Trichalcogenasupersumanenes and its concave-convex supramolecular assembly with fullerenes.

Synthesis of buckybowls have stayed highly challenging due to the large structural strain caused by curved π surface. In this paper, we report the synthesis and properties of two trichalcogenasupersumanenes which three chalcogen (sulfur or selenium) atoms and three methylene groups bridge at the bay regions of hexa-peri-hexabenzocoronene. These trichalcogenasupersumanenes are synthesized quickly in three steps using an Aldol cyclotrimerization, a Scholl oxidative cyclization, and a Stille type reaction. X-ray crystallography analysis reveals that they encompass bowl diameters of 11.06 Å and 11.35 Å and bowl depths of 2.29 Å and 2.16 Å for the trithiasupersumanene and triselenosupersumanene, respectively. Furthermore, trithiasupersumanene derivative with methyl chains can form host-guest complexes with C60 or C70, which are driven by concave-convex π ⋯ π interactions and multiple C-H ⋯ π interactions between bowl and fullerenes.

Rh(III)-Catalyzed [4 + 1] Annulation of Sulfoximines with Maleimides: Access to Benzoisothiazole Spiropyrrolidinediones.

Rh(III)-catalyzed synthesis of benzoisothiazole spiropyrrolidinediones using sulfoximine as a directing group under a C-H activation and [4 + 1] annulation strategy with maleimides as a coupling partner is reported. The cyclization reaction was compatible with various substituted sulfoximine and maleimides. The deuterium-labeling studies were performed to investigate the mechanism of the reaction.

Cp*RhIII-Catalyzed Cascade Annulation of Arylimidates with Pyridotriazoles toward Isoquinolin-3-ol Derivatives.

A Cp*RhIII-catalyzed efficient synthesis of isoquinolin-3-ol derivatives bearing a pyridinyl ring using imidate as a directing group under C-H activation strategy with pyridotriazoles as carbene reagents is reported. In this reaction, cascade C-H activation, regioselective cyclization, and elimination occur in one pot. The present methodology featured a good range of functional group tolerance and furnished the target products in moderate-to-excellent yields.

A contorted nanographene shelter.

Nanographenes have kindled considerable interest in the fields of materials science and supramolecular chemistry as a result of their unique self-assembling and optoelectronic properties. Encapsulating the contorted nanographenes inside artificial receptors, however, remains challenging. Herein, we report the design and synthesis of a trigonal prismatic hexacationic cage, which has a large cavity and adopts a relatively flexible conformation. It serves as a receptor, not only for planar coronene, but also for contorted nanographene derivatives with diameters of approximately 15 Å and thicknesses of 7 Å. A comprehensive investigation of the host-guest interactions in the solid, solution and gaseous states by experimentation and theoretical calculations reveals collectively an induced-fit binding mechanism with high binding affinities between the cage and the nanographenes. Notably, the photostability of the nanographenes is improved significantly by the ultrafast deactivation of their excited states within the cage. Encapsulating the contorted nanographenes inside the cage provides a noncovalent strategy for regulating their photoreactivity.

1,2,5,6,9-Pentaazacoronenes (PACs) and π-Extended PAC Derivatives: Synthesis, Crystal Structure, and Optical and Redox Properties.

A novel class of 1,2,5,6,9-pentaazacoronene (PAC, 1) derivatives and π-extended PAC derivatives, chromeno[2,3,4-ij]pentaazacoronenes (CPACs, 2), has been successfully synthesized on the basis of intramolecular diazo-coupling reaction and Pictet-Spengler cyclization. Single-crystal analysis demonstrates that 1o (R1 = H) displays a herringbone packing motif while 1s (R1 = C3F7) packs into an S-shaped arrangement. Photophysical and electrochemical studies indicated that the new PAC system manifested significantly red-shifted absorption and emission capacity, larger Stokes shifts, and narrower HOMO-LUMO energy gaps.

Palladium-Catalyzed Oxidative Annulation of Sulfoximines and Arynes by C-H Functionalization as an Approach to Dibenzothiazines.

This work reports a novel and efficient palladium-catalyzed synthesis of tricyclic dibenzothiazines using easily prepared aryl sulfoximines and aryne precursors via C-H functionalization and cyclization. A mechanistic investigation indicated that the C-H bond cleavage at the position ortho to the sulfoximine group is the rate-determining step.

A general method for site-selective Csp3-S bond formation via cooperative catalysis.

Herein, we report a copper-catalysed site-selective thiolation of Csp3-H bonds of aliphatic amines. The method features a broad substrate scope and good functional group compatibility. Primary, secondary, and tertiary C-H bonds can be converted into C-S bonds with a high efficiency. The late-stage modification of biologically active compounds by this method was also demonstrated. Furthermore, the one-pot preparation of pyrrolidine or piperidine compounds via a domino process was achieved.

Diverse secondary C(sp3)-H bond functionalization via site-selective trifluoroacetoxylation of aliphatic amines.

We describe a coinage-metal-catalyzed site-selective oxidation of secondary C(sp3)-H bonds for aliphatic amine substrates. Broad amine scope, good functional compatibility and late-stage diversification are demonstrated with this method. The steric demand of the ß-substituents controlled diastereoselectivities under this catalytic system. The site selectivity favors secondary C(sp3)-H bonds over tertiary ones underscoring the unique synthetic potential of this method.

A Polyaromatic Nano-nest for Hosting Fullerenes C60 and C70.

A "Janus" type of hexa- cata-hexabenzocoronene with three triptyceno subunits fused symmetrically on the periphery of coronene has been synthesized using a covalent self-assembly strategy. The triptyceno subunits form a nanosized nest on one side of the aromatic plane with space-matching fullerenes such as C60 and C70 to afford shape-complementary supramolecular complexes. The formation of the complexes in solution was confirmed by 1H NMR and fluorescence titration. Four complexes with C60 or C70 were obtained and studied by single-crystal X-ray diffraction analysis. In the crystal structure, the host shows a proper tunability to adjust its conformation in accordance with the shape of the guest. The different stoichiometric ratios and various stacking patterns of the complexes suggest the diversity of this nonplanar polyaromatic host in complexation with fullerenes.

Copper-catalyzed remote (δ) C(sp3)-H bond amination: a practical strategy to construct pyrrolidine derivatives.

We report a copper-catalyzed remote C(sp3)-H bond amination reaction that converts acyclic amines to pyrrolidines. This reaction occurs selectively at the carbon δ to the amine functionality. Primary, secondary and tertiary C-H bonds are all suitable for the amination reactions in the presence of an inexpensive and commercially available copper catalyst.

Facile Synthesis of π-Extended Viologens: Electron-Deficient Polycyclic Aza-aromatics.

A novel family of π-extended viologens has been synthesized by a concise 3-step route from simple and readily available chemicals. The π-enlargement gives the system new photophysical and electrochemical properties such as photoluminescence and changed redox potentials.

Catalyst-Free Three-Component Tandem CDC Cyclization: Convenient Access to Isoindolinones from Aromatic Acid, Amides, and DMSO by a Pummerer-Type Rearrangement.

A catalyst-free multicomponent CDC reaction is rarely reported, especially for the intermolecular tandem CDC cyclization, which represents an important strategy for constructing cyclic compounds. Herein, a three-component tandem CDC cyclization by a Pummerer-type rearrangement to afford biologically relevant isoindolinones from aromatic acids, amides, and DMSO, is described. This intermolecular tandem reaction undergoes a C(sp(2) )-H/C(sp(3) )-H cross-dehydrogenative coupling, C-N bond formation, and intramolecular amidation. A notable feature of this novel protocol is avoiding a catalyst and additive (apart from oxidant).

A convenient synthesis of N-aryl benzamides by rhodium-catalyzed ortho-amidation and decarboxylation of benzoic acids.

The rhodium-catalyzed amidation of substituted benzoic acids with isocyanates by directed CH functionalization followed by decarboxylation to afford the corresponding N-aryl benzamides is demonstrated, in which the carboxylate serves as a unique, removable directing group. Notably, less common meta-substituted N-aryl benzamides are generated readily from more accessible para- or ortho-substituted groups by employing this strategy.

Facile bottom-up synthesis of coronene-based 3-fold symmetrical and highly substituted nanographenes from simple aromatics.

A facile and efficient self-sorting assemble (CSA) strategy has been paved for bottom-up construction of the 3-fold symmetrical and highly substituted hexa-cata-hexabenzocoronenes (c-HBCs), the trithieno analogues, and larger disc-shaped PAHs from simple chemicals using benzylic carbons as tenon joints and a novel FeCl3-mediated AAA process as a key step. The structures of the as-prepared c-HBCs and related NGs were clearly identified by spectral analyses and X-ray crystallographic studies. Moreover, these can be envisaged to serve as new launching platforms for the construction of larger and more complex π-conjugated molecules and supramolecular architectures because of the modifiable and symmetrical decorations.

A facile and practical copper powder-catalyzed, organic solvent- and ligand-free Ullmann amination of aryl halides.

A facile and practical method that the copper powder-catalyzed Ullmann amination of aryl halides with aqueous methylamine under organic solvent- and ligand-free condition at 100 °C and in air gave N-arylamines as sole products in good to excellent yields. The presence of a small amount of air is essential. Other aliphatic primary amines show good to very high reactivity. Secondary amines and aniline are not reactive. Sensitive substituents (i.e., CHO, MeCO, CN and Cl) are tolerable in the reaction.

A novel class of C3d symmetrical molecules synthesized by a six-fold substitution from 1,4,5,8,9,12-hexabromododecahydrotriphenylene.

The synthesis of a novel class of hexa-arm molecules with C(3d) symmetry via a simultaneous six-fold nucleophilic substitution reaction from 1,4,5,8,9,12-hexabromododecahydrotriphenylene has been described.

K3PO4-catalyzed regiospecific aminobromination of beta-nitrostyrene derivatives with N-bromoacetamide as aminobrominating agent.

A very simple, efficient, and regiospecific protocol for aminobromination of a wide scope of beta-nitrostyrene derivatives with N-bromoacetamide (NBA) as nitrogen/bromine sources has been developed by using K(3)PO(4) as catalyst. The reaction proceeded smoothly and cleanly to give the bromoamines in good to excellent yields (78-99%) within 24 h in CH(2)Cl(2) at room temperature without protection of inert gases. A possible mechanism involving a nucleophilic conjugate addition was proposed.

Silicon powder: the first nonmetal elemental catalyst for aminobromination of olefins with TsNH(2) and NBS.

Silicon powder was found, for the first time, to be an efficient alternative to transition metal catalysts for aminobromination of alpha,beta-unsaturated carbonyl compounds and simple olefins with p-toluenesulfonamide (4-TsNH(2)) and NBS, affording the aminobrominated products in high yields and regio- and stereoselectivity. The high reactivity of electron-rich substrates reveals that the reaction has the electrophilic addition feature.

KI-catalyzed aminobromination of olefins with TsNH(2)-NBS combination.

An efficient KI-catalyzed aminobromination of olefins has been developed with good to excellent yields and high regio- and stereoselectivities under transition metal-free conditions. A series of olefins, including alpha,beta-unsaturated carbonyl compounds and simple olefins, was studied. The reaction was performed in CH(2)Cl(2) using KI as the catalyst and TsNH(2) and NBS as the nitrogen and bromine sources.