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Showing 1 to 20 of 43 for “"Allene."”.
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Reaction of allene with phenyl azide
… insight into the reaction of aryl azides with allenes.
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Synthetic Equivalents to Acetylene and Allene in the Diels-Alder Reaction
Embargo set by: Seth Robbins for item 67446 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs
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Stereochemistry of the Allene-Forming Cycloelimination of 4-Diazo-3,5-Diethyl-3,5-Dimethyl-1-Pyrazoline
The goal of this investigation was the determination of the stereochemical course of the decomposition of diazopyrazoline 1a to 3,5-dimethyl-3,4-heptadiene (2). To achieve this goal, a stereospecific synthesis of 1a which would permit its optical resolution was devised. Cyclization of …
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Organic reactions catalyzed by copper(I) hydride complexes
… CuH-Catalyzed Allylation of Imines with Terminal Allenes A chemoselective hydrometalation process enables the use of easily accessible allenes as allylmetal nucleophile surrogates in imine allylation reactions. By modulating the nitrogen-protecting group, either highly branched- or …
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Nickel-catalyzed coupling reactions and synthetic studies toward ent-dioxepandehydrothyrsiferol via an epoxide-opening cascade
… Coupling Reactions. Nickel-catalyzed allene--aldehyde coupling and alkene--aldehyde coupling represent two methods of preparing allylic alcohols. Most asymmetric transition metal-catalyzed methods of preparing enantiomerically enriched allylic alcohols rely on chiral ligands. The …
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1,2,3-triazoles as X-factor in gold(I) activation of challenging C-C triple bond transformations
… ether. Through a simple 3,3-rearrangement, allene derivatives, which were usually considered as intermediate in the gold(I) chemistry, were isolated as a major product. The treatment of allene derivatives with triazole gold complex showed no apparent decomposition of allene and confirmed the …
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Some uses of tin compounds in organic synthesis.
… of the reaction of a tin cuprate with allenes is described. The cuprate reacts with 1,1-dimethyl allene followed by aqueous work up to give an allyl stannane, or the intermediate copper species can be quenched with a number of different ele,ctrophiles to give further substituted allyl …
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The oxymercuration of allenes
Addition of mercuric acetate to allene and the five possible methyl-substituted allenes was carried out in methanol. The reaction is quite rapid and even quantitative if an equivalent amount of sodium carbonate is added soon after initial mixing of the reagents. Allene yields exclusively …
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Synthetic studies towards total synthesis of bielschowskysin
… core of bielschowskysin. From malic acid, the allene appended butenolide was prepared in 13 steps and [2+2] cycloaddition was carried out under the UV lamps to form the tricyclic core of bielschowskysin. After making the tricyclic core, retrosynthetic analysis of key intermediate leads to left …
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Preparation of benzoenyne -allenes, enyne -isocyanates and enyne -carbodiimides and their applications in the synthesis of polycyclic aromatic hydrocarbons and heterocycles
… reaction of the chlorinated benzoenyne-allene intermediates occurred preferentially to form 1H-cyclobut[a]indenes. Competition from the intramolecular [2+2] cycloaddition reaction could be avoided with the non-chlorinated benzoenyne-allenes, providing direct access to novel polycyclic …
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Synthesis of derivatives of 4H-cyclopenta[ def]phenanthren-4-one and development of synthetic strategies for the polycyclic aromatic hydrocarbons with carbon frameworks represented on the surface of C60
… initial formation of the chlorinated benzoenyne-allene 58. Two cycles of a C2--C6 biradical cyclization reaction followed by a radical-radical coupling then afforded the formal [4+2] Diels-Alder cycloaddition adduct 60, which in turn underwent tautomerization to give 61. Reduction with …
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I. Generation of dibromocarbene under neutral conditions; II. Generation and reactions of 11-carbena[4.4.1]propella-3,8-diene; III. The oxidation of cyclopropylidenes
… ring opens to the corresponding allene, we generated the "free" carbene by LiOCH[subscript]3 decomposition of N-Nitroso-N- (4.4.1) -propella-3,8-dienyl-11-urea. Analysis of the product mixture did not indicate any allene derived product. In the course of this study we postulated a …
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Free radical reactions of allylic and propargylic derivatives
… to form the alkyl-substituted propene or allene and an eliminated radical which regenerates the tert-butyl radical by displacement from t-BuHgCl. With [beta]-oxy substituents, such as O[subscript]2CR, OP(O)(OEt)[subscript]2, O[subscript]3SAr, the adduct radical can displace the alkyl …
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Synthesis of benzocarbazoles, indoloquinolines and indolonaphthridines from thermolysis of benzoenynyl ketenimines and carbodiimides
… thermal behavior are described. Like enyne-allene and enyne-ketene systems, these enyne-hetereocumulenes undergo cycloaromatization through two competing biradical mechanisms under thermal conditions and therefore could serve as potential DNA cleaving agents. The resultant …
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Mechanistic and synthetic studies of the intramolecular [4+2] cycloaddition of conjugated enynes
… of the enyne to give a highly reactive cyclic allene intermediate which isomerizes to aromatic and dihydroaromatic compounds through proton transfer or hydrogen atom transfer mechanisms. Studies of the intramolecular cycloaddition of conjugated arylacetylenes (arenynes) indicated that these …
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Asymmetric Dihydroxylation and Aziridination of Allenes and Related Chemistry
… investigation of asymmetric dihydroxylation of allenes. The efficiency of kinetic resolution of racemic allenes was also investigated by using the AD reaction on both 1,3-disubstituted and trisubstituted allenes. Steric effects, electronic effects and allene substitution are also discussed. …
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Gold-catalyzed synthesis and functionalization of heteroarenes
… cycloaddition reactions of 2-vinylindoles with allene derivatives is presented. This work has allowed to identify two different reaction pathways, a formal 4+2 cycloaddition and a multicomponent reaction, both leading to different tetrahydrocarbazole derivatives. The reaction outcome can be …
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Intramolecular [4+2] cycloadditions of conjugated ynones and related species ; Studies directed toward the total systhesis of glycinoeclepin A
… in which a highly strained heterocyclic allene intermediate undergoes an unusual rearrangement leading to a 3-furfuryl carbene. A 1,2-C-H insertion then produces the polycyclic furan product. A detailed analysis of the scope and mechanism of this reaction is presented. The synthetic …
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