Inclusion of Anionic Guests inside a Molecular Cage with Palladium(II) Centers as Electrostatic Anchors
作者:Guido H. Clever、Shohei Tashiro、Mitsuhiko Shionoya
DOI:10.1002/anie.200902717
日期:2009.9.7
Anchors away! Four banana‐shaped ligands and two PdII ions assemble quantitatively to form a ball‐shaped object with four large portals (see picture). The two PdII ions form stable, square‐planar complexes with the pyridyl donors of the ligands, but can undergo further interactions with anions. Their positioning in a confined distance by the rigid ligands make them act as electrostaticanchors for
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.
Allenyl chloromethyl sulfones, new dienophile-diene synthons. A simple iterative ring-growing procedure