A series of new glycosylated 2-aryl-5-amidinobenzimidazoles derived from four different carbohydrates (D-glucose, D-galactose, N-acetyl-D-glucosamine and lactose) were synthesized by the condensation of the appropriate 4-formyl-3-methoxyphenyl glycoside with 4-amidino- or 4-N-isopropylamidino-ortho-phenylenediamine hydrochloride. All the compounds were properly characterized by high resolution mass spectrometry, uni- and bidimensional 1H and 13C nuclear magnetic resonance and then were evaluated for their antibacterial and antifungal potential. Considering the antifungal potential of them, two derivatives were active against Candida parapsilosis at 96.4 µmol L-1 and another was active against this same strain at 83.5 µmol L-1. In addition, one benzamidine showed activity against Candida glabrata at 97 µmol L-1. Considering the antibacterial potential of these compounds, six of them showed better activity against three different stains: three of them with IC50 of 96.4, 97 and 83.5 μmol L-1 against Gram-positive Micrococcus luteus, the other two with IC50 96.5 and 96.4 μmol L-1 against Gram-positive Enterococcus faecalis and one against Gram-negative Escherichia coli at 90.5 µmol L-1. These findings suggest this structural pattern can be employed for design of more potent agents for discovery of new antimicrobial drug candidates.

We report herein a study on the glycosylation of cyclohexanol with four D-glucosamine-based peracetylated glycosyl chlorides bearing different substituents at C-2 and three glycosylation promoters, silver carbonate, silver triflate and mercury II chloride/mercury II oxide, by the Koenigs-Knorr method. Under the conditions studied, glycosylation was successful only when 3,4,6-tri-O -acetyl-2-deoxy-2-phthalimido-α-D-glucopyranosyl chloride was used as the glycosyl donor, with silver carbonate proving the best promoter. In order to investigate the influence of the nature of the halogen at C-1, we also carried out the glycosylation of cyclohexanol with 3,4,6-tri-O -acetyl-2-deoxy-2-phthalimido-α-D-glucopyranosyl bromide, a more reactive glycosyl donor. As expected, the yield with the bromide derivative was higher with the three promoters and, again, silver carbonate was the most efficient promoter. Finally, to illustrate the well-known efficient procedure for conversion of the phtalimido group at C-2 to the corresponding acetamido group, cyclohexyl 3,4,6-tri-O -acetyl-2-deoxy-2-phtalimido-β-D-glucopyranoside was converted into cyclohexyl 2-deoxy-2-acetamido-β-D-glucopyranoside in two steps, namely, hydrazinolysis of the phtalimido group followed by chemoselective acetylation of the free amino group by treatment with acetic anhydride in methanol, at 77% overall yield.

Herein, we report the synthesis of β-N-glycosylsulfonamides derivatives of D-glucose and N-acetylglucosamine using conventional methods. We also describe a procedure that allows the preparation of these compounds in good yields without the anomerization of the intermediate glycosylamines. This method includes the intermediates obtained from the less reactive 1- and 2-naphthalenesulfonyl chlorides.

We describe herein a straightforward and efficient preparation of 2',3'-dideoxy-2'-(2''- (trimethylsilyl)ethylthio)thymidine, which allows the preparation of diverse potentially antiviral and/or anticancer nucleosides (disulfides, thiols, sulfides, thiocyanates).

Este trabalho descreve a síntese de neoglicoconjugados diméricos, triméricos e tetraméricos derivados de D-galactose. O ligante monossacarídico foi preparado em cinco etapas utilizando-se a modificação de Doebner da reação de Knoevenagel na etapa de extensão da cadeia lateral. O ligante foi acoplado a 1,4-butanodiamina, tris-(2-etilamino)amina, pentaeritritiltetramina e dendrímeros PAMAM (núcleo 1,4-butanodiamina G0 e núcleo 1,12-dodecanodiamina G0). Os glicodendrímeros desprotegidos foram purificados por cromatografia por exclusão de tamanho (SEC). Esta foi a única etapa em que um método cromatográfico foi empregado em toda rota sintética. Essa é uma estratégia nova e eficiente para a preparação de neoglicoconjugados.

In this work, the synthesis of dimeric, trimeric and tetrameric D-galactose-based neoglycoconjugates is reported. The monosaccharide ligand was prepared in 5 straightforward steps from D-galactose using the Doebner modification of the Knoevenagel reaction for chain elongation. The ligand was coupled to 1,4-butanediamine, tris-(2-ethylamino)amine, pentaerythrityltetramine and PAMAM dendrimers (1,4-butanodiamine core G0 and 1,12-dodecanediamine core G0). The unprotected glycodendrimers were purified by size-exclusion chromatography (SEC). This was the only step in which a chromatographic method was employed throughout the synthetic route. This is a new and efficient strategy for the preparation of neoglycoconjugates.

Ionização por electrospray no modo de íons positivos, e espectrometria de massas de alta resolução e exatidão, e em tandem, realizadas em espectrômetro de massas híbrido quadrupolo e tempo de vôo, foram utilizadas para investigar a dissociação química das moléculas intactas dos dois antimaláricos mais amplamente utilizados: artemeter e lumefantrina. As rotas de dissociação das formas cationizadas e protonadas foram claramente estabelecidas via determinações de massas de alta resolução e distribuição isotópica. Os resultados obtidos podem auxiliar a monitorização e a quantificação de artemeter e lumefantrina por LC-MS/MS, assim como de novos derivados ou outros fármacos antimaláricos estruturalmente relacionados.

Electrospray ionization in the positive ion mode and high resolution and high accuracy tandem mass spectrometry performed in a hybrid quadrupole time-of-flight mass spectrometer were used to investigate the dissociation chemistry of the intact molecules of two most widely used antimalarial drugs: artemether and lumefantrine. The dissociation pathways of their cationized and protonated forms were rationalized based on high accuracy mass measurements and isotopic distributions. The obtained results should benefit LC-MS/MS monitoring and quantitation by mass spectrometry of the artemether and lumefantrine molecules, as well as of new derivatives or other structurally related antimalarial drugs.

A glicosamina-6-fosfato sintase (GlmS) catalisa a formação de glicosamina-6-fosfato a partir de frutose-6-fosfato. Esta é a primeira etapa da via biossintética de aminoaçúcares, componentes estruturais importantes da parede celular de fungos e bactérias. Este trabalho descreve o planejamento, a síntese e a avaliação da atividade inibitória da GlmS de dois novos compostos aromáticos enantioméricos, análogos de 2-amino-2-desoxi-D-glucitol-6-fosfato (ADGP) e de seu epímero 2-amino-2-desoxi-D-manitol-6-fosfato (ADMP), dois importantes inibidores da GlmS. Os análogos aromáticos apresentaram atividade inibitória modesta, na faixa de mmol L-1.

The aminosugars are very important structural components of bacterial and fungi cell walls. Glucosamine-6-phosphate synthase (GlmS), which catalyses the first step of the aminosugar biosynthetic pathway i.e. the formation of D-glucosamine-6-phosphate from D-fructose-6-phosphate, is therefore an interesting target in the fight against microorganisms. In this work is described the synthesis of aromatic analogs of 2-amino-2-deoxy-D-glucitol-6-phosphate (ADGP) and its epimer 2-amino-2-deoxy-D-manitol-6-phosphate (ADMP), two important inhibitors of GlmS. The aromatic analogs displayed modest inhibitory activity against GlmS, with IC50 in the mmol L-1 range.

Reações de 4-O-alil-2,3-di-O-benzil-6-desoxi-6-(3-iodobenzoilamino)-α-D-galactopiranosídeo de metila, seu epímero glico, 2,3-di-O-benzil-6-desoxi-6-(3-iodobenzoilamino)-4-O-(1-pentenil)-α-D-glicopiranosídeo de metila e seu regioisômero orto-iodobenzamida com hidreto de tri-n-butilestanho foram realizadas em diferentes condições. Dependendo das condições, os três precursores que contêm o átomo de iodo em posição meta conduziram a uma surpreendente quantidade de compostos bifenílicos, nos quais o átomo de iodo foi substituído por um grupo fenila. O substrato 2-iodobenzamida levou apenas ao produto de hidrogenólise. Nenhum produto ciclizado foi isolado de nenhuma das reações. As estruturas dos compostos bifenílicos inéditos foram elucidadas utilizando-se as espectrometrias de massa, de RMN ¹H e 13C e experimentos DEPT, COSY, HMQC e HMBC. Foram propostos mecanismos de formação dos compostos bifenílicos e hipóteses para explicar os diferentes comportamentos dos isômeros orto- e meta-iodobenzamidas na reação radicalar.

Reactions of methyl 4-O-allyl-2,3-di-O-benzyl-6-deoxy-6-(3-iodobenzoylamino)-α-D-galactopyranoside, its gluco epimer, methyl 2,3-di-O-benzyl-6-deoxy-6-(3-iodobenzoylamino)-4-O-(1-pentenyl)-α-D-glucopyranoside and its ortho-regioisomer with tri-n-butyltin hydride were performed in different conditions. Depending on reaction conditions the three meta-iodo isomers gave a surprising amount of biphenyl compounds. The 2-iodo isomer led only to the undesired but expected hydrogenolysis product. No cyclized products were isolated in all the reactions. The structures of the new biphenyl products were elucidated by ¹H and 13C NMR spectroscopy, DEPT, COSY, HMQC and HMBC experiments and ESI-MS/MS. Mechanisms for the formation of these new biphenyl derivatives and hypotheses to explain the different outcomes for radical reactions of 3- or 2-iodobenzamides were presented.

A reação radicalar mediada por hidreto de tri-n-butilestanho de 2,3-di-O-benzil-4-O-trans-cinamil-6-desoxi-6-(2-iodobenzoilamino)- alfa-D-galactopyranosídeo de metila levou à formação de um produto inesperado, o 2,3-di-O-benzil-4-O-trans-cinamil-6-desoxi-6-(2-tri- n-butilestanhobenzoilamino)-alfa-D-galactopyranosídeo de metila. A estrutura do produto foi elucidada por meio das espectrometrias de RMN unidimensionais (¹H, 13C e DEPT) e bidimensionais (COSY e HMQC) e confirmada por espectrometria de massas. Foram apresentadas propostas de mecanismos para explicar a formação do derivado organoestanho.

The tri-n-butyltin hydride-mediated reaction of methyl 2,3-di-O-benzyl-4-O-trans-cinnamyl -6-deoxy-6-(2-iodobenzoylamino)-alpha-D-galactopyranoside afforded an unexpected aryltributyltin compound. The structure of this new tetraorganotin(IV) product has been elucidated by ¹H, 13C NMR spectroscopy, COSY and HMQC experiments and electrospray ionization mass spectrometry (ESI-MS). The formation of this new compound via a radical coupling reaction and a radical addition-elimination process is discussed.

Relata-se no presente trabalho a síntese dedelta-lactonas quirais derivadas de carboidratos, por meio de reações de ciclização radicalar regio- e estereosseletivas. A configuração do novo centro estereogênico depende da estrutura do carboidrato.

We describe in the present work the synthesis of carbohydrate-based chiral delta-lactones by regio- and stereoselective radical cyclization reactions. The configuration of the newly stereogenic center was found to depend on the structure of the carbohydrate moiety.

Fourteen compounds were evaluated for their activity against Trypanosoma cruzi blood stream forms at the concentration of 500 µg/ml. Six compounds were active and re-tested at lower concentrations.

No âmbito de um programa de estudo de reações de macrociclização intramolecular de radicais arila de o-iodobenzamidas mediadas por hidreto de tri-n-butilestanho foi obtida a benzomacrolactama 2, proveniente de ciclização regiosseletiva 11-endo a partir de 4-O-alil-2,3-di-O-benzil-6-desoxi-6-(2-iodobenzoilamino)- α-D-galactopiranosídeo de metila (1). A benzamida 1 foi sintetizada a partir do α-D-galactopiranosídeo de metila em oito etapas. Da reação de 1 com hidreto de tri-n-butilestanho, além da macrolactama 2, foi isolado o produto de hidrogenólise 3. As estruturas das substâncias 1, 2 e 3 foram identificadas pelos seus espectros de RMN ¹H, RMN 13C e DEPT e por experimentos de RMN bidimensional (COSY e HMQC).

Encouraged by our previous studies of tri-n-butyltin-mediated radical cyclization reaction of o-iodobenzamides, we applied this methodology to the synthesis of benzomacrolactam 2 from methyl 4-O-allyl-2,3-di-O-benzyl-6-deoxy-6-(2-iodobenzoylamino)- α-D-galactopyranoside 1. Apart from the macrolactam 2, resulting from regioselective 11-endo aryl radical cyclization, the hydrogenolysis produt 3 was obtained. The o-iodobenzamide 1 was prepared in eight conventional synthetic steps from methyl α-D-galactopyranoside. The unequivocal structures of 1, 2 and 3 were supported by ¹H, 13C and DEPT NMR spectroscopy and by COSY and HMQC experiments.