Temperature-Controlled Chemoselective Couplings of Alkyl Halides with Disulfides.

An unprecedented, transition metal-free -alkylation of disulfides with alkyl halides is developed for the first time, providing an efficient and green synthesis of thioethers and even thioesters. Notably, this new method allows the full utilization of both sulfur atoms of disulfides under chemical reductant-free conditions and can be easily scaled up in gram scale, showing good practical value. Control experiments suggested that water, unprecedentedly, serves as the terminal reductant of the whole reaction.

Identification and Functional Analysis of Three Genes in .

The Cleavage Stimulation Factor (CstF) complex, consisting of three subunits, is essential for the 3' end processing of precursor messenger RNA (pre-mRNA). In mammals, this complex includes CstF50, CstF64, and CstF77, named according to their molecular weights, and these proteins are conserved across many organisms. However, the functional roles of the three CstF genes (, , and ) in , a major rice pest, have not been fully explored.

Synthesis of hydroxy-thiazoline substituted pyridine derivatives [3 + 2] annulation of 1,4-dithiane-2,5-diol with cyanopyridine.

A series of hydroxy-thiazoline substituted pyridine compounds were synthesized the annulation of 1,4-dithiane-2,5-diol with cyanopyridine catalyzed by organic bases. The yields could reach up to 95%. The reaction required no solvent, and the products were obtained from raw materials and catalysts simply by grinding the mixture at room temperature for 10 min.

Clinical study of reoperation for acute type A aortic dissection.

Objective: The initial operation for type A aortic dissection has limitations, and there may be a need for reoperation in cases such as giant pseudoaneurysm formation and reduced blood supply to the distal vessels. In this study, we collected case data of patients who underwent cardiac major vascular surgery at our hospital to analyze the effectiveness of reoperation treatment options for type A aortic dissection and to summarize our treatment experience.

Method: Between June 2018 and December 2022, 62 patients with type A aortic dissection (TAAD) underwent reoperation after previous surgical treatment.

Carotid-subclavian bypass and endovascular aortic repair of Kommerell's diverticulum with aberrant left subclavian artery: A case report.

Background: Kommerell's diverticulum (KD) with aberrant left subclavian artery is a rare congenital deformity and also has very little research literature about it (35% of case study). There are three types of aortic arch diverticulum. Even literature concerning the treatment options are limited.

Debranching abdominal aortic hybrid surgery for aortic diseases involving the visceral arteries.

Objective: Aortic diseases involving branches of the visceral arteries mainly include thoracoabdominal aortic aneurysm (TAAA), aortic dissection (AD) and abdominal aortic aneurysm (AAA). The focus of treatment is to reconstruct the splanchnic arteries and restore blood supply to the organs. Commonly used methods include thoracoabdominal aortic replacement, thoracic endovascular aortic repair and hybrid approaches.

Unprecedented observation and characterization of sulfur-centred bifurcated hydrogen bonds.

Owing to the small electronegativity of the sulfur atom, it is commonly supposed that at most one weak H-bond can be formed between a sulfur atom and an H-bond donor. In this paper, an unprecedented 2 : 1 binding species generated from two molecules of phenol and a molecule of thioether was observed and characterized by various nuclear magnetic resonance (NMR) techniques, Fourier transform-infrared (FT-IR) techniques and density functional theory (DFT) calculations, revealing the formation of sulfur-centred O-H⋯S⋯H-O bifurcated H-bonds. This work may provide a simple and efficient method for the quantitative analysis of weak H-bonds between small organic molecules.

Synthesis of remote fluoroalkylated alkenes by a palladium-catalyzed relay Heck-type reaction.

Herein, we report a palladium-catalyzed relay Heck-type reaction of fluoroalkyl bromide and terminal alkenes. The reaction involves fluoroalkylation of alkenes and migration of double bonds via a 1,5-hydrogen atom transfer strategy. Through this method, a series of remote fluoroalkylated alkenes was obtained under mild conditions.

Insights into Substrate Self-Assisted Activation of Allylic Alcohols Guiding to Mild Allylic Substitution of Tautomerizable Heteroarenes.

A substrate self-assisted activation of allylic alcohols by tautomerizable heteroarenes via hydrogen bonding was disclosed by various NMR techniques, including variable-temperature H NMR, Job plot, and H NMR titration. Guided by these finding, a much milder allylic substitution of tautomerizable heteroarenes with allylic alcohols was developed, affording the target products in high yields.

Promoting Effect of Crystal Water Leading to Catalyst-Free Synthesis of Heteroaryl Thioether from Heteroaryl Chloride, Sodium Thiosulfate Pentahydrate, and Alcohol.

It is observed the crystal water in sodium thiosulfate pentahydrate (NaSO·5HO) can promote its multicomponent reaction with heteroaryl chlorides and alcohols, providing a facile, green, and specific synthesis of unsymmetrical heteroaryl thioethers via one-step formation of two C-S bonds under catalyst-, additive-, and solvent-free conditions. Mechanistic studies suggest that the crystal water in NaSO·5HO is crucial in generating the key thiol intermediates and byproduct NaHSO, which then catalyzes the dehydrative substitution of alcohols with thiols to afford thioethers.

Chemoselective Mono- and Difluorination of 1,3-Dicarbonyl Compounds.

By altering the amount of Selectfluor, the highly selective mono- and difluorination of 1,3-dicarbonyl compounds has been achieved, affording a variety of 2-fluoro- and 2,2-difluoro-1,3-dicarbonyl compounds in good to excellent yields. The reaction can be readily performed in aqueous media without any catalyst and base, which features practical and convenient fluorination. Importantly, a gram-scale reaction, transformation of 2-fluoro-1,3-diphenylpropane-1,3-dione to 4-fluoro-1,3,5-triphenyl-1-pyrazole, and chlorination and bromination of 1,3-dicarbonyl compounds are realized to further exhibit its synthetic utility.

Substrate Self-Assisted Secondary Bond Activation of Allylic Alcohol in a Tsuji-Trost Reaction Revealed by NMR Methods.

The first experimental evidence for the palladium-catalyzed secondary bond activation of allylic alcohols in a Tsuji-Trost reaction was provided by NMR methods, such as variable-temperature H NMR, diffusion-ordered spectroscopy (DOSY), Job's method, H NMR titration, and nuclear Overhauser enhancement spectroscopy (NOESY). The experimental results revealed that the substrate self-assisted activation of allylic alcohols is probably performed via a 1:1 binding six-membered-ring complex, which are formed by the formation of the secondary bonds, the hydrogen bond and P···O noncovalent bond between allylic alcohol and phosphonium ylide.

KSO-Mediated Selective Trifluoromethylacylation and Trifluoromethylarylation of Alkenes under Transition-Metal-Free Conditions: Synthetic Scope and Mechanistic Studies.

A practical and efficient method for selective intramolecular radical trifluoromethylacylation and -arylation of alkenes with inexpensive CFSONa and KSO in aqueous media has been developed, respectively, affording the highly chemoselective synthesis of CF-functionalized chroman-4-ones and chromanes in satisfactory yields. Control experiments and DFT calculations indicate that the CFSONa/KSO system is capable of trifluoromethylating the substrate of alkenes without a transition metal catalyst and the oxidation of CFSONa to ·CF by KSO is involved in the rate-determining step.

Efficient dehydrative alkylation of thiols with alcohols catalyzed by alkyl halides.

Alcohols can be efficiently converted into the useful thioethers by a transition metal- and base-free dehydrative S-alkylation reaction with thiols or disulfides by employing alkyl halides as the effective catalyst. This simple and efficient method is a green and practical way for the preparation of thioethers, as it tolerates a wide range of substrates such as aryl and alkyl thiols, as well as benzylic, allylic, secondary, tertiary, and even the less reactive aliphatic alcohols.

N-Alkylation by Hydrogen Autotransfer Reactions [corrected].

Owing to the importance of amine/amide derivatives in all fields of chemistry, and also the green and environmentally benign features of using alcohols as alkylating reagents, the relatively high atom economic dehydrative N-alkylation reactions of amines/amides with alcohols through hydrogen autotransfer processes have received much attention and have developed rapidly in recent decades. Various efficient homogeneous and heterogeneous transition metal catalysts, nano materials, electrochemical methods, biomimetic methods, asymmetric N-alkylation reactions, aerobic oxidative methods, and even certain transition metal-free, catalyst-free, or autocatalyzed methods, have also been developed in recent years. With a brief introduction to the background and developments in this area of research, this chapter focuses mainly on recent progress and technical and conceptual advances contributing to the development of this research in the last decade.

Palladium-catalyzed stereospecific cross-coupling of enantioenriched allylic alcohols with boronic acids.

In the presence of 2.5 mol% Pd2(dba)3-TMEDA (1 : 4), a range of enantioenriched allylic alcohols smoothly coupled with boronic acids in a highly regioselective fashion with inversion of configuration to afford structurally diverse alkenes in good yields with perfect retention of ee.

Catalytic allylation of stabilized phosphonium ylides with primary allylic amines.

A range of ketone-stabilized phosphonium ylides were allylated with high regioselectivity by primary allylic amines in the presence of 5 mol % Pd(PPh3)4 and 10 mol % B(OH)3, and subsequent one-pot Wittig olefination gave structurally diverse α,β-unsaturated ketones in good to excellent overall yields with excellent E selectivity. The one-pot allylation/olefination reaction was extended to ester- and nitrile-stabilized phosphonium ylides by replacing B(OH)3 with TsOH, and the corresponding α,β-unsaturated esters and nitriles were obtained in moderate overall yields.

Catalytic regioselective synthesis of structurally diverse indene derivatives from N-benzylic sulfonamides and disubstituted alkynes.

An unprecedented protocol has been developed for the regioselective synthesis of structurally diverse indene derivatives from readily accessible N-benzylic sulfonamides and disubstituted alkynes through FeCl(3)-catalyzed cleavage of sp(3) carbon-nitrogen bonds to generate benzyl cation intermediates. In the presence of 10 mol % of FeCl(3), a broad range of N-benzylic sulfonamides smoothly react with internal alkynes, alkynylcarbonyl compounds, alkynyl chalcogenides, or alkynyl halides to afford various functionalized indene derivatives with extremely high regioselectivity.