Palladium/Norbornene-Catalyzed Decarbonylative Difunctionalization of Thioesters.

The transition-metal-catalyzed decarboxylation of aryl carboxylic acids has drawn significant attention as an efficient and practical tool for the synthesis of substituted arenes. However, the decarboxylative construction of polysubstituted arenes with different contiguous substituents has not been widely reported. Herein, we describe a novel decarbonylative Catellani reaction via palladium-catalyzed, norbornene (NBE)-mediated polyfunctionalization of aromatic thioesters, which serve as readily available carboxylic acid derivatives. A variety of alkenyl, alkyl, aryl, and sulfur moieties could be conveniently introduced into the ipso-positions of the aromatic thioesters. By combining carboxyl-directed C-H functionalization and the classical Catellani reaction, our protocol allows for the construction of 1,2,3-trisubstituted and 1,2,3,4-tetrasubstituted arenes from simple aromatic acids. Furthermore, the late-stage functionalization of a series of drug molecules highlights the potential utility of the reaction.

C3-Arylation of indoles with aryl ketones via C-C/C-H activations.

C3-Arylation of indoles with aryl ketones is accomplished via palladium-catalyzed ligand-promoted Ar-C(O) cleavage and subsequent C-H arylation of indole. Various (hetero)aryl ketones are compatible in this reaction, affording the corresponding 3-arylindoles in moderate to good yields. Further introduction of an indole moiety into the natural products desoxyestrone and evodiamine demonstrate the synthetic utility of this protocol.

Pd-Catalyzed Asymmetric Acyl-Carbamoylation of an Alkene to Construct an α-Quaternary Chiral Cycloketone.

Herein, we report the palladium-catalyzed asymmetric acyl-carbamoylation of an alkene by employing thioesters as the acyl electrophiles and t-BuNC as the carbamoyl reagent, affording an α-quaternary chiral cycloketone in synthetically useful yields with excellent enantioselectivity. The reaction proceeded via asymmetric 1,2-migratory insertions of acyl-Pd into alkenes and subsequent migratory insertion of isocyanides into C(sp3)-PdII. The product could be diversified to some valuable skeletons with retention of enantiopurity, demonstrating the synthetic utility of this protocol.

Construction of 2-alkynyl aza-spiro[4,5]indole scaffolds via sequential C-H activations for modular click chemistry libraries.

Herein, we have developed a strategy of sequential C-H activations of indole to construct novel 2-alkynyl aza-spiro[4,5]indole scaffolds, which incorporated both alkyne and spiro-units into indole. Gram-scale synthesis and a one-pot, three-step synthesis demonstrated the utility of this protocol. Hybrid conjugates with an oseltamivir derivative further offered a powerful tool for the construction of a versatile spiroindole-containing library via click chemistry.

Correction to: Identifying the active components of Baihe-Zhimu decoction that ameliorate depressive disease by an effective integrated strategy: a systemic pharmacokinetics study combined with classical depression model tests.

[This corrects the article DOI: 10.1186/s13020-019-0254-9.].

Systematic investigation on the chemical basis of anti-NAFLD Qushi Huayu Fang. Part 1: A study of metabolic profiles in vivo and in vitro by high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry.

Qushi Huayu Fang (QHF) is a clinic-empirical prescription for treating non-alcoholic fatty liver disease (NAFLD) in China, which is composed of five herbs. However, the bioactive constituents responsible for the efficacy of QHF remain unclear. Thus, a high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry method was established and adopted to identify the constituents of QHF, and profile its metabolism in vivo and in vitro. Among the 66 constituents in QHF, only 14 compounds of six structural types were absorbed, and 34 metabolites were generated through eight metabolic pathways. A total of 20 metabolites were first reported, including four organic acids, one iridoid, two flavones, five naphthols, three anthraquinones, and five stilbenes. Glucuronidation and sulfation were the main metabolic pathways, and the intestinal metabolism played an important role in the biotransformation of QHF. Many compounds, especially those detected in the liver, the target organ of QHF, were reported to display the anti-NAFLD activity. This is the first study to explore the constituents of QHF and its metabolism in vivo and in vitro, thus realizing the first step to clarify the chemical basis of QHF qualitatively, and laying the foundation for further research on the anti-NAFLD mechanism of QHF.

Identifying the active components of Baihe-Zhimu decoction that ameliorate depressive disease by an effective integrated strategy: a systemic pharmacokinetics study combined with classical depression model tests.

BACKGROUND: Modern pharmacological studies have demonstrated that Baihe-Zhimu decoction (BZD) has antidepressant effects. However, the complex composition and lack of clear evaluation standards for BZD make it less likely to be understood and accepted than evidence-based active natural compounds. METHODS: In this study, an effective method for the identification of antidepressant components was demonstrated and applied to BZD. The first step was to evaluate the efficacy of BZD by the forced swimming test (FST) and the tail suspension test (TST), followed by successive quantitative analyses of the absorbed constituents at different stages, such as before hepatic disposition, liver distribution, after hepatic disposition and brain distribution after the oral administration of BZD. Finally, the compounds detected in the brain were confirmed by activity testing. RESULTS: Our investigation observed that timosaponin BII and timosaponin BIII were accurately determined in the brain after oral administration of BZD, and they were further confirmed to reduce the immobility time in the FST and TST. As described above, timosaponin BII and timosaponin BIII were used to scientifically and reasonably explain the effective chemical basis of the effect of BZD on depression. CONCLUSIONS: This research affords an effective method to discover lead molecules for antidepressants from traditional Chinese medicine.

Asymmetric Synthesis of the C15⁻C32 Fragment of Alotamide and Determination of the Relative Stereochemistry.

Alotamide is a cyclic depsipetide isolated from a marine cyanobacterium and possesses a unique activation of calcium influx in murine cerebrocortical neurons (EC50 4.18 µM). Due to its limited source, the three stereocenters (C19, C28, and C30) in its polyketide fragment remain undetermined. In this study, the first asymmetric synthesis of its polyketide fragment was achieved. Four relative possible diastereomers were constructed with a boron-mediated enantioselective aldol reaction and Julia⁻Kocienski olefination as the key steps. Comparison of 13C NMR spectra revealed the relative structure of fragment C15⁻C32 of alotamide.