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.

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 1H NMR, Job plot, and 1H 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 (Na2S2O3·5H2O) 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 Na2S2O3·5H2O is crucial in generating the key thiol intermediates and byproduct NaHSO4, which then catalyzes the dehydrative substitution of alcohols with thiols to afford thioethers.

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 1H NMR, diffusion-ordered spectroscopy (DOSY), Job's method, 1H 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.

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-1H-pyrazole, and chlorination and bromination of 1,3-dicarbonyl compounds are realized to further exhibit its synthetic utility.

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.

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. Of these, 49 patients (45 males) underwent endovascular aortic repair (EVAR) with a mean age of (49.69 ± 10.21) years (30-75 years), and 13 patients (11 males) underwent thoracoabdominal aortic replacement (TAAR) with a mean age of (41.00 ± 11.18) years (23-66 years). In this study, we retrospectively analyzed the recorded data of 62 patients. In addition, we summarized and analyzed their Computed Tomographic Angiography (CTA) results and perioperative complications. Outcome: In the EVAR group, 47 patients (95.92%) were successfully implanted with overlapping stents, and 2 patients died in the perioperative period. Postoperative complications included cerebral infarction (4.08%), acute renal insufficiency (30.61%), pulmonary insufficiency and need for ventilator (6.12%), poor wound healing (2.04%), postoperative reoperation (16.33%), and lower limb ischemia (2.04%). In the TAAR group, 12 patients (92.31%) were successfully revascularized and 1 patient died in the perioperative period. Postoperative complications included cerebral infarction (7.69%), acute kidney injury (46.15%), pulmonary insufficiency and need for ventilator (15.38%), poor wound healing (30.77%) and postoperative reoperation (15.38%). Conclusion: According to the results of the study, compared with TAAR, EVAR was less invasive, faster recovery, and offered a better choice for some high-risk and high-age patients with comorbid underlying diseases. However, the rate of revascularization was higher after EVAR than TAAR due to vascular lesions. Compared with the use of ascending aortic replacement + hemi-aortic arch replacement for acute type A aortic dissection in many countries and regions, the use of ascending aortic replacement + aortic arch replacement + elephant trunk stent is more traumatic in China, but facilitates reoperation. For young patients, the choice of treatment should be individualized combining vascular lesions and long-term quality of life.

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,ß-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,ß-unsaturated esters and nitriles were obtained in moderate overall yields.

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. Hybrid surgery for aortic disease involving the visceral arteries, consisting of visceral aortic debranching with retrograde revascularization of the celiac trunk and renal arteries and using stent grafts, has been previously described and may be considered particularly appealing in high-risk patients. This study retrospectively analyzed recorded data of patients and contrasted the outcomes with those of a similar group of patients who underwent conventional open repair surgery. Methods: Between 2019 and 2022, 72 patients (52 men) with an average age of 61.57 ± 8.66 years (range, 36-79 years) underwent one-stage debranching abdominal aortic hybrid surgery. These patients, the hybrid group, underwent preoperative Computed Tomographic Angiography (CTA) and had been diagnosed with aortic disease (aneurysm or dissection) involving the visceral arteries and were at high risk for open repair. The criteria used to define these patients as high-risk group who are in the need of hybrid treatment were American Society of Anesthesiologists (ASA) class 3 or 4. In all cases, we accomplished total visceral aortic debranching through a previous visceral artery retrograde revascularization with synthetic grafts (customized Y or four-bifurcated grafts), and aortic endovascular repair with one of two different commercially produced stent grafts (Medtronic® and Lifetech®). In some cases, we chose to connect the renal artery to the artificial vessel with a stent graft (Viabahn) and partly or totally anastomosed. We analyzed the results and compared the outcomes of the hybrid group with those of a similar group of 46 patients (36 men) with an average age 54.15 ± 12.12 years (range, 32-76). These 46 patients, the conventional open group, were selected for having had thoracoabdominal aortic replacement between 2019 and 2022. Results: In the hybrid group, 72 visceral bypasses were completed, and endovascular repair was successful in all cases. No intraoperative deaths occurred. Perioperative mortality was 2.78%, and perioperative morbidity was 9.72% (renal insufficiency in 1, unilateral renal infarction in 5, Intestinal ischemia in 1). At 1-month postoperative CTA showed 2 endoleaks, one of which was intervened. At follow-up, there were unplanned reoperation rate of 4.29% and 5 (7.14%) deaths. The remaining patients' grafts were patent at postoperative CTA and no endoleak or stent graft migration had occurred. In the conventional open group, 1 died intraoperatively, 4 died perioperatively, perioperative mortality was 10.87% and complications were respiratory failure in 5, intestinal paralysis/necrosis in 4, renal insufficiency in 17, and paraplegia in 2. At follow-up, 5 (12.20%) patients presented with synthetic grafts hematoma 4 (9.76%) patient died, and 6 (14.63%) patients required unplanned reoperation intervention. Conclusion: Hybrid surgery is technically feasible in selected cases. For aortic diseases involving the visceral arteries, the application of hybrid abdominal aorta debranching can simplify the operation process, decrease the risks of mortality and morbidity in high-risk and high-age populations and decrease the incidence of various complications while achieving ideal early clinical efficacy. However, a larger series is required for valid statistical comparisons, and longer follow-ups are necessary to evaluate the long-term efficacy of hybrid surgery.

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. CASE SUMMARY: We present a case report of a 50-year-old male with KD in the right aortic arch with aberrant left subclavian artery. We conducted a total endovascular repair procedure, which is innovative and will spread more light in the medical world. Our patient has no past medical history and is a non-smoker and non-alcoholic. Patient presented with shortness of breath, chest pain and dizziness for six months. Blood tests were done and computerized tomography (CT) angiogram of the chest confirmed the diagnosis, illustrating showed a 3.9 cm KD. On Day 1, the CT angiogram showed mild dilatation of the thoracic aorta, adjacent esophagus, trachea was compressed and displaced. Surgery was planned as the treatment modality. Carotid-Subclavian artery bypass and endovascular aortic repair was conducted. We used prolene 5-0 C1 sutures to precisely anastomose a 6-mm Dacron graft to the left subclavian artery. Haemostasis was secured and wounds were closed. Protamine was administered and patient was shifted to intensive care unit. Post-operative, patient responded favorably and was discharged. Regular follow-up is done. CONCLUSION: The procedure we performed is novel. This will help the cardio-thoracic surgeons a better insight about the full procedures we conducted, thereby bringing more light and better treatment options in managing KD with aberrant subclavian artery.

CO2-Driven reversible transfer of amine-functionalized ZIF-90 between organic and aqueous phases.

Phase transfer of metal-organic frameworks is highly desired in many areas, which remains a challenge. Herein, we present for the first time a CO2-driven reversible transfer of amine-functionalized ZIF-90 between organics and water. A mechanistic study showed that the switching is ascribed to the reversible generation of hydrophilic ammonium salts from the reaction of CO2 with the amines on ZIF-90. This unique system has been used for the coupling of trans-esterification reactions, product separation and component recycling for green sustainable processes. This work opens up a new avenue for performing reactions effectively with an easy separation process.

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.

K2S2O8-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 CF3SO2Na and K2S2O8 in aqueous media has been developed, respectively, affording the highly chemoselective synthesis of CF3-functionalized chroman-4-ones and chromanes in satisfactory yields. Control experiments and DFT calculations indicate that the CF3SO2Na/K2S2O8 system is capable of trifluoromethylating the substrate of alkenes without a transition metal catalyst and the oxidation of CF3SO2Na to ·CF3 by K2S2O8 is involved in the rate-determining step.

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. In addition to mainstream research on homogeneous and heterogeneous transition metal-catalyzed reactions, possible mechanistic routes for hydrogen transfer and alcohol activation, which are key processes in N-alkylation reactions but seldom discussed in the past, the recent reports on computational mechanistic studies of the N-alkylation reactions, and the newly emerged N-alkylation methods based on novel alcohol activation protocols such as air-promoted reactions and transition metal-free methods, are also reviewed in this chapter. Problems and bottlenecks that remained to be solved in the field, and promising new research that deserves greater future attention and effort, are also reviewed and discussed.

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 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.