N-Directed, Radical Relay Enantioconvergent Sulfinylation of Distal C(sp)-H Bonds via Cobalt Catalysis.

Cobalt-catalyzed enantioconvergent cross-coupling of C(sp)-H bonds with -generated sulfenate anions is achieved to access chiral sulfoxides, which are found in the structures of many biologically active agents. The more challenging aliphatic C-H bonds as well as sterically hindered substrates containing tertiary C-H bonds could also be tolerated well. Mechanistic studies indicate that the transformation could undergo a CoS(O)R-mediated single-electron transfer with -fluorocarboxamides, followed by a 1,5-hydrogen atom transfer and then a pivotal organocobalt(IV)-controlled enantioselective cross-coupling process.

Synthesis of dienes from pyrrolidines using skeletal modification.

Saturated N-heterocyclic pyrrolidines are common in natural products, medicinal compounds and agrochemicals. However, reconstruction of their skeletal structures creating new chemical space is a challenging task, and limited methods exist for this purpose. In this study, we report a skeletal modification strategy for conversion of polar cyclic pyrrolidines into nonpolar linear dienes through a N-atom removal and deconstruction process.

Design of oral English teaching model based on multi-modal perception of the Internet of Things and improved conventional neural networks.

Oral English instruction plays a pivotal role in educational endeavors. The emergence of online teaching in response to the epidemic has created an urgent demand for a methodology to evaluate and monitor oral English instruction. In the post-epidemic era, distance learning has become indispensable for educational pursuits.

Metal-to-Ligand Ratio-Dependent Chemodivergent Asymmetric Synthesis.

Chemodivergent asymmetric synthesis was achieved by tuning the metal-to-ligand ratio in an organometallic catalytic system. Using N-(aroyloxy)phthalimide as the precursor of either an oxygen-centered aroyloxy radical or a nitrogen-centered phthalimidyl radical, enantioselective oxocyanation or aminocyanation of alkenes was achieved separately through a dual photoredox and copper catalysis. The metal-to-ligand ratio can exert chemoselective control while retaining the high enantiopurity of divergent products.

N-Atom Deletion in Nitrogen Heterocycles.

Excising the nitrogen in secondary amines, and coupling the two residual fragments is a skeletal editing strategy that can be used to construct molecules with new skeletons, but which has been largely unexplored. Here we report a versatile method of N-atom excision from N-heterocycles. The process uses readily available N-heterocycles as substrates, and proceeds by N-sulfonylazidonation followed by the rearrangement of sulfamoyl azide intermediates, providing various cyclic products.

Silhouette-free image encryption using interference in the multiple-parameter fractional Fourier transform domain.

A novel approach for silhouette-free image encryption based on interference is proposed using discrete multiple-parameter fractional Fourier transform (DMPFrFT), which generalizes from fractional Fourier transform. An original image is firstly applied by chaotic pixel scrambling (CPS) and then encoded into the real part of a complex signal. Using interference principle, the complex signal generates three phase-only masks in DMPFrFT domain.

Photoredox-catalysed redox-neutral trifluoromethylation of vinyl azides for the synthesis of α-trifluoromethylated ketones.

A redox-neutral, mild, and simple protocol is developed for the synthesis of α-trifluoromethylated ketones from vinyl azides under transition-metal-free conditions. In the presence of organic photoredox catalyst N-methyl-9-mesityl acridinium and sodium trifluoromethanesulfinate, a broad range of substituted vinyl azides were found to react smoothly upon visible-light irradiation, readily furnishing the corresponding products in satisfied yields.

Selective histone deacetylase small molecule inhibitors: recent progress and perspectives.

Since the first pan-HDAC inhibitor SAHA was approved by U.S. FDA 10 years ago, HDACs including SIRT1-7 have received significant attention due to the fact that aberrant histone deacetylase activtiy has been implicated in a variety of human diseases, such as cancers, virus infection, and neurodegenerative diseases.

Lgr5 Methylation in Cancer Stem Cell Differentiation and Prognosis-Prediction in Colorectal Cancer.

Objective: Leucine-rich-repeat-containing G-protein-coupled receptor 5 (lgr5) is a candidate marker for colorectal cancer stem cells (CSC). In the current study, we investigated the methylation status within thelgr5 promoter and evaluated its relationship with CSC differentiation, prognosis for colorectal cancer, and its clinicopathological features.

Methods: The methylation status within Lgr5 promoter was detected with a methylation-specific PCR in six colorectal cancer cell lines as well as 169 primary colorectal tumor tissues.

Oxime-mediated facile access to 5-methylisoxazoles and applications in the synthesis of valdecoxib and oxacillin.

A palladium-catalyzed efficient synthesis of 5-methylisoxazoles via oxime-mediated functionalization of unactivated olefins is described. The reaction affords a variety of 5-methylisoxazoles in moderate to good yields. To further demonstrate the utility of the method, the rapid synthesis of valdecoxib and oxacillin is reported.

A novel mutation in the COL2A1 gene in a Chinese family with Spondyloepiphyseal dysplasia congenita.

Spondyloepiphyseal dysplasia congenita (SEDC) is an autosomal dominant skeletal dysplasia characterized by short stature, diminished joint mobility, dislocation of hip, absent femoral head ossification, scoliosis and flattened vertebral bodies. SEDC is caused by mutations in the gene encoding the type II procollagen α-1 chain (COL2A1). We screened COL2A1 gene mutations in four affected individuals from a Chinese family with SEDC.