A Pd-catalyzed amide-directed enantioselective hydrocarbofunctionalization of unactivated alkenes with C-H nucleophiles has been developed using a chiral monodentate oxazoline (MOXin) ligand. Various indoles react at C3 position with aminoquinoline-coupled 3-alkenamides to give γ addition products in good to excellent yield and enantioselectivity. This study represents an important advance of the development of chiral monodentate oxazoline ligands, which have been underexplored for asymmetric catalysis.

β-Lactams are important scaffolds in drug design and frequently used as reactive intermediates in organic synthesis. Catalytic reactions featuring intramolecular C–H amidation of alkyl carboxamide substrates could provide a straightforward disconnection strategy for β-lactam synthesis. Herein, we report a streamlined method for asymmetric synthesis of β-aryl β-lactams from propanoic acid and aryl iodides via Pd-catalyzed sequential C­(sp3)–H functionalization. The lactam-forming reaction provides an example of PdII-catalyzed enantioselective intramolecular C­(sp3)–H amidation reaction and proceeds up to 94% ee. The use of a 2-methoxy-5-chlorophenyl iodide oxidant is critical to control the competing reductive elimination pathways of the PdIV intermediate to achieve the desired chemoselectivity. Mechanistic studies suggest that both steric and electronic effects of the unconventional aryl iodide oxidant are responsible for controlling the competing C–N versus C–C reductive elimination pathways of the PdIV intermediate.

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A new enantioselective palladium(II)-catalyzed benzylic C-H arylation reaction of amines is enabled by the bidentate picolinamide (PA) directing group. This reaction provides the first example of enantioselective benzylic γ-C-H arylations of alkyl amines, and proceeds with up to 97 % ee. The 2,2'-dihydroxy-1,1'-binaphthyl (BINOL) phosphoric acid ligand, Cs CO , and solvent-free conditions are essential for high enantioselectivity. Mechanistic studies suggest that multiple BINOL ligands are involved in the stereodetermining C-H palladation step.

Pu-erh tea is a popular beverage in Southeast Asia, especially in many areas of China. Natural fungal inoculation and fermentation form its special quality and function in health care. At the same time, a common assumption is that unknown fungi from natural inoculation may pose a risk for safety of drinking the beverage, leading to an urgent need for a thorough fungal survey of Pu-erh tea. The present paper reports the natural fungal colonizations isolated from 60 representative samples. The results of the survey showed that the fungal colonizations were isolated from all the samples studied, ranging from 1.6 ¥ 10 3 to 1.16 ¥ 10 5 cfu/g, and 62 isolates were identified to belong to 41 species of 19 genera, including 13 species of Aspergillus and seven species of Penicillium, and 21 species of other genera. The predominant fungi were yeasts and different species of the genus Aspergillus. The concrete species of the dominant fungi varied with environment conditions of various production places. Sample parameters such as water content, A W , pH, polyphenol content were recorded, though they appeared to have no obvious effects on the total number of fungi, whereas processing and storage methods evidently affected total number of fungi. Some species of fungi such as Aspergillus fumigatus, Penicillium spp., Trichoderma spp. and Fusarium culmorum, etc., which maybe excrete toxic metabolites, were isolated in the survey. Further evaluation on the safety of these fungi isolated from Pu-erh tea products is needed. PRACTICAL APPLICATIONSThis study investigated the fungal colonizatins exisiting in Pu-erh tea and some parameters concerning the storage of Pu-erh tea. These findings will help 3 Corresponding

Our results demonstrated that headspace solid-phase microextraction/GC-MS/GC-O was a fast approach for isolation and quantification aroma-active compounds. The PLSR method was also considered to be a useful tool in selecting important variables for sensory attributes. These two strategies, which allowed us to comprehensively evaluate the sensorial contribution of a single volatile from different perspectives, can be applied to related products for comprehensive quality control. © 2018 Society of Chemical Industry.

A recently developed method enabled us to simultaneously characterize and quantitate glycosidically bound volatiles (GBVs) at picomole levels using liquid chromatography-mass spectrometry (LC-MS). On the basis of the analytical data it is possible to screen tea varieties most suitable for black tea processing, in which higher concentrations of primeverosides accumulate. The primeverosides decreased at the rolling step in black tea processing, whereas the glucopyranosides did not change much. The total contents of GBVs gradually increased at the withering steps and then remarkably increased after the fixing step at 230 °C, during oolong tea processing. The presence of 6'-O-malonyl ester type β-D-glucopyranosides in the tea samples suggested a contribution to the increment in glucopyranosides during oolong tea processing. The method was also used to analyze GBVs and their derivatives to understand their possible role in the metabolic pathway of tea.

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