Yes / Improved synthetic conditions allow preparation of TMSCCl3 in good yield (70 %) and excellent purity. Compounds of the type NBu4X [X=Ph3SiF2 (TBAT), F (tetrabutylammonium fluoride, TBAF), OAc, Cl and Br] act as catalytic promoters for 1,4‐additions to a range of cyclic and acyclic nitroalkenes, in THF at 0–25 °C, typically in moderate to excellent yields (37–95 %). TBAT is the most effective promoter and bromide the least effective. Multinuclear NMR studies (1H, 19F, 13C and 29Si) under anaerobic conditions indicate that addition of TMSCCl3 to TBAT (both 0.13 M ) at −20 °C, in the absence of nitroalkene, leads immediately to mixtures of Me3SiF, Ph3SiF and NBu4CCl3. The latter is stable to at least 0 °C and does not add nitroalkene from −20 to 0 °C, even after extended periods. Nitroalkene, in the presence of TMSCCl3 (both 0.13 M at −20 °C), when treated with TBAT, leads to immediate formation of the 1,4‐addition product, suggesting the reaction proceeds via a transient [Me3Si(alkene)CCl3] species, in which (alkene) indicates an Si⋅⋅⋅O coordinated nitroalkene. The anaerobic catalytic chain is propagated through the kinetic nitronate anion resulting from 1,4 CCl3− addition to the nitroalkene. This is demonstrated by the fact that isolated NBu4[CH2=NO2] is an efficient promoter. Use of H2C=CH(CH2)2CH=CHNO2 in air affords radical‐derived bicyclic products arising from aerobic oxidation. / Engineering and Physical Sciences Research Council (EPSRC) Grant EP/K000578/1.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-10-20T14:28:20Z No. of bitstreams: 1 eloahpereiraavila.pdf: 19264165 bytes, checksum: c322eb3e55e26c89546b4e9982d62ba3 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-10-21T13:12:18Z (GMT) No. of bitstreams: 1 eloahpereiraavila.pdf: 19264165 bytes, checksum: c322eb3e55e26c89546b4e9982d62ba3 (MD5) / Made available in DSpace on 2017-10-21T13:12:18Z (GMT). No. of bitstreams: 1 eloahpereiraavila.pdf: 19264165 bytes, checksum: c322eb3e55e26c89546b4e9982d62ba3 (MD5) Previous issue date: 2017-08-18 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As reações de adição 1,2 às iminas são uma ferramenta sintética de grande interesse para a obtenção de blocos de construção contendo grupos aminas e aminoácidos em seus esqueletos estruturais. Os compostos obtidos por esta via são de grande interesse farmacológico, industrial e demais produtos de química fina. Desta forma, é possível acessar não apenas substratos para a síntese de moléculas complexas, mas também compostos com propriedades biológicas relevantes. Assim, propusemos duas vertentes para obtenção de estruturas análogas: em um primeiro momento, o desenvolvimento de uma metodologia para a obtenção de triclorometilaminas a partir da inserção do triclorometil carbânion gerado pela descarboxilação do sal tricloroacetato de potássio em um solvente aprótico em condições brandas e economicamente viável. Uma versão diastereosseletiva foi apresentada para a obtenção de um derivado enantiomericamente puro. Para uma melhor compreensão do mecanismo, cinética de descarboxilação, e formação de espécies envolvidas, foi utilizada a espectroscopia no Infravermelho por Transformada de Fourier com Reflexão Total Atenuada (ATR-FTIR) em tempo real, sendo possível medir a velocidade de decomposição, importância na adição dos reagentes e inferir a formação do ânion -CCl3. Em um segundo momento, propõe-se a síntese de derivados de α,β-diaminoácidos via catálise por ácido de Brønsted assimétrica a partir de uma reação do tipo Mannich entre azalactonas e iminas. Vários derivados de α,β-diaminácidos quirais foram preparados em bons rendimentos e alto controle da estereosseletividade. / 1,2-addition reactions to imines are a synthetic tool of great interest for obtaining building blocks containing amine and amino acid scaffolds with pharmacological interest, agrochemical industry and other fine chemicals. Therefore, it is possible to access not only substrates for the synthesis of complex molecules but also compounds of relevant biological properties. Thus, we proposed two strategies for preparation of those compounds: first, the development of a methodology to obtain trichloromethylamines from the addition of the trichloromethyl anion generated by the decarboxylation of the potassium trichloroacetate salt under mild and economically viable conditions was presented. A diastereoselective version was presented to obtain an enantiomerically pure derivative. For a better understanding of the mechanism, kinetics of decarboxylation, and the formation of involved species, Fourier Transform Infrared spectroscopy with real attenuated Total Reflection (ATR-FTIR) was used. The data indicated the kinetics behavior, importance of the addition of the reagents as well as the formation of the -CCl3 anion. Second, the synthesis of α,β-diamino acid derivatives via asymmetric Brønsted acid catalyzed Mannich type reaction between azalactones and imines is also described. The chiral α,β-diamino acid derivatives were prepared in good yields and with near perfect diastereo- and enantioselectivities.