivalate led to an assessment of the reactivity ratios, rVDF = 0.96 ± 0.67 and rC4Br = 0.09 ± 0.63, at 50 °C. The suspension copolymerization was also carried out, and the chemical modifications of the resulting bromo‐containing poly(vinylidene fluoride)s were attempted and consisted mainly of elimination or nucleophilic substitution of the bromine. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 917–935, 2005 相似文献
4.
GuillermoR. Labadie LilianaE. Luna RaquelM. Cravero Manuel Gonzlez‐Sierra 《Helvetica chimica acta》2006,89(11):2732-2737
The partial structure 2 of the bisketal‐type, tetracyclic saudin ( 1 ), an important natural product, was de novo synthesized. A key step was the Jones oxidation of the epoxide 3 , which gave rise to epoxide‐ring opening, followed by acetal hydrolysis, alcohol oxidation, and, finally, intramolecular acetal formation. The resulting key intermediate was finally oxidized to the target lactone 2 . 相似文献
5.
Andrew R. Wolff Ikuo Nozue Jim Maxka Robert West 《Journal of polymer science. Part A, Polymer chemistry》1988,26(3):701-712
The 29Si-NMR spectra are reported for poly(methylphenylsilylene), 1 , poly(1,1,2-trimethyl-2-phenyldisilene) 2 , two samples of poly(dimethylsilylene-co-phenylmethylsilylene), 3a and 3b , and poly(phenylmethylsilylene-co-n-hexylmethylsilylene), 4 . The spectra of 3a , 3b , and 4 indicate that these polymers contain blocklike regions with considerable segregation of RMeSi and PhMeSi groups. The spectrum of 2 shows no evidence for stereospecific polymerization. The preparation of 2 from 1,1,2-trimethyl-2-phenyldichlorosilane is also described. 相似文献
6.
By means of spectroscopic analysis, X-ray crystallography and chemical correlation the heartwood of Taiwan hemlock was found to contain compounds of sterols, carboxylic acids, 13-epimanool, o methoxyphenolics, coniferaldehyde, benzofuranoid neolignan, α-conidendrin, tsugacetal, isolariciresinol, secoisolariciresinol, matairesinol, hydroxymatairesinol and oxomatairesinol. Among them (+)-tsugacetal is a novel lignan acetal having an α-conidendrin related structure with the acetal methoxy group at the β-position. 相似文献
7.
The synthesis of N-[4-[2-(2,4-diamino-1,6-dihydro-6-oxo-5-pyrimidinyl)ethylamino]benzoyl]-L-glutamic acid ( 2 ), a two carbon analogue of 5-DACTHF ( 1 ) and an acyclic analogue of 5,6,7,8-tetrahydrofolic acid, is reported. The pyrimidinylacetaldehyde diethyl acetal 3 , which was prepared in 2-steps from 2-chloro acetaldehyde diethyl acetal, was converted to 2 in four steps. Compound 2 was less cytotoxic toward Detroit 98 or L cells than 5-DACTHF ( 1 ). 相似文献
8.
Xiaocui Liu Wenbo Ming Alexandra Friedrich Florian Kerner Todd B. Marder 《Angewandte Chemie (International ed. in English)》2020,59(1):304-309
We report herein the catalytic triboration of terminal alkynes with B2pin2 (bis(pinacolato)diboron) using readily available Cu(OAc)2 and PnBu3. Various 1,1,2‐triborylalkenes, a class of compounds that have been demonstrated to be potential matrix metalloproteinase (MMP‐2) inhibitors, were obtained directly in moderate to good yields. The process features mild reaction conditions, a broad substrate scope, and good functional group tolerance. This copper‐catalyzed reaction can be conducted on a gram scale to produce the corresponding 1,1,2‐triborylalkenes in modest yields. The utility of these products was demonstrated by further transformations of the C?B bonds to prepare gem‐dihaloborylalkenes (F, Cl, Br), monohaloborylalkenes (Cl, Br), and trans‐diaryldiborylalkenes, which serve as important synthons and have previously been challenging to prepare. 相似文献
9.
Ibrahim M. El-Deen 《中国化学》1999,17(4):391-397
3–(Pyrazol-5-yl)coumarin (3) was prepared from condensation of 3–(2′-formyl-l-chlorovinyl)-coumarin (1) with hydrazine hydrate at room temperature, followed by cyclyzation with base. Salicylaldazine was prepared from methoxylation of 1 to give acetal 7 , followed by condensation of 7 with hydrazine hydrate at 80°C: Treatment of acetal 7 with thiourea yielded the corresponding 4-substituted-2-thioxo-2H-pyrimidine[3, 4-b]-coumarin (12). 相似文献
10.
Bicyclic acetal derivatives of the type 3 were prepared based either on a dihydroxyaldehyde 5 or an oxiranebutanal 6 (cf. Scheme 2). Lewis acid catalyzed reaction of the bicyclic acetal with allyltrimethylsilane introduces the side chain (as yet unfunctionalized) and sets the stereogenic centers at the tetrahydro‐2H‐pyran ring of the pederin moiety. 相似文献
11.
Bromination, acylation, nitration, and metallation of imidazole and pyrrole derivatives containing the difluoromethylene fragment at the N atom were studied. 1-(1,1,2,2-Tetrafluoroethyl)pyrrole, 1-(1,1,2,2-tetrafluoroethyl)imidazole, and 1-(2-chloro-1,1,2-trifluoroethyl)imidazole were used as substrates. 1-Alkyl-3-(1,1,2,2-tetrafluoroethyl)- and 1-alkyl-3-(2-chloro-1,1,2-trifluoroethyl)imidazolium iodides were obtained. These can be used as intermediates for preparation of new ionic liquids of the imidazole series and 1-alkyl-3-polyfluoroethylimidazole-2-thiones.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 781–787, March, 2005. 相似文献
12.
Frans Compernolle M.-Ashty Saleh Suzanne Toppet Wim De Buysser Georges Hoornaert 《Journal of heterocyclic chemistry》1991,28(8):1965-1969
The synthesis of the tetracyclic title compounds, acetal 5 and ketone 6 , is presented. The key step, formation of the imidazole ring to give compound 5 , involved the acid catalysed dehydration of the 2-(o-aminophenyl)lactam 7b . This was generated from lactam 4 via N-substitution with o-nitrofluorobenzene and reduction of the nitro group. Deprotection of acetal 5 afforded ketone 6 which through a temperature dependence study of vicinal coupling constants was shown to occur as an equilibrium of trans- and cis-fused forms A and B . 相似文献
13.
α‐exomethylene lactone possessing acetal–ester linkage: Polymerization and postpolymerization modification for water‐soluble polymer
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Yasuhiro Kohsaka Yusuke Matsumoto Tianyi Zhang Yosuke Matsuhashi Tatsuki Kitayama 《Journal of polymer science. Part A, Polymer chemistry》2016,54(7):955-961
2,6‐Dimethyl‐5‐methylene‐1,3‐dioxa‐4‐one (DMDO), a cyclic acrylate possessing acetal–ester linkage, was obtained as a mixture of cis‐ and trans‐isomers (95:5) from Baylis–Hillman reaction of an aryl acrylate. The radical and anionic polymerizations of DMDO yielded the corresponding vinyl polymers without any side reactions such as cleavage of the acetal–ester linkage. The polymerization behaviors were significantly different from that of the acyclic acrylate, α‐(hydroxymethyl)acrylic acid, which was expected inactive against polymerization due to the steric hindrance around the vinylidene group by the α‐substituent. The acetal–ester linkage of the obtained polymer ( P1 ) was completely cleaved via acid hydrolysis to afford a water soluble polymer, P2 . © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 955–961 相似文献
14.
The reaction of 1,1,2‐ethenetricarboxylic acid 1,1‐diethyl ester with E‐3‐(2‐furyl)‐2‐propenylamines under the amide condensation conditions (EDCI/HOBt/Et3N) on heating at 80–110°C afforded cis‐fused tricyclic compounds, furo[2,3‐f]isoindoles as major product. On the other hand, the reaction with E‐3‐(3‐furyl)‐2‐propenylamines afforded trans‐fused tricyclic compounds predominantly. The formation of amide/[4 + 2] cycloaddition/hydrogen‐shift reactions proceed sequentially. The observed stereoselectivity of the fused rings has been investigated by the density functional theory calculations. The reaction of 1,1,2‐ethenetricarboxylic acid 1,1‐diethyl ester with 3‐(3‐pyridinyl)‐2‐propen‐1‐amine under the amide condensation conditions afforded HOBt‐incorporated 3,4‐trans‐pyrrolidine selectively. The chemoselectivity and stereoselectivity of the reactions with (3‐heteroaryl)‐2‐propen‐1‐amines depend on the nature of heteroarenes. 相似文献
15.
Yanmei Wang Hisatoyo Morinaga Atsushi Sudo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2010,48(17):3816-3822
A polymer having acetal moiety in the side chain was synthesized by a reaction of 1,3‐diol structure of poly(vinyl alcohol‐co‐N‐vinylpyrrolidone) and octanal. The hydrophobicity of the resulting acetal moiety and the hydrophilicity of the pyrrolidone moiety allowed the polymer to exhibit amphiphilicity. The polymer released octanal by hydrolysis of the acetal side chains under acidic conditions. The release of octanal was enhanced by the increased hydrophilicity of the polymer because of the presence of pyrrolidone moiety. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3816–3822, 2010 相似文献
16.
A. T. Soldatenkov S. A. Soldatova R. R. Suleimanov K. B. Polyanskii V. E. Kotsyuba A. F. Smol’yakov V. N. Khrustalev M. Yu. Antipin 《Russian Journal of Organic Chemistry》2011,47(11):1738-1741
The reaction of N-methyl-N-(diethoxycarbonyl)methyltetrahydropyridinium bromide with dimethyl acetylenedicarboxylate in the presence of triethylamine
at room temperature afforded 1,2-dimethyl 1-ethyl 2-[(3-vinyl-1-methyl-3-phenyl-2-ethoxycarbonyl)pyrrolidin-2-yl]-ethene-1,1,2-tricarboxylate
in 25% yield. Its structure was proved by XRD analysis. At cooling to −20°C the pyrrolidine yield signifi cantly decreased
and 3,4-dimethyl 2,2-diethyl 1-methyl-7-phenyl-1,5,8,9-tetrahydro-2H-azonine-2,2,3,4-tetratcarboxylate was obtained in 31% yield. 相似文献
17.
Koshi Okazaki Shunji Nagase Hajime Baba Kazuo Kodaira 《Journal of fluorine chemistry》1974,4(4):387-397
The electrochemical fluorination of chlorine-containing ethers has been studied. In general, it was found that a chlorine bonded to an a-carbon atom in the ethers was readily removed during electrochemical reaction in anhydrous hydrogen fluoride, whilst a chlorine bonded to the β-carbon atom was retained to yield β-chlorinated polyfluoroethers.Through the use of this method, several new chloropolyfluoroethers, e.g. 2-chloro-1,1,2,2-tetrafluoroethyl difluoromethyl ether, 2,2-dichloro-1,1,2-trifluoroethyl trifluoromethyl ether 2,2-dichloro-1,1,2-trifluoroethyl difluoromethyl ether, 2,2-dichloro-1,1,2-trifluoroethyl chlorodifluoromethyl ether, 2-chloro-1,1,2,2-tetrafluoroethyl chlorodifluoromethyl ether and 2,2-trichloro-1,1-difluoroethyl trifluoromethyl ether, have isolated and characterized. 相似文献
18.
Hisatoyo Morinaga Hiroshi Morikawa Atsushi Sudo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2009,47(13):3241-3247
A methacrylate having a hydrophilic poly(ethylene glycol) chain and 2‐(N,N‐dimethylamino)ethyl methacrylate were radically copolymerized to obtain a statistical hydrophilic copolymer having tertiary amino groups in the side chains. The obtained polymeric amine was quantitatively quaternarized by a benzyl chloride‐type molecule having an acetal moiety derived from geraniol, which is a hydrophobic alcohol widely used as a fragrance ingredient. The resulting copolymer, which had PEG chain and the quaternary ammonium moieties as hydrophiles and the acetal moieties as hydrophobes, exhibited amphiphilicity to form stable associates in water. The acetal moieties were stable for 30 days at pH 9, while they were gradually hydrolyzed at pH 4 to release geraniol continuously at least for 30 days, confirming the potential applicability of the copolymer to a controlled releasing system of functional molecules. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3241–3247, 2009 相似文献
19.
(E)‐ and (Z)‐1,2‐bis(trifluoromethyl)ethene‐1,2‐dicarbonitrile ((E)‐ and (Z)‐BTE, resp., =(E)‐ and (Z)‐2,3‐bis(trifluoromethyl)but‐2‐enedinitrile) were used as a stereochemical probe in studying (2+2) cycloadditions of acceptor with donor alkenes. The additions to methyl (E)‐ and (Z)‐propenyl ether gave rise to the eight conceivable cyclobutanes 8 , although in different ratios in reactions of (E)‐ and (Z)‐BTE. The 19F‐NMR data served the structural assignment and the quantitative analysis. The mechanistic discussion is based on rotations and ring closures of the assumed 1,4‐zwitterionic intermediates. Dimethylketene dimethyl acetal, methylketene dimethyl acetal, and ketene diethyl acetal show an increasing rate in their reactions with BTE as well as in the equilibration of the cycloadducts. 相似文献
20.
Stereoselective synthesis of 5‐[2‐(guanin‐9‐yl)‐ and 5‐[2‐(2‐aminopurin‐9‐yl)ethyl]‐2‐D‐ribo‐(1′,2′,3′,4′‐tetrahydroxybutyl)‐1,3‐dioxane, 2‐5, as potential prodrugs of penciclovir, has been accomplished in six steps from readily available 2,3,4,5‐tetra‐O‐acetyl‐aldehydo‐D‐ribose ( 6 ) and the 1,3‐diol 7 . It has been demonstrated that the use of boron trifluoride diethyl etherate (BF3·Et2O) in dichloromethane along with excess anhydrous copper(II) sulfate was crucial for the efficient formation of cyclic acetal 8 . In addition, the chromatographic separation of cis and trans isomers of the cyclic acetal at the bromide stage 10 was feasible, which was requisite for the successful stereoselective synthesis of the ribosyl derivatives 2–5 . 相似文献