Ethylene derivatives allenes

BoranelmethyllithiumIacetic acid Synthesis of terminal allenes from ethylene derivs. 

Ethylene derivs. Startg. m. allowed to react 2 hrs. at room temp, with tetra-methylammonium fluoride in acetonitrile a-vinylbenzyl alcohol. Y 80%. F. e., limitations, also formation of allenes, s. T. H. Chan and W. Mychajlowskij, Tetrah. Let. 1974f 3479 f. methods, retention of configuration, cf. K. Utimoto, M. Kitai, and H. Nozaki, Tetrah. Let. 1975, 2825. 

A mixture of 3,6-diphenyl-si/m-tetrazine, diphenylacetylene, and toluene refluxed 3 days 3,4,5,6-tetraphenylpyridazine. Y 86%.—A variety of unsatd. compounds, inch aliphatic and alicyclic olefins, styrenes, acetylenes, butadienes, and allene give the above reaction. 3,6-Bis(polyfluoroalkyl)-sym-tetrazines react with particular ease. F. e., also from ethylene derivatives via 1,4-dihydropyridazines, s. R. A. Garboni and R. V. Lindsey, Jr., Am. Soc. 81, 4342 (1959). 

Allenes from ethylene derivatives Synthesis with insertion of 1 G-atom One-step procedure... 

The irradiation of the thiophene in gas phase yields ethylene, allene, methyl-acetylene, carbon disulfide, and vinylacetylene. No Dewar thiophene or cyclo-propene derivatives were isolated (69CJC2965). The irradiation in liquid phase gave the Dewar thiophene which can be trapped as a Diels-Alder adduct with furan (85JA723). The Dewar thiophene and cyclopropene-3-thiocarbaldehyde can be obtained by irradiation in argon matrices at 10 K (86JA1691). 

Ethylene and styrene derivatives react with various propargylic silyl ethers in the presence of zirconocene(II) to afford allenic products in high yield (Scheme 5.7). For example, substrate 67 was transformed into the trisubstituted allene hydrocarbon 68 in 93% yield under the reaction conditions [20]. In the synthesis of various tetraalkylated allenes, in which several of the alkyl substituents also contained triple bonds, allowing these substrates to be cydized intramolecularly into aromatic com-... 

Allen TM, Hansen C, Martin F, Redemann C, Yau-Young A. Liposomes containing synthetic lipid derivatives of poly(ethylene glycol) show prolonged circulation half-lives in vivo. Biochim Biophys Acta 1991 1066 29. 

Regioselective stannylcupration of terminal alkynes and allenes, followed by quenching of the cuprate intermediate with ethylene oxide, provides a facile synthesis of cyclobutene and alkylidine cyclobutane derivatives, respectively (Scheme 3.23) [15c]. A number of total syntheses have exploited regioselective stannylcup-... 

The first nonintroductory section of the text starts with the observation made early in this century that cyclopropanes have significant olefinic character. That is, corresponding ethylene and cyclopropane derivatives have significant similarities. There are literature comparisons of the thermochemistry of direct counterparts such as the parent species (1 and 2, X = H), propene and methylcyclopropane with X = Me, and of methyl acrylate and methyl cyclopropanecarboxylate 8 with X = COOMe. But the chemistry of substituted eth-ylenes is far richer than just that of vinyl compounds. One can retrieve enthalpy of formation data for cumulenes ( cumulenated olefins) such as allene (3) and both cis- and trans-2,3,4-hexatriene (4a and 4b), and for conjugated olefins such as 1,3-butadiene (5) and both (Z)- and (E)-1,3,5-hexatriene (6a and 6b). For the cyclopropane chemist it is natural to... 

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