Diels-Alder cycloadditions of functionalized (Z)-1-benzylidene-2-methylene cyclohexanes: the beneficial effect of high pressure

Diels-Alder cycloaddition reactions have been studied on substituted (Z)-1-benzylidene-2-methylene cyclohexanes 3. The use of very reactive dienophiles allowed the formation of the expected polycyclic structures whereas hyperbaric conditions (16 kbar) were necessary to form the adducts with less reactive dienophiles. An exo stereoselectivity was observed during the reaction with acrylates.     

Intramolecular double or triple Suzuki coupling reaction of substituted di- or tribromobenzenes. An easy synthesis of fused tri- or tetracycles with a benzene core

Double or triple intramolecular Suzuki coupling reaction has been developed for the efficient synthesis of tri- or tetracyclic products with a benzene core in good yields. The reaction was realized via a one-pot procedure combining the hydroboration of the CC bond in the starting aryl halides and the intramolecular Suzuki coupling.     

Cyclic Hydroboration – The Structure of Perhydro‐9b‐boraphenalenes

Complete hydroboration of cyclododecatrienes was reported to give two isomers, depending on conditions. The assignment of their structure had been attempted without unequivocal proofs. We have now used NMR spectroscopy (¹¹B, ¹³C, ¹⁵N and ²³Na NMR) to study the sodium amides of these two polycyclic boranes. In addition, one of the isomeric borates could be crystallized, and the X‐ray analysis revealed a cis‐,cis‐,trans configuration of the six‐membered rings reversing the original structural assignment.     

Diazadiboraacenes: Synthesis,Spectroscopy and Computations

The incorporation of heteroatoms into hydrocarbon compounds greatly expands the chemical space of molecular materials. In this context, B−N doping takes a center stage due to its isosterism with a C=C-bond. Herein, we present a new and modular synthetic concept to access novel diazadiborabenzo[b]triphenylenes 7 a–h using the B−N doped biradical 16 as intermediate. Characterization of the photophysical properties revealed the emission spectra of the diazadibora benzo[b]triphenylenes 7 a–h can conveniently be tuned by small changes of the substitution on the boron-atom. All of the diazadibora compounds show a short life-time phosphorescence. Additionally, we were able to rationalize the excited-state relaxation of the diazadiboraacene 7 a via intersystem crossing by quantum chemical calculations. The new synthetic strategy provides an elegant route to various novel B−N doped acenes with great potential for applications in molecular materials.     

Stereospecific Sulfur-Mediated Cleavage of a Spirocyclobutanone: Synthesis of a Fully Functional Precursor to the CP Compounds

A reaction sequence made up of a Sakurai reaction, ketene cyclization, sulfur-directed Baeyer–Villiger reaction, and tandem lactone cleavage/isomerization provided the fully functionalized core of the CP compounds. Key steps were the methanolysis of 1 , which leads via 2 to the CP precursor 3 .     

The Li+-Initiated Twofold Dehydrogenation and C−C Bond Formation of Hexaphenylbenzene to the Dilithium Salt of the 9,10-Diphenyltetrabenz[a,c,h,j]anthracene Dianion

Partly solvent-separated and partly solvent-shared , the contact ion triple of the 9,10-diphenyltetrabenz[a,c,h,j]anthracene dianion is formed by the ultrasonically activated reaction of hexaphenylbenzene with lithium metal powder in 1,2-dimethoxyethane (dme) [Eq. (1)]. The proposed microscopic pathway for this reaction—twofold dehydrogenation and C−C bond formation—is supported by quantum-chemical calculations.     

Ultraviolet irradiation of terarylenes: A facile,efficient, and environmentally friendly method for the synthesis of fused polycyclic products

Ultraviolet irradiation of hydroxyl substituted terarylenes provided a simple, efficient, and environmentally friendly method for the synthesis of imidazo[1,2-a]pyridines. The starting terarylenes were prepared via the one-pot, three-component condensation of readily accessible arylglyoxals, 2-aminopyridines, and dimedone.     

A Soluble C60 Graphite Segment

At the limits of analytical investigation one finds the nanodimensional C₆₀ graphite segment 1 , which, thanks to its long-chain alkyl substituents, is soluble. Monolayers of 1 on graphite can be characterized by scanning tunneling microscopy.     

Liquid Crystalline Coronene Derivatives with Extraordinary Fluorescence Properties

Tempering of polystyrene films containing the novel liquid crystalline coronenebis(dicarboximide)s 2 , which are formed by an easy route from perylene-3,4;9,10-tetracarboxylic dianhydride ( 1 ), leads to a shift of the emission within a few seconds. This could be used for dot-by-dot coloring and thus optical displays. The photoluminescence properties of 2 in the solid matrix are dependent on the nature of the aggregates formed.