Percorrer por autor "Grosso, Carla"
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- Asymmetric neber reaction in the Synthesis of Chiral 2-(Tetrazol-5-yl)-2H-AzirinesPublication . Alves, Claudia; Grosso, Carla; Barrulas, Pedro; Paixao, Jose A.; Cardoso, Ana L.; Burke, Anthony J.; Lemos, Americo; Pinho e Melo, Teresa M. V. D.A successful one-pot methodology for the synthesis of chiral 2-tetrazolyl-2H-azirines has been established, resorting to organocatalysis. The protocol involves the in situ tosylation of beta-ketoxime-1H-tetrazoles followed by the Neber reaction, in the presence of chiral organocatalysts. Among the organocatalysts studied a novel thiourea catalyst derived from 6 beta-aminopenicillanic acid afforded excellent enantioselectivities.
- Comparison of liquid-phase olefin epoxidation catalysed by dichlorobis-(dimethylformamide)dioxomolybdenum(VI) in homogeneous phase and grafted onto MCM-41Publication . Monteiro, Bernardo; Balula, Salete S.; Gago, Sandra; Grosso, Carla; Figueiredo, Sónia; Lopes, Andre D.; Valente, Anabela A.; Pillinger, Martyn; Lourenço, J. P.; Gonçalves, Isabel S.A mesoporous silica-supported molybdenum oxide catalyst with a loading of 0.17Mo/nm2 was prepared by liquid phase deposition ofMoO2Cl2(dmf)2 (1) onto MCM-41 (dmf = dimethylformamide). Powder X-ray diffraction and N2 adsorption studies of Mo-MCM-41 indicate that the texture properties of the support were preserved during the grafting experiment. On the basis of evidence from FTIR spectroscopy, 13C and 29Si MAS NMR, and Mo K-edge EXAFS, the Mo atoms in this catalyst are mainly present as isolated {MoO2[(–O)3SiO]2(dmf)2} species, with a small contribution from oxo-bridged dimers. Catalysis tests show that complex 1 and Mo-MCM-41 are highly active oxidation catalysts for liquid-phase epoxidation of unfunctionalised olefins using tert-butylhydroperoxide as oxidant, from ambient to 55 ◦C. The high stability and recyclability of the heterogeneous Mo-MCM-41 catalyst is attributed to the strong metal oxide–support interaction. With cyclooctene, 1-octene, trans-2-octene and norbornene substrates, the corresponding epoxides were the only observed reaction products. The reactions of the other substrates gave by-products such as 8,9-p-menthen-1,2-diol from (R)-(+)-limonene, campholenic aldehyde from -pinene, and benzaldehyde from styrene. The addition of dichloromethane as a co-solvent had a beneficial effect on catalytic performance, and in the case of (R)-(+)-limonene allowed the epoxide to be formed as the only reaction product.
- Hetero-Diels-Alder approach to Bis(indolyl)methanesPublication . Grosso, Carla; Cardoso, Ana L.; Rodrigues, Maria Joao; Marques, Catia; Barreira, Luísa; Lemos, Americo; Pinho e Melo, Teresa M. D. V.A novel synthetic approach to bis(indolyl)methanes has been established. Our one-pot synthetic strategy based on two consecutive hetero-Diels-Alder cycloaddition reactions of electrophilic conjugated nitrosoalkenes with indoles was extended to a range of new 1-hydroxyiminomethyl-bis(indolyl) methanes. Furthermore, a similar and broad range approach was applied to the synthesis of previously unknown 1-hydrazonomethyl-bis(indolyl)methanes. The biological evaluation of the new bis(indolyl) methanes as anti-cancer agents was investigated. (C) 2016 Elsevier Ltd. All rights reserved.
- Modelling and optimization of ethyl butyrate production catalysed by Rhizopus oryzae lipasePublication . Grosso, Carla; Ferreira Dias, S.; Cabral, Paula PiresResponse surface methodology was used to model and optimise the production of ethyl butyrate, catalysed by Rhizopus oryzae lipase immobilised in a hydrophilic polyurethane foam. Experiments were carried out following a central composite rotatable design, as a function of reaction temperature (T: 22-38 degrees C) initial butyric acid concentration (A: 0.031-0.619 M) and initial molar ratio ethanol/acid (MR; 0.257-2.443). After 48 h reaction time, the production of ethyl butyrate could be fitted to a surface described by a second-order polynomial model. A maximum ethyl butyrate concentration of 0.106 M, corresponding to 47% conversion into ester and a productivity of 2.21 mu mole/mL h, is expected at initial reaction conditions of T, A and MR of 33 degrees C, 0.225 M and 1.637, respectively. This maximum was experimentally confirmed. (c) 2012 Elsevier Ltd. All rights reserved.
- Natural deep eutectic solvents in the hetero-Diels-Alder approach to bis(indolyl)methanesPublication . Grosso, Carla; Brigas, Amadeu; de los Santos, Jesus M.; Palacios, Francisco; Lemos, Americo; Pinho e Melo, Teresa M. V. D.For the first time, the use of natural deep eutectic solvents (NADES) as reaction media to carry out hetero-Diels-Alder reactions is disclosed. This allowed to improve the efficiency and sustainability of the synthetic approach to bis(indolyl)methanes (BIMs) based on bis-hetero-Diels-Alder/conjugate addition reactions of nitroso- and azoalkenes with indoles. The ternary mixture of H2O with choline chloride/glycerol allowed the tuning of the physical properties of this NADES leading to a better solvent system, affording the target hydroxyiminomethyl- and hydrazonomethyl-BIMs, in much shorter reaction times, higher efficiency and easier isolation procedures. Furthermore, the direct access to carbonyl-BIMs was possible when 3-methyl-1-tert-butoxycarbonyl azoalkenes were used. [GRAPHICS] .
- One-Pot Synthetic Approach to Dipyrromethanes and Bis(indolyl)methanes via Nitrosoalkene ChemistryPublication . Cardoso, Ana L.; Lopes, Susana M. M.; Grosso, Carla; Pineiro, Marta; Lemos, Americo; Pinho e Melo, Teresa M. V. D.A one-pot regio- and stereoselective synthesis of a dipyrromethane and a bis(indolyl)methane based on two consecutive reactions of nitrosoalkenes with pyrrole or indole, respectively, is described as an experiment to be carried out by upper-division undergraduate students in a laboratory classroom. Importantly, the ability of electrophilic conjugated nitrosoalkenes to react via Michael addition or hetero-Diels-Alder reactions with electron-rich heterocycles will provide an opportunity for students to acknowledge alternative reaction pathways underlying certain transformations. Reactions were performed under mild conditions using water as a solvent, followed by purification through column chromatography on silica gel, and characterization of the desired products by NMR and IR spectroscopy. This laboratory experiment combines organic synthesis, determination of the purity of compounds (TLC analysis and melting point measurements), as well as structural analysis (interpretation of 1D NMR spectra). Several important organic chemistry concepts, such as stereo- and regioselectivity, in situ generation and reactivity of conjugated nitrosoalkenes, conjugated 1,4-addition reactions, and cycloaddition reactions, are also discussed.
- Produção de butirato de etilo catalisada por lipases imobilizadasPublication . Grosso, Carla; Cabral, Paula; Dias, Suzana FerreiraEste trabalho de dissertação, teve como objectivo seleccionar o biocatalisador que melhor se adaptasse às condições reaccionais pretendidas, a partir de um screening de lipases comerciais de Aspergilus níger e Rhizopus oryzae, imobilizadas em espuma hidrofílica de poliuretano Hypol FHP 2002TM e de lipases não comerciais de Yarrowia lipolytica imobilizadas em diferentes suportes: Lewatit VP OC 1065, HPL, Amberlite 96, Lewatit K 2629, Lewatit VO OC 1026 e Lewatit MP TP 214 e de Rhizopos oryzae imobilizada em espuma de poliuretano Hypol FHP 2002TM, de modo a modelar e optimizar a reacção de esterificação de etanol com ácido butírico en n-hexano, para produção de butirato de etilo. A lipase comercial de Rhizopus oryzae imobilizada em Hypol FHP 2002TM foi o biocatalisador que conduziu a valores mais elevados de produtividade volumétrica (2,12 μmol/mL.h), velocidade inicial de esterificação (148 μmol/min.gbiocatalisador), concentração (0,102 M) e conversão (31,9 %) em butirato de etilo, quando testada nas condições do ponto central do delineamento experimental realizado. A Metodologia das Superfícies de Resposta foi utilizada para modelar a reacção de esterificação acima referida, como função da temperatura, T (21,6 ºC - 38,4 ºC), da concentração inicial de ácido butírico, A (0,031 M - 0,619 M) e da razão molar inicial etanol/ácido butírico, RM (0,257 M - 2,443 M). Os ensaios foram realizados de acordo com um delineamento experimental central rotativo compósito, tendo-se verificado que a produção e conversão em butirato de etilo podem ser descritas por equações polonomiais de segunda ordem. A concentração máxima de butirato de etilo (0,106 M) e a taxa conversão máxima em éster (32,6 %), previstas pelos modelos, verificam-se quando as condições reaccionais iniciais de T, A e RM são 31,5 ºC, 0,225 M e 1,637 e 18,9 ºC, 0,27M e 1,687, respectivamente. Verificou-se que o aumento da concentração de ácido butírico, na presença de excesso de etanol provoca um aumento na concentração de etanol no microambiente do biocatalisador. A temperatura tem uma influência significativa no aumento da concentração de etanol no microambiente do biocatalisador.
- Regioselectivity in hetero diels-alder reactionsPublication . Grosso, Carla; Liber, Marta; Brigas, Amadeu; Pinho e Melo, Teresa M. V. D.; Lemos, AmericoRegioselectivity in hetero Diels-Alder reactions can be observed in a simple reaction between a nonsymmetrical heterodiene and an unsymmetrical heterodienophile. A 9 h and easy to implement laboratory experiment is described, in which students can observe the regioselectivity of inverse "electron-demand" hetero Diels-Alder reactions of an azoalkene with furan or 2,3-dihydrofuran acting as dienophile. This experiment combines synthesis, structural analysis (IR spectroscopy and NMR spectroscopy), and dry- and vacuum-flash isolation methods.
- Selective synthesis of 3-(1H-Tetrazol-5-yl)-indoles from 2H-Azirines and ArynesPublication . Grosso, Carla; Alves, Cláudia; Sase, Terver J.; Alves, Nuno G.; Cardoso, Ana L.; Melo, Teresa M. V. D. Pinho e; Lemos, AmericoA new selective synthetic approach to indole derivatives bearing a tetrazole moiety has been developed. Arynes, generated in situ from o-(trimethylsilyl)aryl triflates and KF, reacted smoothly with 2-(2-benzyl-2H-tetrazol-5-yl)-2H-azirines to give 3-(2-benzyl-2H-tetrazol-5-yl)-indole derivatives with high selectivity. Deprotection of the tetrazole moiety gave 3-(1H-tetrazol-5-yl)-indole derivatives.