THE TELESCOPIC APPROACH AS A TOOL FOR GREEN CHEMISTRY. One-pot reactions have become a powerful tool for the development of sustainable protocols in organic synthesis. In particular, the telescoping of multi-step reactions, i.e., the execution of sequential reactions without isolating and purifying intermediates, reduces the number of steps while preventing waste generation. Additionally, the processes become more sustainable through time, reagents/solvents, energy and cost savings. Therefore, the aim of this work is to summarize and discuss representative one-pot telescoped strategies involving heterocyclic construction, cross-coupling and continuous-flow reactions.

A facile and efficient method for esterification and amidation of carboxylic acids under neutral conditions has been developed. Esters and amides can be prepared by reacting a carboxylic acid (1 mmol) with tribromoisocyanuric acid (0.37 mmol) and triphenylphosphine (1 mmol) in dichloromethane at room temperature, followed by addition of an alcohol or an amine, respectively.

Foi desenvolvido um método fácil e eficiente para a conversão de alcoóis em brometos de alquila em meio neutro, utilizando ácido tribromoisocianúrico e trifenilfosfina (razão molar 1,0:0,7:2,0, álcool/ácido tribromoisocianúrico/trifenilfosfina) em diclorometano à temperatura ambiente. Esse método pode ser aplicado para a conversão de alcoóis primários, secundários, benzílicos e alílicos, sendo os brometos correspondentes obtidos em 67-82% de rendimento. Alcoóis terciários não são reativos sob estas condições.

An efficient and facile method has been developed for the conversion of alcohols into alkyl bromides under neutral conditions using tribromoisocyanuric acid and triphenylphosphine (molar ratio 1.0:0.7:2.0, alcohol/tribromoisocyanuric acid/triphenylphosphine) in dichloromethane at room temperature. This method can be applied for the conversion of primary, secondary, benzylic and allylic alcohols, and their corresponding bromides are obtained in 67-82 % yield. Tertiary alcohols do not react under these conditions.

Os ácidos tribromo- e tricloro-isocianúricos reagem com ácidos cinâmicos na presença de NaOH/H2O/Et2O à temperatura ambiente para produzir regiosseletivamente (E)-2-halo-estirenos em 25-95% de rendimento. Estudo sobre o mecanismo da reação utilizando correlações Hammett e cálculos DFT (teoria do funcional da densidade) mostraram que esta reação tem como passo determinante a velocidade da adição eletrofílica de um átomo de cloro à ligação dupla.

Tribromo- and trichloroisocyanuric acids react with cinnamic acids in NaOH/H2O/Et2O at room temperature to produce (E)-2-halostyrenes regioselectively in 25-95% yield. Mechanism studies using Hammett correlations and DFT (density functional theory) calculations have shown that this reaction has as rate determining step the electrophilic addition of chlorine atom to the double bond.

Primary, secondary and tertiary alcohols can be easily distinguished due to their reactivity towards tribromoisocyanuric acid (TBCA). The test is performed by adding TBCA to the alcohol in a test tube heated in a boiling water bath. Orange color develops in the tube containing the primary alcohol, light yellow is observed in the tube containing the secondary alcohol while the tertiary alcohol results in a colorless mixture.

O ácido dicloro-iodo-isocianúrico foi preparado em 93% de rendimento através do aquecimento do ácido tricloro-isocianúrico com 1,05 equiv. mol de iodo. Esse novo reagente se mostrou bastante eficiente para a iodação regiosseletiva de arenos ativados. Os alquenos reagem com o ácido dicloro-iodo-isocianúrico na presença de solventes nucleofílicos oxigenados (água, álcoois, ácido acético) para gerar, respectivamente, iodoidrinas, β-iodoéters e β-iodoacetatos em menos de um minuto de reação e em alto grau de regiosseletividade. Enol-éteres levam à formação regiosseletiva dos iodo-dialquilacetais correspondentes. Os resultados experimentais juntamente com os cálculos por DFT mostraram que, para reações com sistemas insaturados, o ácido dicloro-iodo-isocianúrico é mais reativo do que o ácido triiodo-isocianúrico.

Dichloroiodoisocyanuric acid was prepared in 93% by heating trichloroisocyanuric acid with 1.05 mol equiv. of iodine. This new reagent is very efficient for regioselective electrophilic iodination of activated arenes. Alkenes react with dichloroiodoisocyanuric acid in the presence of oxygenated nucleophiles (water, alcohols, and acetic acid), leading to the corresponding iodohydrins, β-iodoethers and β-iodoacetates with reaction times of less than one minute and with a high degree of regioselectivity. Enol ethers resulted in the regioselective formation of the corresponding iodine-dialkylacetals. Experimental results and DFT calculations showed that dichoroiodoisocyanuric acid is more reactive with unsaturated systems than triiodoisocyanuric acid.

Use of clays as catalyzers in heterogeneous processes has increased significantly given their low cost, safety and commercial availability. However, interconnected political, economic, social, environmental, geological, and chemical aspects should be considered for chemical processes to satisfy sustainable development concepts. This concept requires complex thinking involving different areas of knowledge in dialogue, contrasting with classical thought, which is linear and Cartesian. Thus, this paper discusses the principles of complex thought in the concept of sustainable development exemplified by use of clay as a clean technology in organic synthesis.

Este trabalho avalia a inclusão da problemática do tabagismo no currículo da Faculdade de Ciências Médicas da Santa Casa de São Paulo (FCMSCSP) e investiga o envolvimento de alunos e professores de Medicina e Enfermagem em relação ao assunto. Coordenadores das disciplinas dos dois cursos dessa faculdade foram entrevistados sobre abordagem do tabagismo e engajamento pessoal no assunto. Pedimos que formulassem questões sobre tabagismo discutidas durante o curso. Entrevistamos 120 alunos do curso médico e 80 do curso de Enfermagem, aplicando-lhes as questões formuladas. Alunos dos dois últimos períodos dos dois cursos responderam, ainda, a perguntas sobre o trato com pacientes. Os resultados apontam suficiente carga horária destinada ao assunto, havendo disciplinas com aulas específicas sobre tabagismo e outras que abordam o assunto num contexto mais amplo. Os alunos tiveram êxito nos questionários, ficando claro que o assunto é abordado com competência. A maioria dos professores de Medicina tem contato com pacientes, mas um pequeno número questiona sobre o tabagismo, porém não orienta seus pacientes a abandoná-lo. Uma minoria dos professores de Enfermagem tem contato com pacientes, mas, quando tem, questiona e orienta seus pacientes sobre o assunto. Alunos dos últimos períodos dos dois cursos, na maioria das vezes, questionam sobre tabagismo, porém são inseguros quanto ao seguimento das orientações. Concluímos que os alunos formandos estão preparados para enfrentar os problemas referentes ao tabagismo, mas os professores estão pouco envolvidos.

This study analyzes the inclusion of tobacco use in the curriculum of the São Paulo Mercy Hospital School of Medicine (FCMSCSP) and studies the involvement by medical and nursing students and faculty in this topic. Course coordinators from the two courses were interviewed on the approach to smoking and personal involvement in the issue. We asked them to draft questions on smoking as discussed during their courses. We interviewed 120 medical students and 80 nursing students. Patients from the last two semesters in the two courses were also asked about patient treatment. The findings point to a sufficient number of class hours on the subject, with some disciplines including specific classes on smoking and others approaching it within a broader context. The students answered the questionnaires successfully, demonstrating clearly that the topic is approached competently. Most of the medical school professors have direct contact with patients, but few ask about the smoking habit or orient their patients to quit. Few nursing professors have contact with patients, but when they do they provide patients with appropriate orientation. Most students from the last two semesters usually ask patients about smoking, but they are insecure about how closely their orientation is followed. We conclude that by the end of their undergraduate training students are ready to deal with smoking-related problems, but professors show limited involvement in the issue.

O ácido triiodo-isocianúrico (TICA) foi preparado em 90% de rendimento a partir do aquecimento do ácido tricloro-isocianúrico com iodo em um tubo selado. A reação do TICA com arenos ativados em acetonitrila gera regiosseletivamente os respectivos iodo-arenos em 73-93% de rendimento isolado. Anilina e fenol também são monoiodados seletivamente usando MeOH (53%) e CH2Cl2 (88%) como solventes, respectivamente.

Triiodoisocyanuric acid (TICA) was prepared in 90% yield by heating trichloroisocyanuric acid with iodine in a sealed tube. The reaction of TICA with activated arenes in acetonitrile led to an efficient and highly regioselective formation of the corresponding iodoarenes, in 73-93% isolated yield. Aniline and phenol are monoiodinated regioselectively using MeOH (53%) and CH2Cl2 (88%) as solvents, respectively.

The chlorination of activated aromatic rings is efficiently achieved under mild conditions by reaction of aromatic compounds with trichloroisocyanuric acid in acetonitrile, at room temperature, leading to products in 60-95% isolated yields and good regioselectivity.

Horse radish peroxidase (HRP) from Armoracia rusticana catalyses the oxidation of (R)-limonene into the oxidized derivatives carveol and carvone. This study compares the direct addition (DA) of hydrogen peroxide with its continuous electrogeneration (EG) during the enzymatic oxidation of (R)-limonene. Reaction mixtures containing HRP, (R)-limonene as substrate, and hydrogen peroxide, added directly or electrogenerated, in 100 mM sodium-potassium phosphate buffer pH 7.0, at 25ºC were studied. Two electrochemical systems for the hydrogen peroxide electrogeneration were evaluated, both containing as auxiliary electrode (AE) a platinum wire and saturated calomel electrode (SCE) as reference. Reticulated vitreous carbon foam (RVCF) and an electrolytic copper web (CW) were evaluated as working electrodes (WE). Results were compared in terms of hydrogen peroxide electrogeneration, (R)-limonene residual concentration or conversion and product selectivity. Best results in terms of maximum H2O2 concentration (1.2 mM) were obtained using the CW electrode at -620 mV SCE, and continuous aeration. Use of the EG system under optimized conditions, which included the use of acetone (30% v/v) as a cosolvent in a 3 hrs enzymatic reaction, lead to a 45% conversion of (R)-limonene into carveol and carvone (2:1). In comparison to the results obtained with DA, the use of EG also improved the half-life of the enzyme.

A reação de alquenos com ácidos trialo-isocianúricos / NaX em acetona aquosa produz os dialo-alcanos vicinais em rendimentos de moderados a excelentes

The reaction of alkenes with easily handled trihaloisocyanuric acids / NaX in aqueous acetone produces the corresponding vicinal dihaloalkanes in moderate to excellent yields.

A reação de alquenos com o ácido tricloro-isocianúrico ou N-bromo-sacarina ou I2 / Fe2(SO4)3 na presença de DMF, seguida de tratamento em meio aquoso, leva à formação dos respectivos beta-halo-formatos com alta regio- e estereosseletividade.

The reaction of alkenes with trichloroisocyanuric acid or N-bromosaccharin or I2 / Fe2(SO4)3 in the presence of DMF followed by aqueous work-up led to the corresponding beta-haloformate in high regio- and stereoselectivity.

A argila comercial brasileira Bentonit Brasgel® foi caracterizada por análises química e textural, DRX e RMN no estado sólido de 27Al and 29Si, que indicaram a presença de quartzo-alfa e esmectita como argilo-minerais. Essa argila se mostrou um catalisador eficiente para a conversão de alquenos nos respectivos epóxidos através da reação com iodo/água seguida de adição de KOH em hexano in situ (80-91 %). Resultados similares foram obtidos usando-se Bentonit Brasgel™ intercalada com Ag(I).

The commercial Brazilian clay Bentonit Brasgel™ was characterized by chemical and textural analyses, XRD, and 27Al and 29Si MAS-NMR, that indicated the presence of alpha-quartz and smectite as clay-minerals. This natural clay proved to be an efficient catalyst for the conversion of alkenes into epoxides by the reaction with iodine/water followed by in situ addition of KOH in hexane (80-91 % yield). Similar results were obtained with Bentonit Brasgel™ intercalated with Ag(I).