Latest Articles3-CF3S substituted thioflavones and benzothiophenes were achieved via the reactions of AgSCF3 with methylthiolated alkynones and alkynylthioanisoles, respectively, promoted by persulfate. This protocol possesses good functional group tolerance and high yields. Mechanistic studies suggested that a classic two-step radical process was involved, which includes addition of CF3S radical to triple bond and cyclization with SMe moiety.
We studied the cascade nucleophilic addition reactions of 1,2,3-triazines with activated acetonitriles or ketones, which were used to construct highly substituted pyridines that are not easily accessed by conventional methods. The strategy addressed some structural diversity issues currently facing medicinal chemistry, and the resulting pyridines could be used as convenient precursors for the synthesis of related pharmaceuticals. In particular, our method was applied to the syntheses of the marketed drug etoricoxib and several biologically important molecules in a few steps.
In this work, a blue emitter with a 3D rigid structure composed of multiple spirobifluorene (3-Spiro) has been synthesized and characterized. Through a detailed study of the electrochemical and photophysical properties of 3-Spiro, we have evidenced that 3-Spiro can be applied as an active component of organic light-emitting diodes (OLEDs). The device with 5% doping rate of 4CzPNPh exhibits high external quantum efficiency (EQE) of 11%, which proves the potential of 3D rigid structure emitters for OLEDs.
The asymmetric synthesis of 16, 17, 20-epi-deserpidine and a derivative of (-)-deserpidine has been achieved. Key features in the assembly of the pentacyclic framework include a visible-light photocatalytic intra-/inter-/intramolecular radical cascade reaction to construct the tetracyclic ABCD ring system in one-pot and an intramolecularaldol reaction to forge the cyclohexane E ring.
A Pd-catalyzed enantioselective synthesis of 2-methyl-3-methyleneindoline in up to 89% yield and 84% ee from racemic vinyl benzoxazinanones has been developed with the help of (R,R)-BenzP* ligand. Mechanism studies support the formation of palladacyclobutane as the key intermediate via C2 attack to π-allyl Pd complex. The β-hydride elimination provides a new reaction pathway for the palladacyclobutane.
AA005 (1), a potent anticancer mimicking molecule of natural Annonaceous acetogenin, features a central C2-symmetric triglycol moiety and three stereogenic centers. To support ongoing animal studies, a scalable 10-step synthesis of AA005 (1) has been studied, optimized and accomplished in this work, starting from commercially available economic materials ethylene glycol and (R)-epichlorohydrin. A regio- and stereo-controlled BF3·Et2O-promoted epoxide opening of (R)-epichlorohydrin with ethylene glycol was investigated, optimized and successfully applied to the scalable preparation of the crucial fragment 6a with C2-symmetry. Further successive epoxide openings elaborated both two side chains and the whole skeleton with proper nucleophiles and electrophiles. Comparison and optimization of the reaction sequences finally led to completion of a new multi-gram synthesis of AA005 (1) with satisfactory enantiomeric and diastereomeric purity.
A Mn(Ⅲ) mediated radical reaction of new designed multi-functionalized 2-isocyano-6-alkenyl(alkynyl) benzonitriles with arylboronic acids has been developed. This reaction provides a method for the synthesis of pyrroloisoquinoline derivatives through the formation of two C—C bonds and one C—N bond via radical cascade cyclization in one step.
The synthesis of borylated organofluorines is of great interest due to their potential values as synthons in modular construction of fluorine-containing molecules. Reported herein is a rhodium-catalyzed hydroboration of aryl gem-difluoroalkenes leading to a series of α-difluoromethylated benzylborons. The use of cationic rhodium catalyst and a biphosphine ligand with large bite angle was crucial for reactivity by offering good regioselectivity and diminishing the undesired β-F elimination. Preliminary derivatizations of the products were conducted to showcase the utility of this protocol.
A novel BF3-promoted [3 + 2] annulation of azonaphthalenes and ynamides is described. This protocol provides a modular and efficient entry to functionalized amino benzo[e]indole derivatives smoothly.
Bis(4-fluorophenyl) substituted oxazole(2,5-Oxz) and C2(5)-C2'(5') linked bioxazole isomers(C2-C2'_BOxz, C2-C5'_BOxz and C5-C5'_BOxz) were concisely synthesized via palladium-catalyzed regioselective and sequential C—H arylation in 1–3 reaction steps along with 20%–83% of total yields from oxazole and 4-bromofluorobenzene.The linking orientation plays a key role in the packing geometry and photophysical properties of C2-C2'_BOxz, C2-C5'_BOxz and C5-C5'_BOxz. These bioxazole isomers in solid state showed significant differences in photoluminescence quantum yields (PLQY) (0.33, 0.25 and 0.04, respectively), delayed fluorescence properties and powder X-ray diffraction (PXRD) patterns, suggesting the divergence in intermolecular interactions. The theoretically calculated gradient isosurfaces and complexation energies indicate the existence of intense π-π interactions between molecular layers, which are in good agreement with the variation trend of optical properties.
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