RESUMO
A straightforward sequential synthetic strategy has been developed for the synthesis of a pentasaccharide repeating unit corresponding to the cell wall O-antigen of the Escherichia albertii O4 strain in very good yield with the desired configuration at the glycosidic linkages using thioglycosides and trichloroacetimidate derivatives as glycosyl donors and perchloric acid supported over silica (HClO4/SiO2) as a solid supported protic acid glycosyl activator. The expected configuration at the glycosidic linkages was achieved using a reasonable selection of protecting groups in the manosaccharide intermediates.
RESUMO
A series of glycosylated 1,4-substituted triazolyl chalcone derivatives (8a-f and 14a-r) were synthesized in high yield using 1,3-cycloaddition (Click chemistry) of d-glucosyl azides with a variety of propargylated chalcone derivatives followed by de-O-acetylation. The synthesized compounds were evaluated for their cytotoxic potential against the human breast carcinoma cell lines and non-cancerous cells. The MTT assay identified three promising cytotoxic compounds (14c, 14i and 14l) and further biochemical and microscopic studies were carried out with the best compound 14i among the active compounds.
Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Proliferação de Células , Chalcona/química , Triazóis/química , Neoplasias da Mama/patologia , Química Click , Reação de Cicloadição , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Glicosilação , Humanos , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
Glycosyl selenoacetate derivatives were prepared by the treatment of glycosyl halide with potassium selenocyanate followed by acetylation of in situ generated glycosyl selenols in one pot. A variety of selenoglycosides and selenium linked disaccharide derivatives were prepared in very good to excellent yields using glycosyl selenoacetates as stable building blocks under mild reaction conditions.
RESUMO
A concise synthetic strategy have been developed for the synthesis of the sialic acid-containing tetrasaccharide repeating unit of the cell wall O-antigen of Escherichia coli (E. coli) O131 strain using regio- and stereoselective (2 â 6)-α-glycosylations of judiciously protected sialic acid thioglycoside derivatives. Perchloric acid supported over silica (HClO4-SiO2) in combination with N-iodosuccinimide (NIS) has been used in the stereoselective activation of thioglycoside derivatives as well as used as a solid acid for the functional group modifications. Appropriate stereoselectivity was achieved in the glycosylation steps involved in the synthetic strategy.
Assuntos
Antígenos O , Tioglicosídeos , Sequência de Carboidratos , Parede Celular , Escherichia coli , Ácido N-Acetilneuramínico , Oligossacarídeos , Dióxido de SilícioRESUMO
An efficient synthetic strategy has been developed for the synthesis of the sialic acid containing pentasaccharide repeating unit of the cell wall O-antigen of Streptococcus group B type VI strain involving stereoselective α-glycosylation of sialic acid thioglycoside derivative. Stereoselective glycosylation of glycosyl trichloroacetimidate derivatives and thioglycosides were carried out using perchloric acid supported over silica (HClO4-SiO2) as a solid acid catalyst. A panel of sialic acid donors has been screened for achieving satisfactory yield and stereochemical outcome of the glycosylation reaction.
Assuntos
Ácido N-Acetilneuramínico/química , Oligossacarídeos/síntese química , Streptococcus/química , Configuração de Carboidratos , Oligossacarídeos/químicaRESUMO
Glycosyl selenocyanate derivatives were prepared in very good yield by the treatment of glycosyl halide or triflate derivatives with potassium selenocyanate in water. A variety of selenium linked pseudodisaccharide derivatives were prepared in excellent yield using glycosyl selenocyanates as stable building blocks in the presence of hydrazine hydrate under metal-free organocatalytic reaction conditions.