12 research outputs found
On the mechanism of the Dakin-West reaction
No full textCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The mechanism of the Dakin-West reaction has been thoroughly investigated by monitoring the reaction using ESI-MS/MS techniques in combination with M06-2X/6-311++ G(d,p) calculations. Several of the key intermediates in the previously proposed "azlactone" mechanism have been experimentally detected and characterized. In particular, interception of the mixed anhydrides involved in the early and late stages of the mechanistic scheme, as well as of the cyclic acyl-oxazolone intermediate, supports the original pathway suggested by Dakin and West. All intermediates and transition structures involved in several competing mechanisms have been calculated. The theoretical calculations support the experimental results and corroborate the proposed "azlactone" mechanism. The pathway involving the cyclic oxazolone ("azlactone") intermediate represents an energy barrier more than 3 kcal mol(-1) lower than for the competing aldol-type mechanism, thus ruling out this alternative mechanism. The DFT calculations explain the observed ESI-MS data and assess those intermediates which the experiments cannot fully elucidate.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.104590139020Spanish Ministerio de Ciencia e InnovacionCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP
Pharmacomodulation on the 3-acetylursolic acid skeleton: Design, synthesis, and biological evaluation of novel N-{3-[4-(3-aminopropyl)piperazinyl]propyl}-3-O-acetylursolamide derivatives as antimalarial agents
No full textInternational audienc
Synthesis of \upalpha α -amino-1,3-dicarbonyl compounds via Ugi flow chemistry reaction: access to functionalized 1,2,3-triazoles
No full textAnti-inflammatory effects in muscle injury by transdermal application of gel with Lychnophora pinaster aerial parts using phonophoresis in rats
No full textSynthesis and preliminary evaluation of new ursolic and oleanolic acids derivatives as antileishmanial agents
No full textOptimization of 2-ethylhexyl Palmitate Production Using Lipozyme RM IM as Catalyst in a Solvent-Free System
No full textTecnologias Digitais e a relação entre teoria e prática: uma análise da produção em trinta anos de BOLEMA
No full textContinuous Flow Synthesis of α-Halo Ketones: Essential Building Blocks of Antiretroviral Agents
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