7a-Hydroxyroyleanone is a bioactive diterpene isolated from leaves of Tetradenia riparia, active against tuberculosis and T. cruzi. In order to use this compound as starting material for the synthesis of compounds with enhanced bioactivity we aimed the dehydration of the 7-alpha-hydroxyl group of royleanone. The reaction performed in acetic acid and hydrochloric acid under reflux gave an unexpected chlorinated naphtoquinone, with aromatization and opening of one of the rings of the starting material, as major product, besides 6,7-dehydroroyleanone and a complex mixture of other products. The reaction products were purified by high-speed countercurrent chromatography with hexane-acetonitrile 1:1. Compounds were tested for their anti-leishmanial activity (L. amazonensis) pointing out a potential leishmanicidal agent which may favor the development of more effective therapies.

Cromatografia gasosa bidimensional abrangente acoplada à espectrometria de massas por tempo de voo (GC×GC-TOFMS) é uma técnica apropriada para a elucidação da composição molecular de amostras petroquímicas, como óleos biodegradados. Biomarcadores foram separados, identificados e razões de biomarcadores convencionais foram determinados usando cromatografia gasosa acoplada à espectrometria de massas (GC-MS) e GC×GC-TOFMS. No cromatograma de íons extraídos m/z 123 + 177 + 191, coeluições entre terpanos tricíclicos, hopanos e 25-nor-hopanos com secohopanos foram resolvidas usando GC×GC-TOFMS. GC×GC-TOFMS permitiu a identificação da série completa dos 25-nor-hopanos, nor-gamacerano, C29 28-nor-espergulano e oleanano, que não foram identificados por GC-MS. A avaliação dos parâmetros geoquímicos dos óleos estudados indicou uma origem marinha e um ambiente deposicional sob condições anóxicas. A alta resolução cromatográfica e sensibilidade alcançada usando GC×GC-TOFMS permitiram sugerir três novos parâmetros geoquímicos para a caracterização de óleos altamente biodegradados. Estes resultados demonstram a superioridade da técnica GC×GC-TOFMS na separação e identificação de compostos individuais e não-alvos em óleos severamente biodegradados

Comprehensive two-dimensional gas chromatography with time of flight mass spectrometry (GC×GC-TOFMS) is an appropriate technique for the elucidation of molecular composition of petrochemical samples, such as biodegraded oils. Biomarkers were separated and identified, and conventional biomarker ratios were determined via gas chromatography-mass spectrometry (GC-MS) and GC×GC-TOFMS. In the extracted ion chromatogram m/z 123 + 177 + 191, coelutions between tricyclic terpanes, hopanes and 25-nor-hopanes with secohopanes were resolved by GC×GC-TOFMS. GC×GC-TOFMS allowed the identification of complete series of 25-nor-hopanes, nor-gammacerane, C29 28-nor-spergulanes and oleanane not identified by using GC-MS. The biomarker ratios from the studied oils indicated that they derived from marine source rock deposited under anoxic conditions. The higher chromatographic resolution and sensitivity achieved by using GC×GC-TOFMS allowed for three new parameters to characterize biodegraded oils. These results indicated the superiority of GC×GC-TOFMS for separation and identification of individual and non-target compounds in severely biodegraded oils.

Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry was used for the identification of forty doping agents. The improvement in the specificity was remarkable, allowing the resolution of analytes that could not be done by one-dimensional chromatographic systems. The sensitivity observed for different classes of prohibited substances was clearly below the value required by the World Anti-Doping Agency. In addition time-of-flight mass spectrometry gives full spectrum for all analytes without any interference from the matrix, resulting in selectivity improvements. These results could support the implementation of an exhaustive monitoring approach for hundreds of doping agents in a single injection.

A cromatografia gasosa bidimensional abrangente acoplada à espectrometria de massas por tempo de vôo (CG×CG-EMTDV) foi aplicada para avaliar o efeito do CO2 sobre a distribuição dos n-alcanos, alcanos ramificados, alquenos e compostos oxigenados em produtos da reação de Fischer-Tropsch. Coeluições de material não resolvido observadas em CG convencional foram resolvidas por CG×CG-EMTDV.

Comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry (GC × GC-TOFMS) was applied to evaluate the CO2 effect on distribution of n-alkanes, branched alkanes, alkenes and oxygen-containing compounds in Fischer-Tropsch products. GC × GC-TOFMS was able to resolve the unresolved compounds observed in conventional GC.

Quimiosseletividade é observada, após reação de oxidação, utilizando-se m-CPBA, a partir da piranobenzo[a]fenazina e da furanobenzo[a]fenazina, derivadas, respectivamente da beta-lapachona e da nor-beta-lapachona. A fenazina pirânica forneceu macrolactonas, principalmente, enquanto a fenazina furânica conduziu a um único produto: o N-8 óxido da fenazina. Objetivando entender essa diferença de reatividade, uma nova fenazina furânica foi sintetizada, tendo como característica principal, a presença da ligação dupla em um sítio menos encoberto estericamente do que aquele presente no derivado nor-beta-lapachônico. Essa furanofenazina, após oxidação com m-CPBA, forneceu, principalmente, a macrolactona esperada. Esses resultados experimentais, aliados a cálculos mecânico-moleculares do estado fundamental dos substratos, permitiram sugerir que a quimiosseletividade observada pode ter controle estérico, relacionado à presença dos grupos substituintes metila geminados, que dificultam a aproximação do oxidante. Muitos dos compostos sintetizados são relatados, pela primeira vez, no presente artigo.

Chemoselectivity is observed when a pyran-benzo[a]phenazine and a furan-benzo[a]phenazine from beta-lapachone and nor-beta-lapachone, respectively, were submitted to oxidation by m-CPBA. The pyran phenazine furnished mainly macrolactones, while the furan one led exclusively to a phenazine N-8 oxide. To understand this difference in reactivity, we synthesized a new furan phenazine, with the reactive double bond site less hindered than that of the derivative from nor-beta-lapachone. This furan phenazine, upon oxidation with m-CPBA, furnished mainly the expected macrolactone. These experimental results, along with preliminary analysis based on mechanical molecular calculations of the ground state of the substrates, allowed us to suggest that the observed chemoselectivity has a steric oxidant approach control origin, related to the presence of the geminal methyl groups in the phenazine structure. Several of the synthesized compounds are, herein, reported for the first time.

A benzofenazina derivada da beta-lapachona foi submetida a ozonólise em condições que forneceram seletivamente a lactona macrocíclica 7,7-dimetil-7,8,9,10-tetrahidro-5H-benzo[3,4]oxecino[5,6 -b]quinoxalina-5,10-diona, com rendimento de 52%. O efeito de substituintes localizados no anel diidropirânico das fenazinas, no caso C2' -OH, C2' -Br e C2' -I, em reações de oxidação com MCPBA, foi também investigado.

The benzophenazine from beta-lapachone was submitted to ozonolysis under conditions that selectively furnished the corresponding rigid macrocyclic lactone 7,7-dimethyl-7,8,9,10-tetrahydro-5H-benzo[3,4]oxecino[5,6-b]quinoxaline-5,10-dione in an yield of 52%. The effect of substituents located at the dihydropyrane moiety of the phenazines, namely C2'-OH, C2'-Br and C2'-I, in the oxidation with MCPBA, was also investigated.