Papers by Ronaldo Aloise Pilli
The Journal of Organic Chemistry, 2017
The total synthesis and structural revision of (+)-cryptoconcatone H are described. Guided by com... more The total synthesis and structural revision of (+)-cryptoconcatone H are described. Guided by computational studies for the final structure assignment, the stereogenic centers at the tetrahydropyran moiety of (+)-cryptoconcatone H were assembled through catalytic asymmetric methodologies: Krische allylation, cross-metathesis reaction, and THP formation via Pd(II)-catalyzed cyclization. Finally, a Krische allylation reaction established the last stereocenter, and the lactone moiety was formed by ring-closing metathesis. Note pubs.acs.org/joc
Effect of goniothalamin on the development of Ehrlich solid tumor in mice
Bioorganic & Medicinal Chemistry, 2010
In this work the antiproliferative activity of goniothalamin (1), both in racemic and in its enan... more In this work the antiproliferative activity of goniothalamin (1), both in racemic and in its enantiomeric pure forms, in a solid tumor experimental model using laboratory animals is described. The antiedematogenic activity displayed by racemic 1 in the carrageenan edema model in mice together with the reduction of Ehrlich solid tumor model suggest a relationship between anticancer and antiinflammatory activities with the antiinflammatory activity favoring the antiproliferative activity itself.
IOs desafios teóricos e metodológicos para o estudo das migrações internas e internacionais têm p... more IOs desafios teóricos e metodológicos para o estudo das migrações internas e internacionais têm pautado os estudos da comunidade científica nas últimas décadas. Na reconstrução histórica do fenômeno migratório pode-se encontrar elementos que permitem acompanhar o deslanchar de processos posteriores. Nas condições sociais contemporâneas, a complexidade, a importância, as novas rotas e direções coexistem com processos migratórios antigos (internos e internacionais), que se redefinem na ...
Triflato de zinco como ácido de Lewis na adição nucleofílica a íons N-acilimínios cíclicos
The stereoselective addition of the titanium (IV) enolates derived from (S)-4-isopropyl-N-4-chlor... more The stereoselective addition of the titanium (IV) enolates derived from (S)-4-isopropyl-N-4-chlorobutyryl-1,3-thiazolidine-2-thione (8) and from (S)-4-isopropyl-N-4-chloropentanoyl-1,3-thiazolidine-2-thione (9) to N-Boc-2-methoxypyrrolidine (5b) afforded the addition products (+)-10 and (+)-11 in 84% yield in both cases, as 8.6:1 and 10:1 diastereoisomeric mixtures, respectively. A threestep sequence allowed to convert these adducts to (+)-isoretronecanol (1) and (+)-5-epi-tashiromine (2) in 43% and 49% overall yield, respectively.
The relative configuration of a D-lactone isolated from the mandibular gland extracts of Calomyrm... more The relative configuration of a D-lactone isolated from the mandibular gland extracts of Calomyrmex sp. males has been determined to be (3SR,5R5,6SR)-3,5,6-trimethyltetrahydropyran-2H-one after the synthesis of the four possible racemates and comparison of their mass spectra and gas chromatographic properties with those reported in the literature for the natural product.
O uso de derivados fosfonatos de dialquila diastereoisoméricos na determinação de excessos enanti... more O uso de derivados fosfonatos de dialquila diastereoisoméricos na determinação de excessos enantioméricos através da razão entre os sinais de 31 P-NMR anisócronos dos isômeros meso e treo, foi bem sucedido para álcoois secundários (método de Feringa), porém revelou-se ineficiente para álcoois primários com dois ou mais grupos metilênicos entre as hidroxilas e os centros estereogênicos. Observou-se adicicionalmente que era importante obter os espectros acoplados e desacoplados para se certificar dos picos correspondentes aos fosfonatos de dialquila. Entretanto, esta metodologia merece ser aplicada sempre que a quantidade de álcool disponível e sua estrutura não forem fatores limitantes. The use of diastereomeric alcohol dialkylphosphonate derivatives to determine the enantiomeric excesses via 31 P-NMR signal ratios of anisochronous meso and threo isomers was successfully applied to secondary alcohols (Feringa's method). Expansion of the methodology to primary alcohols possessing the hydroxyl groups thethered to the stereogenic centers by two or more methylene groups proved the method to be inefficent. The comparison between the coupled and decoupled spectra is important in order to identify the signals corresponding to the dialkylphosphonates. Nevertheless the methodology should be applied whenever the amount of the alcohol and its structure are not the limiting factors.
A adição de aliltrimetilsilano, promovida por TiCl 4 , a íons N-aciliminios cíclicos de 5-e 6memb... more A adição de aliltrimetilsilano, promovida por TiCl 4 , a íons N-aciliminios cíclicos de 5-e 6membros derivados do ácido (S)-(+)-mandélico, (1R,2S)-trans-2-fenil-1-cicloexanol e (1R,2S,5R)-8-fenilmentol ocorreu com baixas a moderadas razões diastereoisoméricas (1:1-6:1) e forneceu as respectivas amidas e carbamatos em bons rendimentos. A melhor diastereosseleção facial foi observada com o uso de (1R,2S,5R)-8-fenilmentol como auxiliar quiral. As amidas e carbamatos 2-substituídos foram convertidos nos alcalóides (S)-e (R)-propil pirrolidina e coniina com eficiente recuperação dos auxiliares quirais. The TiCl 4 promoted addition of allyltrimethylsilane to chiral 5-and 6-membered N-acyliminium ions employing (S)-(+)-mandelic acid, (1R,2S)-trans-2-phenyl-1cyclohexanol and (1R,2S,5R)-8-phenylmenthol derivatives as chiral auxiliaries occurred with low to moderate diastereoisomeric ratios (1:1-6:1) to afford 2-substituted amides and carbamates in good yields. The best diastereoselection was observed with (1R,2S,5R)-8phenylmenthol as the chiral auxiliary. The 2-substituted amides and carbamates were converted to the corresponding alkaloids (S)-and (R)-propyl pyrrolidine and coniine with efficient recovery of the chiral auxiliaries.
Compostos (E)-1,2-dibromo vinílicos 11a-f foram preparados estereosseletivamente via reação de br... more Compostos (E)-1,2-dibromo vinílicos 11a-f foram preparados estereosseletivamente via reação de bromação de alcinos empregando-se tribrometo de piridínio em MeOH/CCl 4 a baixa temperatura e utilizados na reação de duplo acoplamento com PhZnCl catalisada por Pd(0), segundo protocolo de Negishi, fornecendo as respectivas olefinas tri e tetrassubstituídas 14a-e. Tamoxifeno, um agente antiestrogênico de uso clínico na terapia do câncer de mama, foi preparado na forma de uma mistura Z:E de proporção 2.3:1, em 7 etapas em um rendimento global de 30% a partir do 4-iodofenol (3). (E)-1,2-vinylic dibromides 11a-f were stereoselectively prepared via bromination of acetylenic compounds with pyridinium tribromide in MeOH/CCl 4 at low temperature and double crosscoupled with PhZnCl under Pd(0) catalysis (Negishi protocol) to afford tri-and tetrasubstituted olefins 14a-e. Tamoxifen, a selective estrogen receptor modulator clinically prescribed in breast cancer therapy, was prepared in 7 steps and 30% overall yield from 4-iodophenol (3) as a 2.3:1 mixture of (Z)-and (E)-isomers.
An alternative asymmetric synthesis of ropivacaine and analogues employing the 'cation pool' stra... more An alternative asymmetric synthesis of ropivacaine and analogues employing the 'cation pool' strategy and host/guest supramolecular co-catalysis approach is presented. In this study, chiral auxiliaries, several soft nucleophiles as well as one-pot conditions for anodic oxidation, followed by nucleophilic addition, have been applied.
Synthesis and biological activities of< i> N, N</i>-dimethyl-2-propen-1-amine derivatives
... proton (8 6.4 ppm) led to a 13% increment in the signal of the ortho protons of the methylsul... more ... proton (8 6.4 ppm) led to a 13% increment in the signal of the ortho protons of the methylsul-fonyl group (~ 7.4 ppm) while irradiation of the olefinic proton (8 6.4 ppm) in the (Z)-Vf isomer gave rise to a 9% increment in the signal of the ortho protons of the ... 2 N Duran and M Haun. ...
A síntese quimioenzimática da forma enantiomericamente enriquecida (80% ee) da (-)-serricornina (... more A síntese quimioenzimática da forma enantiomericamente enriquecida (80% ee) da (-)-serricornina (1), feromônio sexual da praga do fumo Lasioderma serricorne F., foi alcançada em 8 etapas e 13% de rendimento total a partir de (R)-3-hidroxipentanoato de metila, obtido da redução de 3-oxopentanoato de metila com fermento de padaria (S. cerevisiae) na presença de álcool alílico como inibidor enzimático. A short and efficient preparation of enantiomerically enriched (80% ee) (-)-serricornine (1), the sex pheromone of the cigarette beetle Lasioderma serricorne F., was developed in 8 steps and 13% overall yield from methyl (R)-3-hydroxypentanoate readily prepared by baker's yeast reduction of methyl 3-oxopentanoate in the presence of allyl alcohol as enzyme inhibitor.
A short synthesis of (1< i> S</i>, 8a< i> R</i>)-1-aminomethyl indolizidine. The heterocyclic core of stelletamides
Regio-and diastereoselective synthesis of 5-< i> trans</i>-substituted and 5, 5-disubstituted 2-pyrrolidinones derived from (< i> S</i>)-malic acid
The< i> Stemona</i> Alkaloids
Trimethylsilyl Trifluoromethanesul Fonate (Tmsotf) Catalyzed Amidoalkylation of Silylenolethers. Stereocontrolled Syntheses of (+/-)-Sedamine and (+/-)-Norsedamine
Trimethylsilyl trifluoromethanesulfonate (TMSOTf) catalyzed addition of 1-trimethylsilyloxy-1-phe... more Trimethylsilyl trifluoromethanesulfonate (TMSOTf) catalyzed addition of 1-trimethylsilyloxy-1-phenylethene to N-ethoxycarbonyl-and N-tert-butoxycarbonyl-2-ethoxypiperidines (3d and 3b, respectively) afforded the corresponding ketocarbamates 4a and 4b, in excellent yields. Stereoselective conversion to (±)-norsedamine (7) and (±)-sedamine (8) is described.
Total syntheses of (< i> R</i>)-argentilactone and (< i> R</i>)-goniothalamin via catalytic enantioselective allylation of aldehydes
Journal of the Brazilian Chemical Society, 2003
A adição de 5-metil-2-tri-isopropilsililoxifurano (5) a N-carbobenziloxi-2-metoxipiperidina (6a) ... more A adição de 5-metil-2-tri-isopropilsililoxifurano (5) a N-carbobenziloxi-2-metoxipiperidina (6a) forneceu uma mixtura dos isômeros eritro e treo 7a and 8a, respectivamente, em rendimentos de moderado a bom (42-85%) e razão diastereoisomérica (7a : 8a) variando entre 1,1:1-6:1, dependendo do sistema de solvente e do ácido de Lewis empregados. O isômero treo 8a foi transformado na (+/-)-homopumiliotoxina 223G (1) que foi obtida a partir de 6a em 5 etapas e 13% de rendimento total. The addition of 5-methyl-2-triisopropylsilyloxyfuran (5) to N-carbobenzyloxy-2methoxypiperidine (6a) afforded a mixture of the corresponding erythro and threo isomers 7a and 8a, respectively, in moderate to good yields (42-85%) and diastereoisomeric ratio (7a : 8a) ranging from 1.1:1-6:1 depending on the solvent system and the Lewis acid employed. The threo isomer 8a was eventually converted to (+/-)-homopumiliotoxin 223G (1) which was prepared in 5 steps and 13% overall yield from 6a.
A forma natural do (+)-sitofilure, feromônio de agregação de Sitophilus oryzae L. e Sitophilus ze... more A forma natural do (+)-sitofilure, feromônio de agregação de Sitophilus oryzae L. e Sitophilus zeamais M., foi preparada em 12 etapas, 18% de rendimento total e 82% de excesso enantiomérico a partir da redução microbiológica de 3-oxopentanoato de metila com S. cerevisiae na presença de cloroacetato de etila. The asymmetric synthesis of (+)-sitophilure, the aggregation pheromone of Sitophilus oryzae L. and Sitophilus zeamais M., was carried out in 12 steps, 18% overall yield and 82% enantiomeric excess from the enzymatic reduction of methyl 3-oxopentanoate with S. cerevisiae in the presence of ethyl chloroacetate.
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Papers by Ronaldo Aloise Pilli