Laticyclic conjugated double bonds within the framework of oligocondensed bicyclo[2.2.2]octenes

Abstract

The all-syn oligocondensed bicyclo[2.2.2]octenes 3, 5, 20 and 29 with two to five etheno bridges show interaction of their -orbitals by -overlap. This laticyclic conjugation reveals itself in the PE and UV spectra of the series as well as in the site selectivity of the Diels-Alder reaction with inverse electron demand found for the dehydro derivatives 11 and 26. As shown in the crystal structures of 3, 5 and 20, the etheno bridges are positioned face to face at a distance which is smaller than the sum of their van der Waals radii.

Aqueous Ti(IV)-Catalyzed Diels-Alder Reaction

“…Without the catalyst, the consistency of the precipitate is markedly less dense and the solution remains golden yellow throughout the reaction with fading color intensity. After 20 hours, the reaction mixtures were filtered and dried in vacuo overnight at ambient temperature to afford exclusively the product, endo-tricyclo-[6.2.2.0 2,7 ]dodeca-4,9-3,6-dione, as confirmed by 1 H-NMR [9].…”

“…The homogeneous reaction mixture was stirred for 20 hours producing an insoluble product which was collected by filtration, dried in vacuo, and weighed (0.778 g, 83% conversion). Comparison of the 1 H-NMR to the published spectra confirmed identification of the product [9]. The procedure was perfomed in triplicate.…”

Reversal of Orbital Symmetry Control in Electrocyclic Ring Closures through Craig‐Möbius Aromaticity

“…This is in accord with the experience that unlike to Heilbronner‐Möbius systems (with Möbius orbital array and Möbius topology), aromatic Zimmerman‐Möbius molecules (with Möbius orbital array but without Möbius topology) were never observed. The C..C distance between CH 2 carbons is rather short in 3 (3.06 Å) compared to the sum of carbon van der Waals radii (3.40 Å), which might imply a feeble interaction by σ‐overlap of π‐orbitals . Next we replaced a CH unit in all polyene reactants 1–3 by an “isolobal” transition metal ([M]) fragment (Figure ).…”

DFT study on the electrophilic transannular addition reaction of bromine to tetracyclo[7.2.1.04,11.06,10]dodeca-2,7-diene

“…Rigid polycyclic molecules having two isolated double bonds located in the laticyclic topology [1] and spatially in close proximity have provided suitable frameworks for the study of transannular interactions and reactions [2][3][4][5]. Attack of an electrophile to a molecule having two isolated double bonds in spatial proximity usually leads to the transannular bridge formation in either cross (Ntype) or parallel (U-type) manner or both [6][7][8][9].…”