Síntese de novos azobenzotiazóis a partir dos respectivos sintões nitrosos

A presente dissertação reporta a síntese de novos azobenzotiazóis preparados a partir da condensação de 2-nitrosobenzotiazóis com anilinas primárias contendo grupos electrodadores ou electroactratores como substituintes, em diferentes posições. Este novo método tem a vantagem de ser uma abordagem mais ampla para a obtenção de azobenzotiazóis do que método clássico de diazotização, uma vez que permite uma maior diversificação, quer das posições dos substituintes no anel fenílico, quer da sua natureza. Todos os compostos sintetizados são caracterizados por espectrometria de ressonância magnética de protão e carbono, de massa e espectrofotometria de infravermelho e ultravioleta/visível. Discutem-se os resultados obtidos, com respeito ao método de síntese e analisa-se a relação entre a estrutura dos azobenzotiazóis e o respectivo espectro de visível, no que diz respeito à influência dos substituintes no anel benzotiazólico e à dos substituintes no anel fenílico. É igualmente feita uma pequena revisão sobre a síntese de compostos nitrosados e corantes azo, bem como acerca das principais aplicações deste tipo de corantes.This thesis reports the synthesis of novel azobenzothiazole dyes prepared by condensation of 2-nitrosobenzothiazoles with primary anilines bearing electron withdrawing or electron donating groups at several positions. The new method is advantageous due to its wider approach for the preparation of azobenzothiazole dyes over the classic diazotization process since it allows a greater diversification, either of the positions of the substituents on the phenylic ring, or its nature. All synthesized compounds were conveniently characterized by 1 H and 13C nuclear magnetic resonance, mass, infrared and ultraviolet-visible spectrophotometry. The observed results are discussed in respect to its synthetic method, and the relation between the azobenzothiazole structure and its visible spectra is analysed, in regard to the influence of the substituents in the benzothiazole ring and the substituents in the phenylic ring. A short revision about the synthesis of nitroso compounds and azo dyes, as well as about the main applications of this type of dyes, is also made

Gold (I) catalyzed intermolecular cycloadditions of allenes

Gold (I) catalyzed intermolecular cycloadditions of allenes Herein, we describe our efforts in the development of intermolecular Au-catalyzed cycloadditions with allenic scaffolds. In particular, we demonstrate that the use of allenamides, a particularly accessible and versatile type of allenic scaffold, allowed the discovery of highly selective and even enantioselective gold-catalyzed (4 + 2) cycloadditions to 1,3-dienes. We also pursue the development of a gold-catalyzed intermolecular (2 + 2) cycloaddition, which could be eventually achieved using appropriate alkenes and a phosphite-gold catalyst. Finally, a simple and highly versatile cascade cycloaddition between allenamides and carbonyl-tethered alkenes, including several enantioselective examples, is also described. This method enables a straightforward and highly efficient entry to oxa-bridged seven-, eight- and even nine-membered rings. Cicloadiciones intermoleculares de alenos catalizadas por Oro En esta tesis se describe el desarrollo de cicloadiciones intermoleculares catalizadas por oro utilizando sistemas alenicos. En particular, demostramos que el uso de alenamidas, un sistemas alenico especialmente versátil y accesible, ha permitido el descubrimiento de nuevas cicloadiciones (4+2) intemoleculares catalizadas por oro con 1,3-dienos de modo altamente selectivo y incluso enantioselectivo. También se investiga el desarrollo de una cicloadición (2+2) intermolecular catalizada por oro, que se pudo conseguir utilizando alquenos apropiados y un catalizador de fosfito-oro. Por último, se describe una cicloadición en cascada, simple y altamente versátil entre alenamidas y alquenos unidos a un carbonilo, incluyendo varios ejemplos enantioselectivos. Este método permite la obtención fácil y eficiente de anillos de siete, ocho o incluso nueve miembros con un puente de oxigeno

Gold(I)‐Catalyzed Cascade Cycloadditions between Allenamides and Carbonyl‐Tethered Alkenes: An Enantioselective Approach to Oxa‐Bridged Medium‐Sized Carbocycles

This is the peer reviewed version of the following article: Faustino, H. , Alonso, I. , Mascareñas, J. L. and López, F. (2013), Gold(I)‐Catalyzed Cascade Cycloadditions between Allenamides and Carbonyl‐Tethered Alkenes: An Enantioselective Approach to Oxa‐Bridged Medium‐Sized Carbocycles. Angew. Chem. Int. Ed., 52: 6526-6530, which has been published in final form at https://doi.org/10.1002/anie.201302713. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsGold standard: Allenamides react with aldehydes or ketones having γ, δ, or ε alkenyl groups, upon activation with suitable gold catalysts, to provide oxa-bridged systems containing seven- to nine-membered carbocycles, in a formal cascade cycloaddition. By using chiral phosphoramidite/gold or bisphosphine/gold catalysts it is possible to obtain the oxa-bridged seven- and eight-membered rings with good to high enantioselectivityThis work was supported by the Spanish MINECO, (SAF2010‐20822‐C02‐01/02, and Consolider‐Ingenio 2010 CSD2007‐00006), ERDF funds, and Xunta de Galicia (INCITE09209084PR, GRC2010/12). H.F. acknowledges the Fundação para a Ciência e Tecnologia (Portugal) and POPH/FSE for a PhD grant (SFRH/BD/60214/2009)S

Gold(I)-Catalyzed Intermolecular Cycloaddition of Allenamides with α,β-Unsaturated Hydrazones: Efficient Access to Highly Substituted Cyclobutanes

α,β-Unsaturated N,N-dialkyl hydrazones undergo a mild [2 + 2] cycloaddition to allenamides when treated with a suitable gold catalyst. The method, which represents the first application of N,N-dialkyl hydrazones in gold catalysis, is compatible with a wide variety of substituents at the alkenyl moiety of the hydrazone component, proceeds with excellent levels of regio- and diastereoselectivity, and provides densely substituted cyclobutanes with good to excellent yieldsThis work was supported by the Spanish MINECO (SAF2013-41943-R and FPI to P.B.A.), the ERDF, the European Research Council (Adv. Grant No. 340055), and the Xunta de Galicia (GRC2013-041). We thank the Orfeo-Cinqa networ

Gold(I)-Catalyzed Intermolecular Cycloaddition of Allenamides with α,β-Unsaturated Hydrazones: Efficient Access to Highly Substituted Cyclobutanes

α,β-Unsaturated N,N-dialkyl hydrazones undergo a mild [2 + 2] cycloaddition to allenamides when treated with a suitable gold catalyst. The method, which represents the first application of N,N-dialkyl hydrazones in gold catalysis, is compatible with a wide variety of substituents at the alkenyl moiety of the hydrazone component, proceeds with excellent levels of regio- and diastereoselectivity, and provides densely substituted cyclobutanes with good to excellent yieldsThis work was supported by the Spanish MINECO (SAF2013-41943-R and FPI to P.B.A.), the ERDF, the European Research Council (Adv. Grant No. 340055), and the Xunta de Galicia (GRC2013-041). We thank the Orfeo-Cinqa networ

EL ESTADO DEL CONOCIMIENTO SOBRE POTIGUAR BRADO CONSERVADOR PERIÓDICO

Este artigo tem como objetivo investigar os desdobramentos sociais advindos da inserção da imprensa potiguar no século XIX, relacionando-os com a produção bibliográfica- acadêmica sobre o jornal Brado Conservador e averiguar as consequências da inserção deste na sociedade Norte Rio-Grandense. Buscou-se, ainda, analisar a utilização do jornal como fonte no discurso do conhecimento científico em trabalhos acadêmicos. Nesse sentido, adota-se como metodologia a pesquisa qualitativa e a análise do discurso, com base na leitura e interpretação de cinco estudos que conversam sobre a temática, tais como: Brito (2016), Burgardt (2014), Maciel (2017), Morais (2000) e Paiva (2011). Diante disso, foi observado que o jornal Brado Conservador desenvolveu-se tendo, como foco, cinco eixos de pesquisas: educação, movimentos sociais e de gênero, seca, trabalho e escravidão.  This article aims to investigate the social developments arising from the insertion of the Rio Grande do Sul press in the 19th century, relating them to the bibliographic-academic production on the newspaper Brado Conservador and to investigate the consequences of its insertion in the North Rio-Grandense society. It was also sought to analyze the use of the newspaper as a source in the discourse of scientific knowledge in academic works. In this sense, the methodology adopted is qualitative research and discourse analysis, based on the reading and interpretation of five studies that talk about the theme, such as: Brito (2016), Burgardt (2014), Maciel (2017), Morais (2000) and Medeiros (2011). In view of this, it was observed that the newspaper Brado Conservador developed, focusing on five research areas: education, social and gender movements, drought, work and slavery.Este artículo tiene como objetivo investigar los desarrollos sociales derivados de la inserción de la prensa Potiguar en el siglo XIX, relacionándolos con la producción bibliográfica-académica en el periódico Brado Conservador e investigar las consecuencias de su inserción en la sociedad del norte del Río Grandense. También buscamos analizar el uso del periódico como fuente en el discurso del conocimiento científico en trabajos académicos. En este sentido, la metodología adoptada es la investigación cualitativa y el análisis del discurso, basados ​​en la lectura e interpretación de cinco estudios que hablan sobre el tema, tales como: Brito (2016), Burgardt (2014), Maciel (2017 ), Morais (2000) y Paiva (2011). En vista de esto, se observó que el periódico Brado Conservador se desarrolló, centrándose en cinco áreas de investigación: educación, movimientos sociales y de género, sequía, trabajo y esclavitud

Gold(I)-Catalyzed Enantioselective [2+2+2] Cycloadditions: An Expedient Entry to Enantioenriched Tetrahydropyran Scaffolds

This is the peer reviewed version of the following article: Iván Varela, Hélio Faustino, Elena Díez, Javier Iglesias-Sigüenza, Francisca Grande-Carmona, Rosario Fernández, José M. Lassaletta, José L. Mascareñas* and Fernando López*, Gold (I)-Catalyzed Enantioselective [2+2+2] Cycloadditions: An Expedient Entry to Enantioenriched Tetrahydropyran Scaffolds. ACS Catal. 2017, 7, 2397-2402 [DOI: 10.1021/acscatal.6b03651]. This article may be used for non-commercial purposes in accordance with American Chemical Society Terms and Conditions for self-archivingA straightforward and atom-economical enantioselective approach to highly substituted tetrahydropyrans is reported. The process, which consists of an intermolecular gold-catalyzed [2+2+2] cycloaddition between allenamides, alkenes, and aldehydes, is efficiently catalyzed by both phosphoramidite- and chiral N-heterocyclic carbene-gold catalysts, occurs with complete chemoselectivity and regioselectivity, moderate diastereoselectivity, and moderate to very good enantioselectivitiesThis work was supported by the Spanish MINECO (grant:SAF2013-41943-R, CTQ2013-48164-C2-1-P and -2-P), the Consellería de Cultura, Educación e Ordenación Universitaria (GRC2013-041, 2015-CP082 and Centro Singular de Investigación de Galicia accreditation 2016-2019, ED431G/09) the European Regional Development Fund (ERDF), the European Research Council (Adv. Grant No. 340055), and the Junta de Andalucía (Grant 2012/FQM 1078). We also thank the Orfeo-Cinqa networkS

Determinação de plastificantes em água potável utilizando cromatografia gasosa e espectrometria de massas

This study investigated the levels of plasticizer endocrine disruptors (diethyl phthalate, dibutyl phthalate, and bisphenol A) in drinking water at Paraíba do Sul River region and release of these compounds from bottled water. An analytical method employing solid phase extraction and GC/MS was optimized and validated. The results showed that the method is selective, linear (r² > 0.99), precise (RSD <12%), accurate (recoveries between 62 and 105%), sensitive and robust. Applying the method, the presence of all studied pollutants in drinking water was observed for the three sampled plasticizers. These plasticizers were not found in mineral bottled water, before or after storage

Axially Chiral Triazoloisoquinolin-3-ylidene Ligands in Gold(I)-Catalyzed Asymmetric Intermolecular (4 + 2) Cycloadditions of Allenamides and Dienes

The first highly enantioselective intermolecular (4 + 2) cycloaddition between allenes and dienes is reported. The reaction provides good yields of optically active cyclohexenes featuring diverse substitution patterns and up to three stereocenters. Key to the success of the process is the use of newly designed axially chiral N-heterocyclic carbene–gold catalystsThis work was supported by the Spanish MINECO (SAF2010-20822-C02, CTQ2010-15297, CTQ2010-14974, and Consolider Ingenio 2010 CSD2007-00006), the ERDF funds, the Xunta de Galicia (INCITE09209084PR, GRC2010/12), and the Junta de Andalucía (2008/FQM-3833 and 2009/FQM-4537, predoctoral fellowship to F.G.-C). H.F. acknowledges the Fundação para a Ciência e Tecnologia (FCT, Portugal) and POPH/FSE for a Ph.D. grant (Grant SFRH/BD/60214/2009)S