Perfluoroalkylation of Triarylamines by EDA Complexes and Ulterior Sensitized [6π]-Electrocyclization to Perfluoroalkylated Endo-Carbazoles. Mechanistic and Photophysical Studies.

Blue LEDs-irradiation of a mixture of N,N,N',N'-tetramethylethylenediamine (TMEDA) and perfluoroalkyl iodides (RF-I) - Electron Donor Acceptor (EDA)-complex - in the presence of triphenylamines (TPAs) in an aqueous solvent mixture afforded mono-perfluoroalkylated triphenylamines (RF-TPA) in good yields. These RF-TPA were further subjected to acetone-sensitized [6π]-electrocyclization at 315 nm-irradiation affording exclusively perfluoroalkylated endo-carbazole derivatives (RF-CBz) in quantitative yields. Mechanistic studies and photophysical properties of products are studied.

Photocatalytic Perfluoroalkylation of Disulfides and Diselenides. Syntheses of Perfluoroalkyl Thio- and Seleno-ethers.

The synthesis of alkyl(aryl)-fluoroalkyl sulfanyl [R(Ar)-S-RF] and aryl-fluoroalkyl selenolyl (Ar-Se-RF) ethers through visible-light photocatalysis has been successfully carried out. This process involves disulfides, and diselenides [R(Ar)-X-X-R(Ar), where X = S or Se], and fluoroalkyl iodides (RF-I) in the presence of a base as an additive under photocatalysis. The photocatalyst Eosin Y and green light-emitting diodes are utilized for irradiation of R(Ar)-S-RF and Ar-Se-RF syntheses. Our method integrates low-energy visible-light photocatalysis, commercially available perfluoroalkylating reagents (RF-I), and easily obtainable disulfides and diselenides as starting materials. Mechanistic studies and a detailed synthetic procedure for (Ar)-S-RF on a large scale are presented.

Radical Reactions in Organic Synthesis: Exploring in-, on-, and with-Water Methods.

Radical reactions in water or aqueous media are important for organic synthesis, realizing high-yielding processes under non-toxic and environmentally friendly conditions. This overview includes (i) a general introduction to organic chemistry in water and aqueous media, (ii) synthetic approaches in, on, and with water as well as in heterogeneous phases, (iii) reactions of carbon-centered radicals with water (or deuterium oxide) activated through coordination with various Lewis acids, (iv) photocatalysis in water and aqueous media, and (v) synthetic applications bioinspired by naturally occurring processes. A wide range of chemical processes and synthetic strategies under different experimental conditions have been reviewed that lead to important functional group translocation and transformation reactions, leading to the preparation of complex molecules. These results reveal how water as a solvent/medium/reagent in radical chemistry has matured over the last two decades, with further discoveries anticipated in the near future.

Long-Term Opioid Therapy Among Patients With Systemic Lupus Erythematosus in the Community: A Lupus Midwest Network (LUMEN) Study.

OBJECTIVE: There is little information about the epidemiology and factors associated with opioid therapy in systemic lupus erythematosus (SLE). We aimed to assess the prevalence of opioid therapy and explore factors associated with long-term opioid therapy (LTOT) in patients with SLE. METHODS: Patients with SLE were matched with controls without SLE in a population-based cohort on January 1, 2015. We captured demographics, manifestations of SLE, comorbidities (ie, fibromyalgia, mood disorders, osteoarthritis, chronic low back pain [CLBP], chronic kidney disease (CKD), avascular necrosis, osteoporosis, fragility fractures, and cancer), and the Area Deprivation Index (ADI). Opioid prescription data were used to assess the prevalence of LTOT, defined as contiguous prescriptions (gaps of < 30 days between prescriptions) and receiving opioid therapy for ≥ 90 days or ≥ 10 prescriptions before the index date. RESULTS: A total of 465 patients with SLE and 465 controls without SLE were included. In total, 13% of patients with SLE and 3% of controls without SLE were receiving opioid therapy (P < 0.001), and 11% of patients with SLE were on LTOT vs 1% of controls without SLE. Among patients with SLE, acute pericarditis (odds ratio [OR] 3.92, 95% CI 1.78-8.66), fibromyalgia (OR 7.78, 95% CI 3.89-15.55), fragility fractures (OR 3.72, 95% CI 1.25-11.07), CLBP (OR 4.00, 95% CI 2.13-7.51), and mood disorders (OR 2.76, 95% CI 1.47-5.16) were associated with LTOT. We did not find an association between opioid therapy and ADI. CONCLUSION: Patients with SLE are more likely to receive LTOT than controls. Among patients with SLE, LTOT was associated with pericarditis and several comorbidities. However, LTOT was not associated with CKD despite the limited pain control options among these patients.

Health Care Utilization in Systemic Lupus Erythematosus in the Community: The Lupus Midwest Network.

OBJECTIVE: The aim of this study was to determine inpatient health care utilization in an incident cohort of patients with systemic lupus erythematosus (SLE) compared with the general population. METHODS: This was a population-based cohort study in the upper Midwest, United States. We included patients fulfilling the European League Against Rheumatism/American College of Rheumatology SLE classification criteria between 1995 and 2018. They were 1:1 age-, sex-, county-matched with individuals without SLE. All hospital admissions and emergency department (ED) visits were electronically retrieved for 1995-2020. Rates for hospital admission, length of stay, readmission, ED visits, and discharge destination were compared between groups. RESULTS: Three hundred forty-one patients with SLE and 341 comparators without SLE were included (mean age, 48.6 years at diagnosis; 79.2% female). Rates of hospitalization for patients with SLE and comparators were 29.8 and 9.9 per 100 person-years, respectively. These differences were present across sexes and age groups. Hospitalization rates were higher in patients with SLE after diagnosis and remained higher than comparators for the first 15 years of the disease. Patients with SLE were more likely than comparators to visit the ED (hazard ratio, 2.71; 95% confidence interval, 2.05-3.59). Readmission rates (32% vs. 21%, p = 0.017) were higher in patients with SLE. Length of stay and discharge destination were similar between both groups. CONCLUSION: Patients with SLE were more likely to be hospitalized and to visit the ED than individuals without SLE, highlighting important inpatient care needs. Increased hospitalization rates were observed in both male and female patients and all age groups.

Trifluoromethoxylation Reactions of (Hetero) arenes, Olefinic Systems and Aliphatic Saturated Substrates.

Direct fluoroalkoxylation reactions of (hetero)arenes, carbon-carbon multiple bonds, and substitution reactions at Csp3 carbon centers by CF3 O, CHF2 O, and (CF3 )2 CFO groups are discussed. Emphasis on thermal radical, electron transfer, photocatalytic, electrochemical and redox-neutral radical methods are placed to accomplish fluoroalkoxylation reactions. All these methods employ either radical fluoroalkoxylating reagents or some nucleophilic trifluoromethoxylating sources of CF3 O. A summary of all these methods is provided in Table 2.

Rural Patient Experiences of Accessing Care for Chronic Conditions: A Systematic Review and Thematic Synthesis of Qualitative Studies.

PURPOSE: Access to health care is a long-standing concern for rural patients; however, administrative measures fail to capture the subjective patient experience of accessing health care. The purpose of this review was to synthesize the qualitative literature on patient and caregiver experiences of accessing health care services for chronic disease management among US residents of rural areas. METHODS: We searched Embase, MEDLINE, PsycInfo, CINAHL, and Scopus to identify qualitative studies published during 2010-2019. A thematic synthesis approach was used to analyze findings from included studies. RESULTS: A total of 62 studies involving 1,354 unique participants were included. The largest share of studies (24.2%) was focused on the experience of patients with cancer, followed by behavioral health (16.1%), HIV and AIDS (14.5%), and diabetes (12.9%). We identified 4 primary analytic themes of barriers and facilitators associated with the experience of accessing health care services for chronic disease management in rural areas: (1) navigating the rural environment, (2) navigating the health care system, (3) financing chronic disease management, and (4) rural life (ie, common elements of a distinct "rural" way of thinking and behaving). CONCLUSIONS: In this comprehensive review, we found that important cultural, structural, and individual factors influenced the rural patient's experience of health care access and use, including barriers and facilitators posed by geographic and built environments, and distinct rural mores. Our findings can inform policies and programs that both facilitate structural aspects of access and include culturally appropriate interventions.VISUAL ABSTRACT.

Rose Bengal-photocatalyzed perfluorohexylation reactions of organic substrates in water. Applications to late-stage syntheses.

The Rose Bengal-photocatalyzed perfluorohexylation of olefins, alkynes, and electron-rich aromatic compounds in water was achieved employing perfluorohexyl iodide as fluoroalkyl source and TMEDA as sacrificial donor under green LED irradiation. Alkenes and alkynes rendered products derived from the atom transfer radical addition (ATRA) pathway, and in the case of alkynes, exclusively as E-stereoisomers. These are the first examples of photocatalyzed ATRA reactions carried out excursively in water alone. The reactions of aromatic compounds under the current protocol in water present the advantage of employing a perfluoroalkyl iodide (C6F13-I) as source of perfluorohexyl radicals. Examples of photocatalytic late-stage incorporations of fluoroalkyl moieties into two commercial drugs of widespread use are reported.

Visible light-catalyzed fluoroalkylation reactions of free aniline derivatives.

The electron-rich nature of aminoaromatic compounds and the electrophilic character of fluoroalkyl RF radicals allow for a special match in substitution reactions. We herein present visible light photocatalyzed fluoroalkylation reactions of aniline derivatives, with a study of the reaction mechanisms. The examples evaluated make use of different photocatalysts, such as polypyridyl complexes of Ir or Ru transition metals, organic dyes such as Rose Bengal, phthalocyanine-metal organocatalysts, or visible-light activated complexes. Different visible light sources that span from the blue region of the electromagnetic spectrum to low power red light irradiation sources deliver the excited photocatalysts that ensue into the production of fluoroalkyl RF radicals. In turn, many sources of RF radicals can be employed, such as fluoroalkyl halides, Togni's reagents, Umemoto's reagent, etc. All these protocol variants demonstrate the expansion of the methodology and the versatility of photocatalytic techniques applied to a special family of organic compounds such as aminoaromatic substrates, which has been studied by different groups. Contributions from our own laboratory will be given.

Biomimetic Ketone Reduction by Disulfide Radical Anion.

The conversion of ribonucleosides to 2'-deoxyribonucleosides is catalyzed by ribonucleoside reductase enzymes in nature. One of the key steps in this complex radical mechanism is the reduction of the 3'-ketodeoxynucleotide by a pair of cysteine residues, providing the electrons via a disulfide radical anion (RSSR•-) in the active site of the enzyme. In the present study, the bioinspired conversion of ketones to corresponding alcohols was achieved by the intermediacy of disulfide radical anion of cysteine (CysSSCys)•- in water. High concentration of cysteine and pH 10.6 are necessary for high-yielding reactions. The photoinitiated radical chain reaction includes the one-electron reduction of carbonyl moiety by disulfide radical anion, protonation of the resulting ketyl radical anion by water, and H-atom abstraction from CysSH. The (CysSSCys)•- transient species generated by ionizing radiation in aqueous solutions allowed the measurement of kinetic data with ketones by pulse radiolysis. By measuring the rate of the decay of (CysSSCys)•- at λmax = 420 nm at various concentrations of ketones, we found the rate constants of three cyclic ketones to be in the range of 104-105 M-1s-1 at ~22 °C.

New Visible-Light-Triggered Photocatalytic Trifluoromethylation Reactions of Carbon-Carbon Multiple Bonds and (Hetero)Aromatic Compounds.

Visible-light-photocatalyzed methods employed in synthetic transformations present attractive properties such as environmentally friendly, safety, availability and excellent functional group tolerance. In this regard, research on the visible-light photocatalytic incorporation of the trifluoromethyl CF3 moiety into organic substrates, in particular, has contributed to a clear evolution of the field of photocatalysis. Although this particular area is constantly evolving and has been reviewed, the last five years have experienced an outburst of seminal and significant photocatalytic trifluoromethylation examples that are leading the way and opening new synthetic avenues. Recent review articles on Ru- and Ir-based photocatalytic trifluoromethylation reactions have borne witness of this evolution. Although this account will show the new Ru- and Ir-based photocatalytic trifluoromethylations, Sections 2 and 3 will also illustrate other photocatalytic systems, such as organic dyes, organic semiconductors and newly-developed all-organic photocatalysts. All the known and reviewed strategies for photocatalytic trifluoromethylation reactions of olefins and (hetero)aromatic compounds will not be discussed but will be summarized in two figures (Figures 4 and 5), and new examples (2015-present) will be presented and discussed.

Radical fluoroalkylation reactions of (hetero)arenes and sulfides under red light photocatalysis.

Fluoroalkylation reactions of (hetero)aromatics have been accomplished through the low-power illumination from red LEDs (λmax = 635 nm) of commercially available perfluoroalkyl iodides RF-I and phthalocyanine zinc salt as photocatalyst in MeCN : DMF solvent mixture. This methodology has been extended to the perfluorobutylation of sulfides. As far as we are concerned, this is the first report on a perfluoroalkylation reaction of (hetero)aromatics and sulfides under red-light photocatalysis.

Photocatalytic Difluoromethylation Reactions of Aromatic Compounds and Aliphatic Multiple C-C Bonds.

Among the realm of visible light photocatalytic transformations, late-stage difluoromethylation reactions (introduction of difluoromethyl groups in the last stages of synthetic protocols) have played relevant roles as the CF2X group substitutions exert positive impacts on the physical properties of organic compounds including solubility, metabolic stability, and lipophilicity, which are tenets of considerable importance in pharmaceutical, agrochemical, and materials science. Visible-light-photocatalyzed difluoromethylation reactions are shown to be accomplished on (hetero)aromatic and carbon-carbon unsaturated aliphatic substrates under mild and environmentally benign conditions.

Converging Fate of the Oxidation and Reduction of 8-Thioguanosine.

Thione-containing nucleobases have attracted the attention of the scientific community for their application in oncology, virology, and transplantology. The detailed understanding of the reactivity of the purine derivative 8-thioguanosine (8-TG) with reactive oxygen species (ROS) and free radicals is crucial for its biological relevance. An extensive investigation on the fate of 8-TG under both reductive and oxidative conditions is here reported, and it was tested by employing steady-state photooxidation, laser flash photolysis, as well as γ-radiolysis in aqueous solutions. The characterization of the 8-TG T1 excited state by laser flash photolysis and the photooxidation experiments confirmed that singlet oxygen is a crucial intermediate in the formation of the unexpected reduced product guanosine, without the formation of the usual oxygenated sulfinic or sulfonic acids. Furthermore, a thorough screening of different radiolytic conditions upon γ-radiation afforded the reduced product. These results were rationalized by performing control experiments in the predominant presence of each reactive species formed by radiolysis of water, and the mechanistic pathway scenario was postulated on these bases.

New Insights into the Reaction Paths of Hydroxyl Radicals with Purine Moieties in DNA and Double-Stranded Oligodeoxynucleotides.

The reaction of hydroxyl radical (HO•) with DNA produces many primary reactive species and many lesions as final products. In this study, we have examined the optical spectra of intermediate species derived from the reaction of HO• with a variety of single- and double-stranded oligodeoxynucleotides and ct-DNA in the range of 1 µs to 1 ms by pulse radiolysis using an Intensified Charged Coupled Device (ICCD) camera. Moreover, we applied our published analytical protocol based on an LC-MS/MS system with isotopomeric internal standards to enable accurate and precise measurements of purine lesion formation. In particular, the simultaneous measurement of the four purine 5',8-cyclo-2'-deoxynucleosides (cPu) and two 8-oxo-7,8-dihydro-2'-deoxypurine (8-oxo-Pu) was obtained upon reaction of genetic material with HO• radicals generated either by γ-radiolysis or Fenton-type reactions. Our results contributed to the debate in the literature regarding absolute level of lesions, method of HO• radical generation, 5'R/5'S diastereomeric ratio in cPu, and relative abundance between cPu and 8-oxo-Pu.

Organic dye-photocatalyzed fluoroalkylation of heteroarene-N-oxide derivatives.

The first direct CHet-H perfluoroalkylation reaction of heteroaromatic-N-oxides has been achieved through a visible light-photocatalyzed reaction in the presence of commercially available perfluoroalkyl iodides RF-I and base in DMF as solvent and Rose Bengal as organic photocatalyst. The reactions proceed in the absence of transition metals and can be scaled up. Through an acid-catalyzed transformation of the perfluoroalkylated-N-oxides thus obtained, the first direct syntheses of 2-(perfluoroalkyl)benzo[f][1,3]oxazepines are achieved. De-oxygenation of the resulting perfluoroalkylated heteroaromatic-N-oxides leads to high yielding and regioselective radical perfluoroalkylation protocols of heteroaromatic compounds. To the best of our knowledge, this is the first report on a direct method for perfluoroalkylation of pyridine-, quinoline-, and diazine-N-oxide derivatives.

Difluoromethylation Reactions of Organic Compounds.

The relevance of the -CF2 H moiety has attracted considerable attention from organic synthetic and medicinal chemistry communities, because this group can act as a more lipophilic isostere of the carbinol, thiol, hydroxamic acid, or amide groups. Being weakly acidic, the CF2 H moiety can establish hydrogen-bonding interactions to improve the binding selectivity of biologically active compounds. Therefore, the hydroxyl, amino, and thio substituents of lead structures are routinely replaced by a CF2 H motif in drug discovery, with great benefits in the pharmacological activity of drugs and drug candidates and agrochemicals. Consequently, the late-stage introduction of CF2 H is a sought-after strategy in designing bioactive compounds. Secondly, but nonetheless relevant and meaningful, is the study of synthetic pathways to introduce a CF2 -Y moiety (Y≠H, F) into organic substrates because compounds that contain a CF2 -Y functionality have also found vast applications in medicinal chemistry and in other areas, such as that of fungicides, insecticides, etc., and thus, this functionality deserves special attention. Although emphasis is made on difluoromethylation strategies to functionalize different families of organic compounds, three main methodological protocols will be presented in this review article for the late-stage introduction of a CF2 H or CF2 Y moieties into organic substrates: i) a metal-photoredox catalysis; ii) through transition metal-catalyzed thermal protocols; and iii) from transition-metal-free strategies.

Late stage trifluoromethylthiolation strategies for organic compounds.

Substitution by the CF3S group allows for an increase in lipophilicity and electron-withdrawing properties along with an improvement in the bioavailability of medicinal targets; consequently, the late stage introduction of CF3S moieties into medicinal scaffolds is a sought-after strategy in synthetic organic chemistry. Different newly-developed electrophilic and nucleophilic reagents are used to effect the trifluoromethylthiolation of (hetero)aromatic compounds, aliphatic compounds (alkyl, alkenyl, alkynyl substrates), the trifluoromethylthiolation at the α- and ß-carbonyl positions, and heteroatoms (N- and S-). Such reactions can involve homolytic substitutions, or functional-group substitutions (ipso). Addition reactions of electrophilic reagents to double and triple bonds followed by ring-cyclizations will be shown to yield relevant CF3S-substituted heteroaromatic compounds with relevant pharmacological action.

Photocatalytic fluoroalkylation reactions of organic compounds.

Photocatalytic methods for fluoroalkyl-radical generation provide more convenient alternatives to the classical perfluoroalkyl-radical (Rf) production through chemical initiators, such as azo or peroxide compounds or the employment of transition metals through a thermal electron transfer (ET) initiation process. The mild photocatalytic reaction conditions tolerate a variety of functional groups and, thus, are handy to the late-stage modification of bioactive molecules. Transition metal-photocatalytic reactions for Rf radical generation profit from the redox properties of coordinatively saturated Ru or Ir organocomplexes to act as both electron donor and reductive species, thus allowing for the utilization of electron accepting and donating fluoroalkylating agents for Rf radical production. On the other hand, laboratory-available and inexpensive photoorgano catalysts (POC), in the absence of transition metals, can also act as electron exchange species upon excitation, resulting in ET reactions that produce Rf radicals. In this work, a critical account of transition metal and transition metal-free Rf radical production will be described with photoorgano catalysts, studying classical examples and the most recent investigations in the field.

Bleomycin-induced trans lipid formation in cell membranes and in liposome models.

Cell cultures of NTera-2 cells incubated with bleomycin and liposomes as biomimetic models of cell membranes were used for examining some novel aspects of drug-metal induced reactivity with unsaturated lipids under oxidative conditions. In cell cultures, bleomycin was found for the first time to cause the formation of trans fatty acids. The chemical basis of this transformation was ascertained by liposome experiments, using bleomycin-iron complexes in the presence of thiol as a reducing agent that by incubation at 37 °C gave rise to the thiyl radical-catalysed double bond isomerisation of membrane phospholipids. The effect of oxygen and reagent concentrations on the reaction outcome was studied. An interesting scenario of free radical reactivity is proposed, which can be relevant for understanding the role of membrane lipids in antitumoral treatments and drug carrier interaction.