Postoperative infections remain a risk factor that leads to failures in oral and maxillofacial artificial bone transplantation. This study aimed to synthesize and evaluate a novel hydroxyapatite whisker (HAPw) / nano zinc oxide (n-ZnO) antimicrobial bone restorative biomaterial. A scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and x-ray diffraction (XRD) were employed to characterize and analyze the material. Antibacterial capabilities against Staphylococcus aureus, Escherichia coli, Candida albicans and Streptococcus mutans were determined by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), and kinetic growth inhibition assays were performed under darkness and simulated solar irradiation. The mode of antibiotic action was observed by transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). The MIC and MBC were 0.078-1.250 mg ml(-1) and 0.156-2.500 mg ml(-1), respectively. The inhibitory function on the growth of the microorganisms was achieved even under darkness, with gram-positive bacteria found to be more sensitive than gram-negative, and enhanced antimicrobial activity was exhibited under simulated solar excitation compared to darkness. TEM and CLSM images revealed a certain level of bacterial cell membrane destruction after treatment with 1 mg ml(-1) of the material for 12 h, causing the leakage of intracellular contents and bacteria death. These results suggest favorable antibiotic properties and a probable mechanism of the biomaterial for the first time, and further studies are needed to determine its potential application as a postoperative anti-inflammation method in bone transplantation.

The stereodivergent iridium‐catalyzed allylic alkylation and fluorination of acyclic ketones is described. α‐Pyridyl‐α‐fluoroketones with vicinal tertiary and quaternary stereocenters were obtained in moderate to excellent yields and stereoselectivities. Distinct from known stereodivergent synthesis, for which two different chiral catalysts are required in general, herein we report a sequence‐dependent stereodivergent synthesis. With only a single chiral Ir catalyst, all four possible stereoisomers of the products were prepared from the same starting materials by simply adjusting the sequence of asymmetric allylic alkylation and fluorination and varying the absolute configuration of the Ir catalyst.

Ketones and aldehydes are employed as enol O-nucleophiles in an iridium-catalyzed asymmetric allylic substitution reaction. The reaction proceeds well in the presence of a well-defined chiral iridium complex under mild conditions. A series of chiral 2H-1,4-oxazine skeletons can be obtained in up to 94% yield with 99% ee. The utility of this novel method has been demonstrated by its implementation in the first enantioselective synthesis of (+)-chelonin A.

Asymmetric ring-opening of 7-oxabenzonorbornadienes is achieved via Co-catalyzed indole C–H functionalization. The utilization of chiral Co-catalyst consisting of a binaphthyl-derived trisubstituted cyclopentadienyl ligand resulted in high yields (up to 99%) and excellent enantioselectivity (>99% ee) for the target products with tolerance for diverse functional groups. Opposite diastereoselectivities are obtained with chiral Co-catalyst or Cp*CoI2CO. Combined experimental and computational studies suggest β-oxygen elimination being the selectivity-determining step of the reaction. Meanwhile, the reactions of 7-azabenzonorbornadiene could also be executed in a diastereodivergent manner.

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Spirocyclic hexadienones with multiple stereogenic centers are frequently found in natural products but remain challenging targets to synthesize. Herein, we report the enantioselective desymmetrization of bisphenol derivatives via Ir-catalyzed allylic dearomatization reactions, affording spirocyclic hexadienone derivatives with up to three contiguous stereogenic centers in good yields (up to 90%) and excellent enantioselectivity (up to 99% ee). The high efficiency of this reaction is exemplified by the short reaction time (30 min), low catalyst loading (down to 0.2 mol %), and ability to perform the reaction on a gram-scale. The total syntheses of (+)-tatanan B and (+)-tatanan C were also realized using this Ir-catalyzed allylic dearomatization reaction as a key step.

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