Academic literature on the topic 'Beckmann rearrangement'

A B S T R A C T V2O5/SnO2 solid acid catalysts have been employed for the vapour-phase Beckmann rearrangement of cyclohexanone oxime to e-caprolactam. Catalysts with different vanadia loading (3–15 wt%) were prepared by impregnation method and characterized by XRD, BET surface area, FTIR and 51V NMR techniques. The surface acidic properties were determined by temperature programmed desorption and cumene cracking reaction. Under optimized reaction conditions, catalyst with 9 wt% V2O5 gives the maximum amount of desired product (yield 78.8%). However, the catalysts are susceptible for deactivation due to the basic nature of the reaction products (50% deactivation in 5 h). A good correlation was obtained among the rearrangement activities of V2O5/SnO2 catalysts, their weak plus medium acidities (usually of the Bro¨ nsted type) and structural properties.

Orientador: Ronaldo Aloise Pilli<br>Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica<br>Made available in DSpace on 2018-08-08T12:27:57Z (GMT). No. of bitstreams: 1 Sousa_AndreaLealde_D.pdf: 4710314 bytes, checksum: f350442966dde606dde2ff354606b251 (MD5) Previous issue date: 2006<br>Resumo: Os alcalóides marinhos haliclorina (1), ácido pináico (2) e ácido tauropináico (3), isolados, por D. Uemura e colaboradores em 1996, apresentam em comum um sistema 6-aza-[4.5.0]-espirobiciclodecano. A atividade biológica da haliclorina (1) está relacionada com a inibição de moléculas associadas à adesão de células vasculares (VCAM-1) com IC50 de 7mg/mL. O ácido pináico (2) e ácido tauropináico (3) são inibidores da fosfolipase A2 (FLA2). Devido à similaridade estrutural existente entre haliclorina (1), ácido pináico (2) e ácido tauropináico (3), a proposta sintética para estes produtos naturais apresenta um intermediário chave em comum, o núcleo 6-aza-[4.5.0]- espirobiciclodecano. A estratégia sintética foi baseada em uma reação de Michael estereosseletiva entre enolato de lítio da N-propionilpirolidina e 1-ciclopenten-1-carboxilato de metila, seguida da alquilação in situ com 4-iodo-butirato de etila formando 4 em 68% rendimento. A próxima etapa consistiu na condensação de Dieckmann seguida de hidrólise/descarboxilação conduzindo a cetona 5 (61% rendimento) que sofreu redução com LiEt3BH, seguida de lactonização espontânea para gerar 6 (67% rendimento). Após algumas manipulações de grupo funcionais foi obtida a oxima 7 (76% rendimento de 6) precursora do rearranjo de Beckmann que forneceu a lactama espirobicíclica 8 em 60% rendimento<br>Abstract: In 1996, D. Uemura and co-workers isolated the marine alkaloids halichlorine (1), pinnaic acid (2) and tauropinaic acid (3). They are structurally co-related by a 6- azaspiro[4.5.0]decane core. The biological activity of the haliclorina (1) is related to the inhibition of molecules associated to the adhesion of vascular cells (VCAM-1) with IC50 7mg/mL. The pinnaic acid (2) and tauropinnaic acid (3) are inhibitors of the fosfolipase A2 (FLA2). Due to the structural similarity among halichlorine (1), acid pinnaic (2) and acid tauropinnaic (3), this work presents a new synthetic approach to a common key intermediate, the 6-azaspiro[4.5.0]decane nucleus. Our approach was based on the tandem Michael addition/alkylation of the lithium enolate of N-propionyl pyrrolidine to 1-carbomethoxy cyclopentene, followed by in situ alkylation with ethyl 4-iodobutanoate to provide 4 in 68% yield. Dieckmann cyclization, followed by decarboxylation, afforded spirobicyclic ketone 5 (61% yield) which underwent reduction with LiEt3BH reduction, followed by spontaneous lactonization to give 6 (67% yield). Straightforward functional group manipulations provided oxime 7 (76% yield from 6) which underwent Beckmann rearrangement to afford the spirobicyclic lactam 8 in 60% yield, a potential intermediate to the synthesis of those alkaloids<br>Doutorado<br>Quimica Organica<br>Doutor em Ciências

The first section of this work describes the synthesis of a library of novel rhein analogues that are potential anticancer agents. The design of these compounds takes advantage of the ability for rhein to intercalate into DNA and as the incorporation of an alkylating agent, which serves to covalently modify DNA. In three cell lines, these compounds showed potent cytotoxicity with IC50 in the low to mid-μM range. The second project was focused on the development of an efficient synthesis of 6H-Isoindolo[2,1-α]indol-6-one (24), a core structure for a number of biologically active compounds. The approach is metal-free and uses a Beckmann rearrangement followed by an intramolecular cyclization.

碩士<br>國立中正大學<br>化學暨生物化學研究所<br>104<br>B3LYP/6-31+G* calculations were performed to evaluate the role of ionic liquid, 1-butyl-3-methylimidazolium bromide (abbr. [bmim]Br) in Beckmann rearrangement. Our computed results showed that the energy barrier of 1,2-H shift step in the conventional acid-catalyzed Beckmann rearrangement is 55.1 kcal/mol at the B3LYP/6-31+G* level. The energy barrier of 1,2-H shift is decreased by 17 kcal/mol in the presence of Lewis acid (AlCl3) and ionic liquid ([bmim]Br) in acid-catalyzed Beckmann rearrangement. In conclusion, the bromide anion complexed with Lewis acid (AlCl3) is found to act as solvent to promote the proton transfer from nitrogen atom to OH group in the 1,2-H shift at lower cost.