Hideto Ito

Abstract The annulative π‐extension (APEX) reaction has the potential to have a tremendous impact on the fields of materials science and bioimaging, as well as on the pharmaceutical/agrochemical industries, since it allows access to fused aromatic systems from relatively simple aromatic compounds in a single step. Typically, an APEX reaction facilitates a one‐pot π‐extension without the need to prefunctionalize the aromatic compounds. This advantageous feature is extremely useful for tuning and

Annulative π-extension (APEX) has emerged as a powerful and efficient synthetic method for the construction of polycyclic aromatic hydrocarbons, nanographenes, and π-extended fused heteroarenes. In contrast to classical multistep syntheses requiring substrate prefunctionalization, APEX reactions minimize the number of preparative steps by direct C-H activation of small aromatic templates. In this Perspective, we review recently reported APEX reactions to shed light on the utility, scope, and pro

Molecular nanocarbons containing heptagonal rings have attracted increasing interest due to their dynamic behavior, electronic properties, aromaticity, and solid-state packing. Heptagon incorporation can not only induce negative curvature within nanocarbon scaffolds, but also confer significantly altered properties through interaction with adjacent non-hexagonal rings. Despite the disclosure of several beautiful examples in recent years, synthetic strategies toward heptagon-embedded molecular na

Sulfur-Containing Carbon Nanorings whose phenylene and thienylene units are alternately connected within the ring structure, such as in cyclo-1,4-phenylene-2′,5′-thienylene (CPT), show remarkable photophysical and crystallographic properties, as described by K. Itami et al. in their Communication on page 159 ff. The illustrated picture (provided by Haruko Hirukawa) represents a [4]CPT molecule, which forms a truncated cone shape and interesting tubular stacking in the solid state, similar to oni

New forms of molecular nanocarbon particularly looped polyarenes adopting various topologies contribute to the fundamental science and practical applications. Here we report the synthesis of an infinity-shaped polyarene, infinitene (<b>1</b>) (cyclo[<i>c.c.c.c.c.c.e.e.e.e.e.e</i>]dodecakisbenzene), comprising consecutively fused 12-benzene rings forming an enclosed loop with a strain energy of 60.2 kcal·mol^-1. Infinitene (<b>1</b>) represents a topoisomer of still-hypothetical [12]cir

Graphene nanoribbons are the class of next-generation carbon materials that are attracting many researchers in various research fields. Their unique properties, such as band gap, conductivity, carrier mobility, thermal conductivity, spin polarization, and on-off behavior, heavily depend on structural factors such as edge structure, width, and length. Therefore, the synthesis of graphene nanoribbons with control over these structural factors with atomic precision is crucially important. Among var

The synthesis of cyclo-1,4-phenylene-2',5'-thienylenes (CPTs) as the first example of a thiophene-based, radially π-conjugated system is described. X-ray crystal structures, UV-vis absorption and emission spectra, and theoretical studies revealed the unique structural and photophysical properties of CPTs. With all of these unique structural and photophysical properties, the radially π-conjugated CPTs are expected to open a door for the discovery and development of new functional organic material

Nitrogen-containing polycyclic aromatic compounds (N-PACs) are an important class of compounds in materials science. Reported here is a new aza-annulative π-extension (aza-APEX) reaction that allows rapid access to a range of N-PACs in 11-84 % yields from readily available unfunctionalized aromatics and imidoyl chlorides. In the presence of silver hexafluorophosphate, arenes and imidoyl chlorides couple in a regioselective fashion. The follow-up oxidative treatment with p-chloranil affords struc

Reliable and short synthetic routes to polycyclic aromatic hydrocarbons and nanographenes are important in materials science. Herein, we report an efficient one-step annulative π-extension reaction of alkynes that provides access to diarylphenanthrenes and related nanographene precursors. In the presence of a cationic palladium/o-chloranil catalyst system and dibenzosiloles or dibenzogermoles as π-extending agents, a variety of diarylacetylenes are transformed successfully into 9,10-diarylphenan

A palladium-catalyzed one-step annulative π-extension (APEX) reaction of indoles and pyrroles that allows rapid access to nitrogen-containing polycyclic aromatic compounds is described. In the presence of palladium pivalate and silver carbonate, diverse indoles or pyrroles coupled with diiodobiaryls in a double direct C-H arylation manner to be transformed into the corresponding π-extended compounds in a single step. The newly developed catalytic system enables the use of various pyrroles and in

Abstract Die anellierende Erweiterung von π‐Systemen (APEX‐Reaktion) hat das Potential, die Materialwissenschaften, das Bioimaging und die pharmazeutische/agrochemische Industrie enorm zu beeinflussen, da sie einen Zugang zu kondensierten aromatischen Systemen ausgehend von relativ simplen aromatischen Verbindungen in einem einzigen Schritt ermöglicht. Üblicherweise vereinfacht eine APEX‐Reaktion die Erweiterung eines π‐Systems im Eintopfverfahren, ohne präfunktionalisierte aromatische Verbindun

A cationic gold(I) complex with a semihollow-shaped trialkynylphosphine catalyzed 5-exo-dig and 6-endo-dig cyclizations of various internal alkynic beta-keto esters, showing a marked advantage over a gold(I)-PPh3 complex with respect to the rates of the reactions and the product yields. It is proposed that the gold-bound alkynic substrate in a catalytic pocket must be somewhat folded and that such a steric effect makes the carbon-carbon bond formation entropically more favorable.

A cationic gold(I) complex bearing a semihollow-shaped triethynylphosphine ligand efficiently catalyzed the 7-exo-dig cyclization of silyl enol ethers with an ω-alkynic substituent. The reaction gave various methylenecycloheptane derivatives with an exo- or endocyclic carbonyl group. The protocol was applicable not only to cyclic substrates that form bicyclic frameworks but also to acyclic ones with or without substituents in a carbon chain tether.

Expanded carbohelicenes with structures fused to 15- and 17-benzene were successfully synthesized. Establishing a new synthetic strategy is crucial to realize the development of longer expanded [2,1][<i>n</i>]helicenes with a kekulene-like projection drawing structure. This article describes the sequential integration of the π-elongating Wittig reaction of functionalized phenanthrene units and ring-fusing Yamamoto coupling for the synthesis of [2,1][15]helicenes and [2,1][17]helicenes. X-ray cry

Abstract Molecular nanocarbons containing heptagonal rings have attracted increasing interest due to their dynamic behavior, electronic properties, aromaticity, and solid‐state packing. Heptagon incorporation can not only induce negative curvature within nanocarbon scaffolds, but also confer significantly altered properties through interaction with adjacent non‐hexagonal rings. Despite the disclosure of several beautiful examples in recent years, synthetic strategies toward heptagon‐embedded mol