- Process for the preparation of beta-chlorovinyl ketones
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β-Chlorovinyl ketones are prepared by reacting acyl chlorides with acetylene in chloroaluminate-containing ionic liquids. The process gives high yields without formation of tarry byproducts.
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Page/Page column 6-7
(2011/11/12)
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- Efficient synthesis of β-chlorovinylketones from acetylene in chloroaluminate ionic liquids
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A method for the Friedel-Crafts-type insertion reaction of acetylene with acid chlorides in chloroaluminate ionic liquids is presented. The use of ionic liquids not only serves to avoid the use of carbon tetrachloride or 1,2-dichloroethane but also suppresses side reactions, notably the polymerization of acetylene, which occurs in these chlorinated solvents. Consequently, the products can be isolated using a simpler purification procedure, giving a range of aromatic and aliphatic β-chlorovinyl ketones in high yield and purity.
- Snelders, Dennis J. M.,Dyson, Paul J.
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supporting information; experimental part
p. 4048 - 4051
(2011/10/04)
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- A novel and simple route for the synthesis of 3,4-disubstituted pyrroles
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A new class of 3,4-disubstituted pyrroles has been prepared by the reaction of 1-aroyl-2-arylsulfonylethenes and 1,2-diarylsulfonylethenes with tosyl methyl isocyanide.
- Padmavathi, Venkatapuram,Reddy, Boggu Jagan Mohan,Padmaja, Adivireddy
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p. 333 - 335
(2007/10/03)
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- Flash vacuum pyrolysis over magnesium. Part 1 - Pyrolysis of benzylic, other aryl/alkyl and aliphatic halides
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Flash vacuum pyrolysis over a bed of freshly sublimed magnesium on glass wool results in efficient coupling of benzyl halides to give the corresponding bibenzyls. Where an ortho halogen substituent is present further dehalogenation gives some dihydroanthracene and anthracene. Efficient coupling is also observed for halomethylnaphthalenes and halodiphenylmethanes while chlorotriphenylmethane gives 4,4′-bis(diphenylmethyl)biphenyl. By using α,α′-dihalo-o-xylenes, benzocyclobutenes are obtained in good yield, while the isomeric α,α′-dihalo-p-xylenes give a range of high thermal stability polymers by polymerisation of the initially formed p-xylylenes. Other haloalkylbenzenes undergo largely dehydrohalogenation where this is possible, in some cases resulting in cyclisation. Deoxygenation is also observed with haloalkyl phenyl ketones to give phenylalkynes as well as other products. With simple alkyl halides there is efficient elimination of HCl or HBr to give alkenes. For aliphatic dihalides this also occurs to give dienes but there is also cyclisation to give cycloalkanes and dehalogenation with hydrogen atom transfer to give alkenes in some cases. For 5-bromopent-1-ene the products are those expected from a radical pathway but for 6-bromohex-1-ene they are clearly not. For 2,2-dichloropropane and 1,1-dichloropropane elimination of HCl occurs but for 1,1-dichlorobutane, -pentane and -hexane partial hydrolysis followed by elimination of HCl gives E, E-, E,Z- and Z,Z- isomers of the dialk-1-enyl ethers and fully assigned 13C NMR data are presented for these. With 6-chlorohex-1-yne and 7-chlorohept-1-yne there is cyclisation to give methylenecycloalkanes and -cycloalkynes. The behaviour of 1,2-dibromocyclohexane and 1,2-dichlorocyclooctane under these conditions is also examined. Various pieces of evidence are presented that suggest that these processes do not involve generation of free gas-phase radicals but rather surface-adsorbed organometallic species.
- Aitken, R. Alan,Hodgson, Philip K.G.,Morrison, John J.,Oyewale, Adebayo O.
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p. 402 - 415
(2007/10/03)
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- A novel route for the synthesis of unsaturated oxo sulfones and bissulfones
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The reaction between vinyl chloride and aroyl/arylsulfonyl chloride under Friedel-Craft's reaction conditions was the basis for the synthesis of unsaturated oxo sulfones and bissulfones.
- Reddy, D. Bhaskar,Babu, N. Chandrasekhar,Padmavathi,Sumathi
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p. 491 - 494
(2007/10/03)
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- A Novel Regio- and Stereospecific Hydrohalogenation Reaction of 2-Propynoic Acid and Its Derivatives
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2-Propynoic acid and its derivatives are hydrohalogenated regio- and stereospecifically by reaction with lithium halides in acetic acid, or preferably with 1 equiv of acetic acid in refluxing CH3CN, to afford the thermodynamically unfavorable (Z)-3-halopropenoic acids and their derivatives as sole products.A rationale for the regio- and stereospecifity is briefly discussed.
- Ma, Shengming,Lu, Xiyan,Li, Zhigang
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p. 709 - 713
(2007/10/02)
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- Cobalt(II)chloride catalysed cleavage of ethers with acyl halides: Scope and mechanism
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Cobalt(II) chloride in acetonitrile catalyses the cleavage of a wide variety of ethers with acyl halides under mild conditions to give the corresponding esters in good yields. Acyclic aliphatic ethers are cleaved to the corresponding ester and chlorides whereas the cyclic aliphatic ethers give rise to the ω-chloroesters. The benzyl ethers can be converted to the corresponding esters along with the formation of benzyl chloride and benzyl acetamide. A comparative study for the cleavage of allyl and benzyl ether has revealed that benzyl ether can be selectively cleaved in presence of the allyl ethers. The oxiranes can be cleaved in highly regioselective manner to the corresponding-β-chloroesters. The vinyl ethers undergo sp2-hybridised carbon-oxygen bond cleavage under these conditions. Based on product analysis, a mechanism involving electron transfer followed by O-acylation and S(N)1 or S(N)2 attack by chloride-ion is discussed.
- Iqbal,Srivastava
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p. 3155 - 3170
(2007/10/02)
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- Methods for the introduction of a Phenylselenium Dichloride Group into he α-position of Carbonyl Compounds. Syntheses of Enones.
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Phenylselenium trichloride, PhSeCl3, direcly introduced, in fair yield, a PhSeCl2 group into the α-position of ketones with loss of HCl.To some extent, depending on the substrate, this reagent was also shown to act as a chlorinating agent toward ketones, yielding α-chloro ketones and α-phenylselenenyl ketones.The latter compounds were readily converted to selenium(IV) dichlorides by SO2Cl2 chlorination to significantly improve the overall yields of the selenetion process.The consecutive treatment of ketones with PhSeCl and SO2Cl2 could also be used for the introduction of a PhSeCl2 group, but this procedure was usually less efficient than the PhSeCl3-based one.Unsymmetrical ketones were selenated with poor regiocontrol.Aldehydes were primarily chlorinated by treatment with PhSeCl3, but consecutive treatment with PhSeCl3 and SO2Cl2 introduced a PhSeCl2 group into the α-position.Carboxylic acids and esters were ureactive toward PhSeCl3 and PhSeCl.PhSeCl3 underwent addition reactions with enones to introduce a PhSeCl2 group α or β to the carbonyl group, depending on the substrate.The carbonyl compounds substituted in the α-position with a PhSeCl2 group were easily converted to the corresponding α,β-unsaturated carbonyl compounds after hydrolysis/selenoxide elimination.Since the selenium(IV) intermediates involved were highly crustalline and easy to purify, the preparation of enones from symmetrical ketones via PhSeCl2 introduction/hydrolytic elimination was especially convenient to perform from the operational point of view.
- Engman Lars
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p. 4031 - 4037
(2007/10/02)
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- 7-Oxabicycloheptane substituted enaminone prostaglandin analogs and their use in treatment of thrombolytic disease
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7-Oxabicycloheptane substituted enaminone prostaglandin analogs are provided having the structural formula STR1 and including all stereoisomers thereof. The compounds are cardiovascular agents useful, for example, in the treatment of thrombolytic disease.
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- STEREOSELECTIVE SYNTHESIS AND THERMAL BEHAVIOR OF (Z)-EPOXYHEXENYNES: A SIMPLE AND GENERAL ROUTE TO 2-VINYLFURANS
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An efficient approach for the synthesis of 2,3-disubstituted furans (2a-j/3a-j) is described by using the thermally induced rearrangement of epoxyhexenynes (1a-j) which are prepared by streoselective synthesis of the (Z)-pentenynals 10 and subsequent Darz
- Eberbach, Wolfgang,Roser, Joachim
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p. 2797 - 2802
(2007/10/02)
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