Latest ArticlesDifunctionalization of alkenes have developed into an important type of reactions for rapidly and efficiently assemble complex molecules. While extensive advancements have been achieved by the assistance of transition metal catalysis, the employment of cheap, abundant aryl chlorides as coupling partner is still a challenging task in this field. Herein, we report our first achievement in 1,1-difunctionalization of alkenes with aryl chlorides as coupling partners. The success is predominantly ascribed to the judicious selection of 1,2-diamine ligand. This study provides an efficient protocol for the synthesis of secondary benzyl boronates from easily accessible feedstock chemicals. Furthermore, the distinguished features of this method include excellent 1,1-regio- and chemoselectivity, good functional group tolerance and easily-operational catalytic reaction conditions.
Herein, we report a borane-promoted reductive deoxygenation coupling reaction to synthesize sulfides. This reaction features excellent functional group compatibility, high efficiency, broad substrate scope, and application in late-stage functionalization of biomolecules. Preliminary mechanistic studies suggest diaryl sulfides are the intermediates of this reaction. Moreover, the real active aryl sulfide anions may be generated in situ with the aid of B2pin2 and react with alkyl tosylates through a concerted SN2 pathway.
An efficient asymmetric alkenylation between 3-vinylindoles and isatin derivatives was developed under catalysis of a chiral copper complex. A series of optically active 3-alkenyl-3-substituted oxindoles were obtained in excellent yields and stereoselectivities. The reaction mechanism was proposed and supported by DFT calculation.
A stimuli-responsive supramolecular polymer network has been constructed based on the host-guest interactions between the copolymer poly-P[5]A with pendent pillararene units and bis(sulfonium) diction guest G2. The formation mechanism of the supramolecular polymer network has been explored by the intensive study. With the addition of the competitive molecules and heating, the supramolecular polymer network could be dissociated and lead to clear changes in NMR spectroscopy and viscosity property.
A calix[4]arene ligand assisted direct β-C−H arylation of tertiary aliphatic aldehydes has been developed via a Pd-catalyzed C(sp3)−H functionalization process. This strategy exhibited good functional group compatibility and C−H bond site-selectivity. Mechanism studies have shown that both synergistic effect and cationic-π supramolecular interaction between calixarene cavity and transition-metal catalytic center may play an important role in this catalytic cycle. This complementary method would be used in organic and medical chemistry due to the importance of tertiary aliphatic aldehydes.
A novel pillar[5]arene (P5DPB) that includes a classical π-conjugated molecule, 4,4'-(1,4-phenylenedi-2,1-ethenediyl) bis-pyridine (DPB), was designed and synthesized as a substituent. Because of this modification, P5DPB exhibits several unique properties that differ from those of common pillar[5]arenes. The P5DPB neutral pyridine shows good selectivity for Ag+ and Fe3+. The presence of Ag+ ions cause a blue shift (from yellow-green to green) and a decrease in the intensity of the P5DPB emission, while the addition of Fe3+ significantly quenches the P5DPB fluorescence. In addition, P5DPB satisfies the conditions for the construction of an energy transfer system with the commonly used Rhodamine B dye and shows great potential for the development of artificial light-harvesting systems. This work provides a new approach for the construction of energy transfer systems and a new reference for metal detection based on derivatized pillar[n]arenes, greatly enriching the applications of these systems.
Challenges of achieving efficient photodimerization of azaanthracene derivatives remain due to the low selectivity and slow reaction rate. In this paper, cucurbit[10]uril (CB[10]), with the largest rigid and hydrophobic cavity among CB[n]s, was used to affect the photodimerization reaction of four water-soluble 1-(2-)substituted azaanthracene derivatives (1-4). It revealed that 1-4 could form 1:2 host-guest complexes with CB[10] in aqueous solution. Irradiation of 1 in the presence of 0.5 equiv. of CB[10] selectively produced a head-to-tail (anti-HT) photodimer product. As for 2-4, CB[10] acted as a nanoreactor accelerating their photodimerization reaction in water. Our results suggest that photodimerization of azaanthracene derivatives could be promoted by the CB[10]-based host-guest strategy with high efficiency and selectivity.
The electrooxidative [3 + 2] annulation of amidines with 2-arylideneindane-1,3-diones or 4-alkylidene pyrazolones is reported using NaI as a redox catalyst and electrolyte under constant current electrolysis in an undivided cell. The current strategy features excellent functional group tolerance, simple operation, and mild conditions, thus providing an environmentally benign and efficient access to spiroimidazolines in moderate to good yields.
X-ray detection and imaging via scintillators has been utilized in missions worldwide within areas of scientific research, medical industry, military defense and homeland security. Commercial scintillators are costly with high energy consumption through the sintering. It is of great significance to seek alternative scintillating materials for sensitive X-ray detection in the next-generation. Herein, eight structure-defined Ln(Ⅲ)-based metal–organic frameworks (Ln-MOFs) were prepared, 2D [Ln2(1,4-ndc)3(DMF)4]n·nH2O (Ln = Sm 1, Eu 2, Dy 3, Tb 4) and 3D [Ln4(2,6-ndc)6(μ2H2O)2(H2O)4]n·2nH2O (Ln = Sm 5, Eu 6, Dy 7, Tb 8), where 1,4-H2ndc = 1,4-naphthalene dicarboxylate acid, 2,6-H2ndc = 2,6-napthalene dicarboxylate acid, DMF = N, N-dimethylformamide. Merely compounds 2 and 6 show remarkable X-ray scintillation performance via the characteristic red emissions of Eu(Ⅲ) ions, in which the absorbed energy from the triplet states of the organic moieties can be transferred more efficiently to the resonance emission levels of Eu(Ⅲ) ions than other lanthanide(Ⅲ) ions. The X-ray dosage rate detection limits of 2 and 6 are superior to the standard for the medical X-ray diagnosis dosage rate. As proofs-of-concepts, matrix-mixed membranes fabricated with 2 and 6 have achieved remarkable X-ray imaging with high resolution for practical object shooting.
In the design of conjugated molecules, modular production enables materials to easily realize structure modification and precisely tune their photoelectrical property. Construction of a novel and universal building block is crucial to design and manufacture high performance and stable conjugated molecules for optoelectronic application. Herein, we originally demonstrated a universal 4-qualifiable fluorene-based building block, which is a fundamental molecular segment to functionalize and obtain novel conjugated materials. Compared to the traditional modification at 9-site, additional 4-position functionalization provided an exciting blueprint to not only tune electronic structure and excited state via p-n molecular design engineering and space charge-transfer strategy, but also allow for optimizing intermolecular arrangement and obtaining solution-processing ability. The introduction of the 4-site substituent in fluorene based semiconductors may endow materials with unique properties. Finally, we successfully prepared two stable deep-blue light-emitting conjugated polymer, PODOPF and PODOF, by utilizing the 4-substituent fluorene based building block. It is believable that the performance, stability and processibility of reported outstanding fluorene-based conjugated molecules can be further optimized based on this universal building block.
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