Photocatalytic Z/E isomerization unlocking the stereodivergent construction of axially chiral alkene frameworks.

The past century has witnessed a large number of reports on the Z/E isomerization of alkenes. However, the vast majority of them are still limited to the isomerization of di- and tri-substituted alkenes. The stereospecific Z/E isomerization of tetrasubstituted alkenes remains to be an underdeveloped area, thus lacking in a stereodivergent synthesis of axially chiral alkenes. Herein we report the atroposelective synthesis of tetrasubstituted alkene analogues by asymmetric allylic substitution-isomerization, followed by their Z/E isomerization via triplet energy transfer photocatalysis. In this regard, the stereodivergent synthesis of axially chiral N-vinylquinolinones is achieved efficiently. Mechanistic studies indicate that the benzylic radical generation and distribution are two key factors for preserving the enantioselectivities of axially chiral compounds.

Natural products reverse cancer multidrug resistance.

Cancer stands as a prominent global cause of death. One of the key reasons why clinical tumor chemotherapy fails is multidrug resistance (MDR). In recent decades, accumulated studies have shown how Natural Product-Derived Compounds can reverse tumor MDR. Discovering novel potential modulators to reduce tumor MDR by Natural Product-Derived Compounds has become a popular research area across the globe. Numerous studies mainly focus on natural products including flavonoids, alkaloids, terpenoids, polyphenols and coumarins for their MDR modulatory activity. Natural products reverse MDR by regulating signaling pathways or the relevant expressed protein or gene. Here we perform a deep review of the previous achievements, recent advances in the development of natural products as a treatment for MDR. This review aims to provide some insights for the study of multidrug resistance of natural products.

Asymmetric Allylic Substitution-Isomerization for the Modular Synthesis of Axially Chiral N-Vinylquinazolinones.

Axially chiral N-substituted quinazolinones are important bioactive molecules, which are presented in many synthetic drugs. However, most strategies toward their atroposelective synthesis are mainly limited to the axially chiral arylquinazolinone frameworks. The development of modular synthetic methods to access diverse quinazolinone-based atropisomers remains scarce and challenging. Herein, we report the regio- and atroposelective synthesis of axially chiral N-vinylquinazolinones via the strategy of asymmetric allylic substitution-isomerization. The catalysis system utilized both asymmetric transition-metal catalysis and organocatalysis to efficiently afford trisubstituted and tetrasubstituted N-vinylquinazolinone atropisomers, respectively. With the meticulous design of ß-substituted allylic substrates, both Z- and E-tetrasubstituted axially chiral N-vinylquinazolinones were obtained in good yields and high enantioselectivities.

[Pharmacokinetic study of Polydopamine Guttate Pills loaded with active components of Sarcandrae Herba in rats].

An ultra-high performance liquid chromatography-tandem mass spectrometry(UHPLC-MS/MS) method was established for the determination of active components of Sarcandrae Herba, and applied to the pharmacokinetics study of multiple dosage forms. After SD rats were administered by gavage with three dosage forms [Sarcandrae Herba extract, commercial Sarcandrae Herba Guttate Pills, and polydopamine guttate pills loaded with active components of Sarcandrae Herba(PDA-Sg Guttate Pills)], blood samples were collected from the inner canthus at different time points. After protein precipitation, plasma samples were separated on ACQUITY UPLC C_(18) column(2.1 mm×100 mm, 1.7 µm). The mobile phase consisted of water containing 0.2% formic acid and acetonitrile in gradient elution. The negative ions were measured simultaneously in the multi-reaction monitoring(MRM) mode. The pharmacokinetic parameters were calculated and fitted by DAS 2.0. All four components could be detected in the plasma of rats in each group at each time point except the neochlorogenic acid and cryptochlorogenic acid in the Sarcandrae Herba extract group. The guttate pills group showed a significant increase in drug content at each time point. The exposure of the main components of Sarcandrae Herba in blood was effectively increased by PDA-drug loading effect in PDA-Sg Guttate Pills(The AUC_(0-24 h) of neochlorogenic acid, cryptochlorogenic acid, isaziridin and rosmarinic acid reached 2.45, 32.90, 1.54, 4.81 times that of the commercial guttate pills). This study proves the measurability of the above-mentioned multi-component in vitro-in vivo delivery process. The pharmacokinetic study has shown that PDA-Sg Guttate Pills can effectively delay the elimination time and improve the bioavailability of the four components, which can provide theoretical data for the production of the drug.

Synergistic Pd/Cu-catalysed regio- and stereoselective borylation of allenylic carbonates.

A simple Pd/Cu-catalyzed borylation of allenylic carbonates with B2Pin2 was developed using a cheap P(OEt)3 ligand. Under mild neutral conditions, 2-boryl 1,3-butadienes were obtained selectively in moderate to high yields. Furthermore, the use of different diboron reagents was also feasible in the reaction.