Latest ArticlesThe development of new carbon dots (CDs) for fluorescence-based cancer diagnosis has recently attracted extensive attention. Diagnosis methods based on ligand-receptor fluorescence suffer from the heterogeneity of receptor expression. Changes in the microenvironments of cancer cells provide opportunities for accurate and broad-spectrum cancer diagnosis. The lysosomes in cancer cells have lower polarity and higher viscosity than normal cells. Based on these two key microenvironmental parameters, dual-responsive CDs with inherent lysosome-targeting ability were synthesized via one-step hydrothermal treatment. The CDs exhibit many advantageous properties including facile synthesis, good water solubility, pH-independent emission, excellent photostability, good biocompatibility, and wash-free imaging ability. The CDs were successfully employed in the fluorescence-based discrimination of a broad spectrum of cancer cells from normal cells with high contrast. The CDs are promising candidates for use in the field of cancer diagnosis.
Ni(0)-catalyzed regio- and diastereodivergent [4 + 2] annulation of biphenylenes with α, β unsaturated ketones is described. This solvent-controlled diastereodivergent reaction integrates C-C bond cleavage of biphenylene and C=C double bond insertion selectivity, offering a mild approach to all possible diastereoisomers of 9, 10-dihydrophenanthrene derivatives from the same starting materials.
The construction of secondary alkylsilanes is a challenging subject in the synthetic community. The cross-coupling provides a practical solution to address this problem, but it typically relies on organometallic species. Herein, we report an Mn-mediated reductive C(sp3)–Si coupling to synthesize these compounds from alkyl and silyl electrophiles. This approach avoids the requirement for activation of Si–Cl by transition metals and thus allows for the coupling of various common chlorosilanes. The reaction proceeds under mild conditions and shows good functional group compatibility. The method offers access to α-silylated organophosphorus and sulfones with a scope that is complementary to those obtained from the established methods.
Recently, exploiting a novel supramolecular fabrication pathway have drawn great attention. To this endeavor, we firstly designed and reported an original light-activated platform based on the internal-driven forces of macrocyclic host by hiring the pillar[5]arene as the host molecule (H) and phenazine derivatives acting as an energetic guest molecule (G). Surprisingly, after adding the H solution into G system, the intensive fluorescence emission of the G molecule rapidly decreased under the irradiation of the UV-light (254 nm) until absolutely quenching. Delightfully, different from the traditional supramolecular host-guest interaction, the fluorescent emission of G molecule could be recovered after irradiating under the nature light. In view of this interesting observations, the interaction mechanism was carefully investigated by a series of characterizations. Those results suggested that the G molecule was easily threaded into the macrocyclic cavity (H) under the internal-driven forces induced by the UV-light irradiation, forming a 1:1 host-guest complex. Moreover, taking advantage of this especial feature, the light-activated platform of host–guest complex was further applied for ink-free light-driven printing materials, exhibiting great potential in the real application.
A green and highly efficient strategy for the preparation of bridged spirocyclic compounds via visible-light-induced cyclization of 2-(2-(arylethynyl)benzylidene)malononitrile derivatives with 2,6-di(tert-butyl)-4-methylphenol (BHT) at room temperature was developed. The photoinduced radical reactions generated the corresponding products in good yields under simple and mild reaction conditions.
An SN2-based photochemical strategy using dithiocarbamate anion as catalyst was developed for the activation of benzyl halides, which are extremely challenging to be applied as radical precursors in visible light photocatalysis. With this transition-metal-free and oxidant-free protocol, the benzylation (or cyanomethylation) of various heterocycles including quinoxalin-2(1H)-ones, coumarin, 2-phenyl-2H-indazole, 1-methyl-5-phenylpyrazin-2(1H)-one, 1-(fluoromethyl)cinnolin-4(1H)-one, and 2, 4-dibenzyl-1,2,4-triazine-3,5(2H, 4H)‑dione could be realized (46 examples, up to 98% yield). Importantly, some biologically relevant 3-benzylquinoxalin-2(1H)-ones were also be synthesized under mild conditions.
The concise syntheses of eight 13-methylprotoberberine (13-MePB) and eight enantioenriched 13-methyltetrahydroprotoberberine (13-MeTHPB) alkaloids have been achieved in a tactically modular fashion. This synthetic work features a one-pot metal-free Pictet-Spengler/Friedel-Crafts hydroxyalkylation/dehydration/oxidation sequence and a following highly enantioselective Ir-catalyzed hydrogenation. Given such brevity and modularity, our developed synthetic route would be greatly beneficial to the efficient syntheses of existing natural products and new fully synthetic variants of 13-MePB and 13-MeTHPB family.
Herein, we report a highly efficient versatile synthetic route to Chiraphos derivatives through Rh/Ph-bod catalyzed asymmetric addition of aryl boronic acids to phosphinyl dienes. Various substituted phosphinyl dienes, both on the parent skeleton and the phosphine atoms, were well tolerated with this method and provided chiral phosphine oxides in satisfied yield and up to 95% ee. The corresponding Chiraphos derivative displayed an advantage over Chiraphos in the representative Pd-catalyzed asymmetric 1,4-addition reaction.
By using a perylene diimine (PDI) syn-atropisomer as highly preorganized precursor, we successfully constructed a visible-light-active organic macrocycle PDI-M. The formation of macrocyclic structure effectively avoids self-aggregation of PDI cores and enhances the absorption in visible region. As a photocatalyst, PDI-M exhibits excellent activity on aerobic selective oxidation of sulfide into sulfoxide under visible light irradiation at room temperature. Mechanism studies show that both superoxide and singlet oxygen act as reactive oxygen species. This work provides a typical case toward the maximum utilization of photosensitive groups under mild conditions.
Highly enantioselective Rh-catalyzed partial hydrogenation of unprotected simple 2-alkyl-5-aryl-disubstituted pyrroles has been successfully developed, generating a series of chiral 1-pyrroline derivatives generally with excellent results (95%–99% yields, 91%–96% ee). Moreover, 2,5-aryl-1H-pyrroles were hydrogenated well in high yields and good enantioselectivities. This efficient protocol features easily accessible substrates, wide substrate scope, well functional group compatibility, commercially available rhodium precursor and chiral ligand. It provides a versatile route to access chiral 1-pyrroline derivatives that are of great importance in organic synthesis and pharmaceutical chemistry.
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