Synthesis,Structure, Photophysical Properties,and Photostability of Benzodipyrenes

This work explores the syntheses, structures, photophysical properties, and photostability of benzodipyrenes (BDPs). BDPs were synthesized through an InCl₃-AgNTf₂-catalyzed, four-fold alkyne benzannulation reaction. The structures of BDP 4 a and its corresponding endoperoxide product were unambiguously confirmed by X-ray crystallography. The BDPs reported here can also be recognized as peri- and cata-benzannulated pentacenes with a non-functionalized central ring. Unlike the previous reported pentacene-based polycyclic aromatic hydrocarbons, the absorbances of the BDPs were blueshifted by ca. 40 nm relative to pentacene, even after extension of π-conjugation. The newly synthesized BDP products exhibit relatively good stability with half-lives as high as 4612 min in THF.     

Dibenzo[a,f]perylene Bisimide: Effects of Introducing Two Fused Rings

Perylene bisimides (PBIs) are fascinating dyes with various potential applications. To study the effects of introducing a dibenzo‐fused structure to the perylene moiety, π‐extended PBI derivatives with a dibenzo‐fused structure at both of the a and f bonds were synthesized. The twisted structure was characterized by X‐ray crystal structure analysis. In the cyclic voltammograms, the dibenzo[a,f]‐fused PBI showed a reversible oxidation wave at much less positive potential, relative to a dibenzo[a,o]‐fused PBI derivative. These data indicated that two ring fusions at both sides of a naphthalene moiety, which construct a tetracene core, effectively raise the HOMO level compared to fusion of one ring at each naphthalene moiety (two anthracene cores). The dibenzo[a,f]‐fused PBI derivative showed an absorption band at 735 nm with a shoulder band reaching 900 nm.     

Regioselective Synthesis of Polyheterohalogenated Naphthalenes via the Benzannulation of Haloalkynes

Independent control of halide substitution at six of the seven naphthalene positions of 2‐arylnaphthalenes is achieved through the regioselective benzannulation of chloro‐, bromo‐, and iodoalkynes. The modularity of this approach is demonstrated through the preparation of 44 polyheterohalogenated naphthalene products, most of which are difficult to access through known naphthalene syntheses. The outstanding regioselectivity of the reaction is both predictable and proven unambiguously by single‐crystal X‐ray diffraction for many examples. This synthetic method enables the rapid preparation of complex aromatic systems poised for further derivatization using established cross‐coupling methods. The power and versatility of this approach makes substituted naphthalenes highly attractive building blocks for new organic materials and diversity‐oriented synthesis.     

Total Syntheses of Xiamycins A,C, F,H and Oridamycin A and Preliminary Evaluation of their Anti‐Fungal Properties

Divergent and enantiospecific total syntheses of the indolosesquiterpenoids xiamycins A, C, F, H and oridamycin A have been accomplished. The syntheses, which commence from (R)‐carvone, employ a key photoinduced benzannulation sequence to forge the carbazole moiety characteristic of these natural products. Late‐stage diversification from a common intermediate enabled the first syntheses of xiamycins C and F, and an unexpected one‐pot oxidative decarboxylation, which may prove general, led to xiamycin H. All synthetic intermediates and the natural products were tested for anti‐fungal activity. Xiamycin H emerged as an inhibitor of three agriculturally relevant fungal pathogens.     

One‐Pot Synthesis of Polysubstituted Benzenes through a N,N‐dimethyl‐4‐aminopyridine (DMAP)‐Catalyzed [4+2] Benzannulation of 1,3‐Bis(sulfonyl)butadienes and γ‐Substituted Allenoates

A new strategy for the one‐pot synthesis of polysubstituted benzenes through a N,N‐dimethyl‐4‐aminopyridine (DMAP)‐catalyzed [4+2] benzannulation from readily prepared 1,3‐bis(sulfonyl)butadienes and γ‐substituted allenoates is described. This method provides a facile, metal‐free and general route to highly substituted benzenes under mild conditions in moderate‐to‐good yields with complete regioselectivity.     

Rhodium‐Catalyzed Oxidative Benzannulation of N‐Pivaloylanilines with Internal Alkynes through Dual C−H Bond Activation: Synthesis of Highly Substituted Naphthalenes

An efficient method was developed for the synthesis of highly substituted naphthalenes through rhodium‐catalyzed oxidative benzannulation of N‐pivaloylanilines with internal alkynes. The benzannulation reaction proceeded smoothly through dual C?H bond activation to produce the corresponding highly substituted naphthalene products in satisfactory to good yields.     

Toward Möbius and Tubular Cyclopolyarene Nanorings via Arylbutadiyne Macrocycles

By harnessing a highly efficient metal‐catalyzed tandem cycloaddition reaction as the key benzannulation step, a series of cyclopolyarene nanorings of varied sizes are obtained from poly(arylene‐butadiynylene) macrocyclic precursors, which can be synthesized relatively conveniently. Interestingly, due to the nonparallel bond connectivity of the repeat unit, unique Möbius topology is manifested by the cyclopolyarene nanorings composed of an odd number of repeat units, whereas cylindrical tubular structures with radial conjugation are formed with those consisting of an even number of repeat units.     

Novel core-expanded rylenebis(dicarboximide) dyes bearing pentacene units: facile synthesis and photophysical properties

Two synthetic routes for the benzannulation in the "bay"-region of rylenebis(dicarboximide)s leading to new pi-system-expanded chromophores are described. The first route follows a two-step approach: Suzuki coupling of bromo-substituted perylenebis(dicarboximide) with 2-bromophenylboronic acid, followed by palladium-catalysed dehydrobromination. The second route is best described as a palladium-assisted cycloaddition of benzyne, formed in situ, to the bay-region of the bromo-substituted rylene core. Two new types of core-expanded rylene dyes were synthesised: yellow dibenzocoronenebis(dicarboximide)s, absorbing at 490 nm, and a green dinaphthoquaterrylenebis(dicarboximide), which absorbs at 700 nm. These new chromophores are characterised by significant hypsochromic shifts of absorption, compared to their parent rylenebis(dicarboximide)s, excellent photostabilities and high fluorescence quantum yields.