Multiple Vinylation of Tribenzotriquinacenes and Fenestrindanes at Their Aromatic Peripheries by Use of Nájera’s Catalyst

From Fragmentation to Construction--from Void to Massive: Fascination with Organic Mass Spectrometry and the Synthesis of Novel Three-Dimensional Polycyclic Aromatic Hydrocarbons

Detailed insights gained from our research into the gas-phase chemistry of ionized and protonated diphenylalkanes and their congeners, obtained by extended synthesis of isotopically labeled model compounds and mass spectrometry, are presented and merged with those acquired during our development of a new family of polycyclic hydrocarbons, the centropolyindanes. Aside from a Personal Account that describes "two scientific lives in one", it is demonstrated, on the one hand, how our understanding of organic chemistry can help to shed light on the details of mass spectrometric fragmentation and to unravel, in a more fundamental way, the unimolecular reactivity of gaseous ions. On the other hand, it is shown how unexpected reactivity of related ions in solution, being subject to the very same fundamentals of organic chemistry, can lead to the construction of novel and, in part, unique three-dimensional polycyclic structures that may contribute to future research in material science. Two such apparently independent fields of organic chemistry may be seen as joint contributions of the art of science.

Oxime-derived palladacycles as source of palladium nanoparticles

Oxime-derived palladacycles are very efficient and versatile pre-catalysts for a wide range of carbon-carbon bond coupling reactions in air, under very low loading conditions, and employing reagent-grade chemicals. This tutorial review presents the main achievements, advantages and limitations of oxime palladacycles as a source of highly active palladium nanoparticles for high-turnover catalyzed Heck, as well as other homo- and cross-coupling reactions usually carried out employing organic or aqueous solvents. Comparison with other ligandless Pd(II) catalysts is also presented. Recent advances to develop supported oxime-derived palladacycles in order to facilitate precatalyst recovery and reuse in cross-coupling reactions, especially under aqueous reaction conditions, are also discussed.

C3v-Symmetrical Tribenzotriquinacenes Extended by Six C1-Functional Groups and the First Triquinacene-Based Tris(dithiametacyclophanes)

The first examples of novel bowl-shaped tribenzotriquinacenes (TBTQs) bearing three dithiametacyclophane units within their arene peripheries are reported. The synthesis is based on a C3v-symmetrical hexakis(chloromethyl)tribenzotriquinacene as the key intermediate and yields the inter-ring metacyclophane-type macrocyclization instead of the intra-ring orthocyclophane-type cyclocondensation. Multiple nucleophilic substitution of the same key intermediate leads to a number of other new 6-fold functionalized tribenzotriquinacenes, some of which may be of interest as readily accessible building blocks for the construction of novel bowl-shaped organic networks. The molecular structures of the novel tris(dithiametacyclophanes) and of the hexakis(chloromethyl)- and hexakis(hydroxymethyl)tribenzo-triquinacenes have been determined by X-ray analysis and interesting host/guest aggregation and torsional effects in the solid state are discussed.

Oxime palladacycles revisited: stone-stable complexes nonetheless very active catalysts

Our review critically presents the main achievements, advantages, and limitations of oxime palladacycles as high-turnover catalysts for Heck, as well as homo- and cross-coupling reactions such as Suzuki-Miyaura, Stille, Ullmann-type, Cassar-Heck-Sonogashira, sila-Sonogashira, Glaser-type, Hiyama, and alkoxycarbonylation reactions. New developments in this area are reviewed from a mechanistic and synthetic point of view. The role of oxime palladacycles as a source of highly active zero-valent palladium species is also discussed.

Functionalized aromatics aligned with the three Cartesian axes: Extension of centropolyindane chemistry

The unique geometrical features and structural potential of the centropolyindanes, a complete family of novel, 3D polycyclic aromatic hydrocarbons, are discussed with respect to the inherent orthogonality of their arene units. Thus, the largest member of the family, centrohexaindane, a topologically nonplanar hydrocarbon, is presented as a "Cartesian hexabenzene", because each of its six benzene units is stretched into one of the six directions of the Cartesian space. This feature is discussed on the basis of the X-ray crystal structures of centrohexaindane and two lower members of the centropolyindane family, viz. the parent tribenzotriquinacenes. Recent progress in multiple functionalization and extension of the indane wings of selected centropolyindanes is reported, including several highly efficient six- and eight-fold C-C cross-coupling reactions. Some particular centropolyindane derivatives are presented, such as the first twelve-fold functionalized centrohexaindane and a tribenzotriquinacene bearing three mutually orthogonal phenanthroline groupings at its molecular periphery. Challenges to further extend the arene peripheries of the tribenzotriquinacenes and fenestrindanes to give, eventually, graphite cuttings bearing a central bowl- or saddle-shaped center are outlined, as is the hypothetical generation of a "giant" nanocube consisting of eight covalently bound tribenzotriquinacene units. Along these lines, our recent discovery of a related, solid-state supramolecular cube, containing eight molecules of a particular tribromotrinitrotribenzotriquinacene of the same absolute configuration, is presented for the first time.