- REACTIONS OF -CYCLOADDITION WITH THE PARTICIPATION OF CYCLOPROPENES AND DICOBALT HEXACARBONYL COMPLEXES OF ACETYLENES
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The reaction of dicobalt hexacarbonyl complexes of acetylene and its phenyl and dimethyl derivatives with the methyl ester of 1-methyl-2-(trimethylsilyl)-1-cyclopropene-3-carboxylic acid with adsorption on a silica gel or NaX zeolite surface leads to the formation of a mixture of bicyclohex-2-en-4-one and tricyclo2,4>heptan-5-one derivatives, whereby the yields and the composition of products are dependent on the type of the adsorbent.It has been found that under the reaction conditions partial isomerization of the bicyclohex-2-en-4-one derivativ es into substituted phenols occurs.Action of anhydrous KF and crown-ether in acetonitrile on the bicyclohex-2-en-4-one derivatives in acetonitrile leads to protodesilylation.
- Kireev, S.L.,Smit, V.A.,Ugrak, B.I.,Nefedov, O.M.
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p. 2240 - 2246
(2007/10/02)
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- Metallacycloalkanes, V. Preparation of a Rhodacycloheptane by Oxidative Coupling of 3,3-Dimethylcyclopropene to Rhodium(I) Complexes
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The rhodacycloheptane derivative 2 is easily prepared in good yields from tris(triphenylphosphane)rhodium chloride or carbonylbis(triphenylphosphane)rhodium chloride and 3,3-dimethylcyclopropene.Spectroscopic data and X-ray analysis show that 2 is monomeric and has a syn,anti,syn structure.The hydrocarbon group of 2 is eliminated by reaction of 2 with CO to give hexamethyl-tris-?-homobenzene (5) and hexamethyl-tris-?-homotropone (4) in a ratio of 1:4.The X-ray structure of 4 is also given.
- Cetinkaya, Bekir,Binger, Paul,Krueger, Carl
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p. 3414 - 3421
(2007/10/02)
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- Reactions of Cyclopropenes, IV. Cyclooligomerisation of 3,3-Dimethylcyclopropene with Palladium(0) Catalysts
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The cyclooligomerisation of 3,3-dimethylcyclopropene (1) with phosphane-free palladium(0) catalysts, e.g. bis(1,5-cyclooctadiene)palladium, bis(dibenzylideneacetone)palladium, or a catalyst prepared "in situ" from palladium acetylacetonate and ethoxydiethylaluminium, leads to the trans-tricyclohexane derivative 2 and to three isomeric tetrakishomocyclooctatetraene compounds (4) .In contrast, a (tri-sec-alkylphosphane)palladium(0) catalyst (Pd/P = 1:1) cyclotrimerises 1 in aromatic hydrocarbons to give the trans-?-trishomobenzene derivative 3 in over 90percent yield.The cyclooligomerisation of 1 using other triorgano-phosphane or -phosphite/palladium(0) catalysts leads to a mixture of products.Besides 2, 3, and 4 a second cyclotrimer of 1 (5) and higher oligomers of 1 are produced.The cyclotrimerisation of 1 to 3 is also influenced by the Pd/phosphane ratio and the solvent used.
- Binger, Paul,McMeeking, John,Schuchardt, Ulf
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p. 2372 - 2382
(2007/10/02)
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