Engaging Isatins in Multicomponent Reactions (MCRs) – Easy Access to Structural Diversity

Multicomponent reactions (MCRs) are a valuable tool in diversity-oriented synthesis. Its application to privileged structures is gaining relevance in the fields of organic and medicinal chemistry. Isatin, due to its unique reactivity, can undergo different MCRs, affording multiple interesting scaffolds, namely oxindole-derivatives (including spirooxindoles, bis-oxindoles and 3,3-disubstituted oxindoles) and even, under certain conditions, ring-opening reactions occur that leads to other heterocyclic compounds. Over the past few years, new methodologies have been described for the application of this important and easily available starting material in MCRs. In this review, we explore these novelties, displaying them according to the structure of the final products obtained

Cromatografia gasosa-espectrometria de massas e derivatização assistida por micro-ondas na identificação de isômeros de glicose: uma prática para o ensino avançado em análise e caracterização de compostos orgânicos

This work reports a practical case based on the use of microwave-assisted derivatization and GC-MS for the analysis of glucose. Using two different methods for derivatization, one reference compound and the calculated dipole moment, all the isomers of glucose were identified. Identification was corroborated for the assignment of structures using the mass spectra. With this work, students are expected to associate different types of information to solve the complex problem of the analysis of glucose

New Halogenated Phenylbacteriochlorins and Their Efficiency in Singlet-Oxygen Sensitization

Halogenated phenylbacteriochlorins are synthesized with high yields in a two-step procedure. They have strong absorbances in the red and are very stable to air and light at room temperature. Flash photolysis measurements show that the triplet states of these bacteriochlorins have 30 μs lifetimes in deaerated toluene, that are quenched with diffusion-controlled rate constants by molecular oxygen. Time-resolved photoacoustic measurements, with nanosecond and nanocalorie resolution, show that these bacteriochlorins sensitize the formation of singlet oxygen with nearly unity quantum yield. However, singlet-oxygen phosphorescence measurements indicate that physical quenching occurs before the singlet-oxygen molecules diffuse into solution, and nearly half of the sensitized singlet states are lost

Tritolylporphyrin dimer as a new potent hydrophobic sensitizer for photodynamic therapy of melanoma

We report the synthesis, photochemical and photophysical properties and preliminary studies on biological effect of a new tritolylporphyrin dimer (T-D). Absorption and emission properties of T-D suggest its possible use in photodynamic therapy. T-D is capable of singlet oxygen production with 0.8 quantum yield. It also has a high photostability. The photodynamic properties of the dimer were examined following the growth of SKMEL 188 (human melanoma) cells irradiated with red light (cut off vs. non-irradiated cells) for an 81 J/cm2 dose. Our results suggest that tritolylporphyrine dimer T-D may be an interesting hydrophobic sensitizer for photodynamic therapy

Predicting Clinical Outcome with Phenotypic Clusters in COVID-19 Pneumonia: An Analysis of 12,066 Hospitalized Patients from the Spanish Registry SEMI-COVID-19

(1) Background: Different clinical presentations in COVID-19 are described to date, from mild to severe cases. This study aims to identify different clinical phenotypes in COVID-19 pneumonia using cluster analysis and to assess the prognostic impact among identified clusters in such patients. (2) Methods: Cluster analysis including 11 phenotypic variables was performed in a large cohort of 12,066 COVID-19 patients, collected and followed-up from 1 March to 31 July 2020, from the nationwide Spanish Society of Internal Medicine (SEMI)-COVID-19 Registry. (3) Results: Of the total of 12,066 patients included in the study, most were males (7052, 58.5%) and Caucasian (10,635, 89.5%), with a mean age at diagnosis of 67 years (standard deviation (SD) 16). The main pre-admission comorbidities were arterial hypertension (6030, 50%), hyperlipidemia (4741, 39.4%) and diabetes mellitus (2309, 19.2%). The average number of days from COVID-19 symptom onset to hospital admission was 6.7 (SD 7). The triad of fever, cough, and dyspnea was present almost uniformly in all 4 clinical phenotypes identified by clustering. Cluster C1 (8737 patients, 72.4%) was the largest, and comprised patients with the triad alone. Cluster C2 (1196 patients, 9.9%) also presented with ageusia and anosmia; cluster C3 (880 patients, 7.3%) also had arthromyalgia, headache, and sore throat; and cluster C4 (1253 patients, 10.4%) also manifested with diarrhea, vomiting, and abdominal pain. Compared to each other, cluster C1 presented the highest in-hospital mortality (24.1% vs. 4.3% vs. 14.7% vs. 18.6%; p 20 bpm, lower PaO2/FiO2 at admission, higher levels of C-reactive protein (CRP) and lactate dehydrogenase (LDH), and the phenotypic cluster as independent factors for in-hospital death. (4) Conclusions: The present study identified 4 phenotypic clusters in patients with COVID-19 pneumonia, which predicted the in-hospital prognosis of clinical outcomes

A biologia educacional e os fundamentos da educação: o caso do Paraná.

Este artigo apresenta um breve histórico da Biologia Educacional no Brasil e discute as principais mudanças que ocorreram na disciplina, nos oitenta anos de existência da UFPR

Mechanochemical in situ generated gas reactant for the solvent-free hydrogenation of porphyrins

The synthesis of chlorins was performed by hydrogenation of porphyrins using diimide generated and consumed under mechanical activation. The reaction conditions achievable under ball milling, absence of solvent and use of hydrazine hydrate as diimide source, allowed the hydrogenation of porphyrins with high conversion, high selectivity, and nearly ideal sustainability scores (atom economy of 97% and E-factor of 0.96)

Modern Methods for the Sustainable Synthesis of Metalloporphyrins

Metalloporphyrins are involved in many and diverse applications that require the preparation of these compounds in an efficient manner, which nowadays, also involves taking into consideration sustainability issues. In this context, we use ball milling mechanochemistry and sonochemistry for the rational development of synthetic strategies for the sustainable preparation of metalloporphyrins. Zinc, copper, cobalt and palladium complexes of hydrophobic porphyrins were obtained in high yields and under mechanical action with a moderate excess of the metal salt, without any solvent or additive. Sonochemistry prove to be a good alternative for the preparation of metal complexes of water-soluble porphyrins in good yields and short reaction times. Both strategies have good sustainability scores, close to the ideal values, which is useful in comparing and helping to choose the more adequate method

Tryptanthrin and Its Derivatives in Drug Discovery: Synthetic Insights

Tryptanthrin is a golden-yellow, naturally occurring alkaloid that can be obtained from multiple sources and through different synthetic methodologies. This tetracyclic compound displays several relevant biological activities. The potential of this tetracyclic alkaloid has been widely explored, and several researchers have focused their attention on expanding the variety of tryptanthrin derivatives by using a range of synthetic strategies. In this short review, we aim to address recent developments in the synthesis of the tryptanthrin core, as well as the development of new strategies employed by synthetic organic chemists to obtain novel tryptanthrin derivatives with potential biological activity, using different tools from the chemists’ toolbox, such as photocatalysis, solvent-free approaches, and multicomponent reactions

The influence of the support on the singlet oxygen quantum yields of porphyrin supported photosensitizers

A halogenated porphyrin was covalently supported on aminoalkylated silica and aminoalkylated Merrifield polymer through a chlorosulfonation reaction. The supported porphyrin was tested for the photoxidation of α-terpinene. The kinetics of photocatalysis were evaluated using 9,10-dimethylanthracene as target and singlet oxygen formation quantum yield was calculated. The influence of the support, silica, Merrifield and other polymers, on the quenching of singlet oxygen were also evaluated