Photoinduced Late-Stage Radical Decarboxylative and Deoxygenative Coupling of Complex Carboxylic Acids and Their Derivatives.

The simple and efficient conversion of carboxylic acids into structurally diverse organic molecules is highly desirable in chemical synthesis. This review covers recent developments in photocatalytic methodology for late-stage transformations of complex carboxylic acids and their derivatives enabled by radical decarboxylation and deoxygenation, highlighting some representative and significant contributions in this field. These advancements are categorized based on the reactivity patterns exhibited by the carboxylic acids.

Visible-light-enabled stereoselective synthesis of functionalized cyclohexylamine derivatives [4 + 2] cycloadditions.

An unprecedented intermolecular [4 + 2] cycloaddition of benzocyclobutylamines with α-substituted vinylketones, enabled by photoredox catalysis, has been developed. The current method enables facile access to highly functionalized cyclohexylamine derivatives that were otherwise inaccessible, in moderate to good yields with excellent diastereoselectivities. This protocol has some excellent features, such as full atom economy, good functional-group compatibility, mild reaction conditions, and an overall redox-neutral process.

Enantio- and Diastereoselective De Novo Synthesis of 3-Substituted Proline Derivatives via Cooperative Photoredox/Brønsted Acid Catalysis and Epimerization.

Herein, a novel strategy for the catalytic asymmetric synthesis of enantioenriched 3-- and 3--substituted prolines has been successfully established via an unprecedented cascade radical addition/cyclization enabled by synergistic photoredox/Brønsted acid catalysis and subsequent base-assisted epimerization. The current protocol provides a unique access to all four stereoisomers of 3-substituted prolines which are not readily achieved via currently established methods. This methodology could be further extended to the asymmetric synthesis of the full complement of stereoisomers of 3-substituted pipecolinic acids.

Trends of Ten Leading Causes of Death in Head and Neck Squamous Cell Carcinoma.

Objective: An understanding of the leading causes of death in patients with head and neck squamous cell carcinoma (HNSCC) would be helpful to inform doctors, patients, and healthcare providers on disease management. This study aimed to comprehensively study the leading causes of death in these survivors.

Methods: We investigated the trends of risk factors for major causes of death in patients with HNSCC.

Visible-Light-Enabled Enantioconvergent Synthesis of α-Amino Acid Derivatives via Synergistic Brønsted Acid/Photoredox Catalysis.

An unprecedented radical cross-coupling reaction was achieved between glycine esters and racemic α-bromoketones catalyzed by synergistic Brønsted acid/photoredox catalysis, thus serving as an efficient platform for the synthesis of highly valuable enantioenriched unnatural α-amino acid derivatives. This dual catalysis provides a powerful capability to control the reactive radical intermediate and iminium ion, thereby enabling enantioconvergent bond-formation in a highly stereochemical manner. An array of valuable enantioenriched unnatural α-amino acid derivatives bearing two contiguous stereogenic centers are readily accessible with high diastereoselectivity and excellent enantioselectivity, which include α-amino acids with a unique β-fluorinated quaternary stereocenter or its β-all-carbon counterpart.

Catalytic asymmetric de novo construction of dihydroquinazolinone scaffolds via enantioselective decarboxylative [4+2] cycloadditions.

The first de novo construction of enantioenriched dihydroquinazolinones via an intermolecular strategy has been established. This approach also represents the first catalytic asymmetric [4+2] cycloaddition of vinyl benzoxazinanones with sulfonyl isocyanates, which afforded chiral dihydroquinazolinones in high yields and excellent enantioselectivities (up to 98% yield, 99 : 1 er). This reaction not only confronts the great challenge in de novo construction of enantioenriched dihydroquinazolinone skeletons, but also advances the chemistry of decarboxylative cycloadditions involving vinyl benzoxazinanones.

UV-Vis Spectrum Characteristics of Phycocyanin Purification in Water from Chao Lake.

Fresh blue algal from Chao Lake was used in this study. The crude extracts of phycocyanin were obtained with freeze-thaw method. The purification of phycocyanin was performed by combining two-step salt precipitation and two-step column chromatography.

Method for Aluminum Oxide Thin Films Prepared through Low Temperature Atomic Layer Deposition for Encapsulating Organic Electroluminescent Devices.

Preparation of dense alumina (Al₂O₃) thin film through atomic layer deposition (ALD) provides a pathway to achieve the encapsulation of organic light emitting devices (OLED). Unlike traditional ALD which is usually executed at higher reaction n temperatures that may affect the performance of OLED, this application discusses the development on preparation of ALD thin film at a low temperature. One concern of ALD is the suppressing effect of ambient temperature on uniformity of thin film.