Molecular ladders constituted of laterally-fused 1,4-cyclohexadiene subunits. Open-chain models of the [n]beltenes.
摘要:
A practical synthesis of 2,3,6,7-tetramethylene-1,4,5,8-tetrahydronaphthalene (11) has opened up several avenues for the elaboration of molecules consisting largely or exclusively of 1,2:4,5-fused 1,4-cyclohexadiene subunits. Diels-Alder addition of dienophiles to both 1,3-diene segments of this reactive hydrocarbon leads directly to 1,4,5,6,7,10,11,12-octahydrotetracene and substituted derivatives of this polyolefin. A route to the hexacene homolog is available by twofold [4 + 2] cycloaddition of a benzyne followed by Birch reduction. For reasons of solubility, the benzyne should carry alkyl groups in its 4- and 5-positions. Finally, a two-step cyclohomologation scheme is described that allows for the systematic controlled extension of the structural features present in 11 to its tetra- and hexacyclic congeners. The insolubility of the latter hydrocarbon limits its further exploitation in synthesis.
Die palladiumkatalysierte Cocyclisierung von Allenen mit elektronenarmen Alkinen. Einige Untersuchungen zur Kupplung von Allenderivaten mit Acetylendicarbonsäuredimethylester an Palladium und Platin
作者:Constantin Stephan、Christina Munz、Heindirk tom Dieck
DOI:10.1016/0022-328x(94)80060-x
日期:1994.4
ethers even enable a one-pot synthesis (with lower yields) via catalyst-induced elimination of alcohol from an initially formed bis(alkoxy)-tetrahydronaphthalene. 4-Methylidene-palladacyclopent-2-enes can be trapped in stoichiometric reactions with allene derivatives (but not allene itself) and dimethyl acetylenedicarboxylate. Coupling of two allene moieties on platinum affords bis(methylidene)-metallacyclopentanes
Molecular ladders constituted of laterally-fused 1,4-cyclohexadiene subunits. Open-chain models of the [n]beltenes.
作者:Ron J. Graham、Leo A. Paquette
DOI:10.1021/jo00123a009
日期:1995.9
A practical synthesis of 2,3,6,7-tetramethylene-1,4,5,8-tetrahydronaphthalene (11) has opened up several avenues for the elaboration of molecules consisting largely or exclusively of 1,2:4,5-fused 1,4-cyclohexadiene subunits. Diels-Alder addition of dienophiles to both 1,3-diene segments of this reactive hydrocarbon leads directly to 1,4,5,6,7,10,11,12-octahydrotetracene and substituted derivatives of this polyolefin. A route to the hexacene homolog is available by twofold [4 + 2] cycloaddition of a benzyne followed by Birch reduction. For reasons of solubility, the benzyne should carry alkyl groups in its 4- and 5-positions. Finally, a two-step cyclohomologation scheme is described that allows for the systematic controlled extension of the structural features present in 11 to its tetra- and hexacyclic congeners. The insolubility of the latter hydrocarbon limits its further exploitation in synthesis.