Electrooxidative Rhodium(III)/Chiral Carboxylic Acid-Catalyzed Enantioselective C-H Annulation of Sulfoximines with Alkynes.

The combination of achiral Cp*Rh(III) with chiral carboxylic acids (CCAs) represents an efficient catalytic system in transition metal-catalyzed enantioselective C-H activation. However, this hybrid catalysis is limited to redox-neutral C-H activation reactions and the adopt to oxidative enantioselective C-H activation remains elusive and pose a significant challenge. Herein, we describe the development of an electrochemical Cp*Rh(III)-catalyzed enantioselective C-H annulation of sulfoximines with alkynes enabled by chiral carboxylic acid (CCA) in an operationally friendly undivided cell at room temperature. A broad range of enantioenriched 1,2-benzothiazines are obtained in high yields with excellent enantioselectivities (up to 99 % yield and 98 : 2 er). The practicality of this method is demonstrated by scale-up reaction in a batch reactor with external circulation. A crucial chiral Cp*Rh(III) intermediate is isolated, characterized, and transformed, providing rational support for a Rh(III)/Rh(I) electrocatalytic cycle.

Flavobacterium arsenatis sp. nov., a novel arsenic-resistant bacterium from high-arsenic sediment.

A novel bacterial strain Z(T) was isolated from the high-arsenic sediment in Jianghan Plain, China. The strain was Gram-staining-negative, rod-shaped and formed yellow colonies. This bacterium is capable of tolerating arsenate and arsenite, with MICs of 40 mM and 20 mM, respectively. The strain also possesses catalase and does not produce oxidase. The nucleotide sequence of the 16S rRNA gene of the isolate showed the highest similarity (96.9%) to that of the type strain of Flavobacterium soli. On the basis of the 16S rRNA gene sequence analysis and the phenotypic properties of strain Z(T), it was assigned to the genus Flavobacterium. The major respiratory menaquinone was MK-6 and the predominant fatty acids were iso-C15:0, summed feature 3 (containing C16:1ω6c and/or C16:1ω7c) and iso-C15:1G. The major polar lipids were phosphatidylethanolamine, three uncharacterized aminophospholipids and four unidentified phospholipids. The DNA G+C content was 32.1 mol%. Based on the phenotypic and genotypic data presented in this article, it can be concluded that this isolate represents a novel species of the genus Flavobacterium, for which the name Flavobacterium arsenatis sp. nov. is proposed. The type strain is Z(T) ( = CCTCC AB 2013048(T) = KCTC 32397(T)).

Pd-Catalyzed Atroposelective C-H Olefination: Diverse Synthesis of Axially Chiral Biaryl-2-carboxylic Acids.

Axially chiral carboxylic acids are important motifs in chiral catalysts and ligands. We herein reported the synthesis of axially chiral carboxylic acids via Pd(II)-catalyzed atroposelective C-H olefination using carboxylic acid as the native directing group. A broad range of axial chiral biaryl-2-carboxylic acids were synthesized in good yields with high enantioselectivities (up to 84% yield with 99% ee). Gram-scale reaction and further transformation reactions also provide a platform for synthetic applications of this method.