Ethyl 1-O-tert-butyl­dimethyl­silyl-2,3-O-isopropyl­idene-5-[(2′S)-tetra­hydro­pyran-2-yl­oxy]-d-glycero-α-d-manno-hepto­furonate

The title compound {systematic name: (2S,3R)-ethyl 3-[(3aS,4R,6S,6aS)-6-tert-butyl­dimethyl­silyl­oxy-2,2-dimethyl­per­hydro­furo[3,4-d][1,3]dioxol-4-yl]-2-nitro-3-[(S)-tetra­hydro-2H-pyran-2-yl­oxy]propanoate}, C23H41NO10Si, is the product of the Henry reaction of 1-O-tert-butyl­dimethyl­silyl-2,3-O-isopropyl­idene-α-d-lyxo-penta­dialdo-1,4-furan­ose with ethyl nitro­acetate and the subsequent protection of its C-5 hydr­oxy group as tetra­hydro­pyranyl, in order to avoid the retro-Henry reaction. The tetra­hydro­pyranyl group adopts a chair conformation. The absolute configuration, assumed from the synthesis, was confirmed from the diffraction data

Gold(III) Complexes Activity Against Multidrug-Resistant Bacteria Of Veterinary Significance

The emergence and spread of multidrug-resistant bacteria are a global concern. The lack of new antibiotics in the pipeline points to the need for developing new strategies. In this sense, gold(III) complexes (G3Cs) could be a promising alternative due to their recently described antibacterial activity. The aim of this study was to evaluate the antimicrobial activity of G3Cs alone and in combination with colistin against pathogenic bacteria from veterinary sources. Minimal inhibitory concentration (MIC) values were determined by broth microdilution and compared with clinically relevant antibiotics. Antibiofilm activity was determined by crystal violet staining. Combinations of selected G3Cs with colistin and cytotoxicity in commercial human cell lines were evaluated. Four and seven G3Cs showed antibacterial effect against Gram-negative and Gram-positive strains, respectively, with this activity being higher among Gram-positive strains. The G3Cs showed antibiofilm activity against Gram-negative species at concentrations similar or one to four folds higher than the corresponding MICs. Combination of G3Cs with colistin showed a potential synergistic antibacterial effect reducing concentrations and toxicity of both agents. The antimicrobial and antibiofilm activity, the synergistic effect when combined with colistin and the in vitro toxicity suggest that G3Cs would provide a new therapeutic alternative against multidrug-resistant bacteria from veterinary origin

Modern Synthetic Methods for the Stereoselective Construction of 1,3-Dienes

The 1,3-butadiene motif is widely found in many natural products and drug candidates with relevant biological activities. Moreover, dienes are important targets for synthetic chemists, due to their ability to give access to a wide range of functional group transformations, including a broad range of C-C bond-forming processes. Therefore, the stereoselective preparation of dienes have attracted much attention over the past decades, and the search for new synthetic protocols continues unabated. The aim of this review is to give an overview of the diverse methodologies that have emerged in the last decade, with a focus on the synthetic processes that meet the requirements of efficiency and sustainability of modern organic chemistry

Synthesis of Spironucleosides: Past and Future Perspectives

Spironucleosides are a type of conformationally restricted nucleoside analogs in which the anomeric carbon belongs simultaneously to the sugar moiety and to the base unit. This locks the nucleic base in a specific orientation around the N-glycosidic bond, imposing restrictions on the flexibility of the sugar moiety. Anomeric spiro-functionalized nucleosides have gained considerable importance with the discovery of hydantocidin, a natural spironucleoside isolated from fermentation broths of Streptomyces hygroscopicus which exhibits potent herbicidal activity. The biological activity of hydantocidin has prompted considerable synthetic interest in this nucleoside and also in a variety of analogues, since important pharmaceutical leads can be found among modified nucleoside analogues. We present here an overview of the most important advances in the synthesis of spironucleosides

Stereoselective synthesis of carbohydrate-derived N-Sulfonyl aziridines

A novel reaction of iodomethyllithium with a variety of sugar-derived N-sulfinyl imines, under very mild conditions, is described. N-Sulfonyl aziridines were easily obtained in high yields and in moderate to good stereoselectivities through an addition/oxidation protocol. A mechanism is proposed that is supported by the results of X-ray diffraction studies. © Georg Thieme Verlag Stuttgart · New York.We appreciate financial support from the Spanish Ministerio de Economía y Competitividad (CTQ2010-14959, MAT2006-01997, MAT2010-15094 and Factoría de Cristalización Consolider Ingenio 2010), Fundação para a Ciência e a Tecnologia (project PEst-C/QUI/UI0062/2011) and FEDER funding. C.C.F. and N.A. thank MICINN for a Juan de la Cierva contract and FICYT for a ­predoctoral fellowship, respectively. R.S. thanks the FCT for an ­‘Investigador Auxiliar’ position.Peer Reviewe

Polyhydroxylated Cyclopentane β-Amino Acids Derived from d-Mannose and d-Galactose: Synthesis and Protocol for Incorporation into Peptides

A stereoselective synthesis of polyhydroxylated cyclopentane β-amino acids from hexoses is reported. The reaction sequence comprises, as key steps, ring-closing metathesis of a polysubstituted diene intermediate followed by the stereoselective aza-Michael functionalization of the resulting cyclopent-1-ene-1-carboxylic acid ester. Examples of synthesis of polysubstituted 2-aminocyclopentanecarboxylic acid derivatives starting from protected d-mannose and d-galactose are presented. A general protocol for the incorporation of these highly functionalized alicyclic β-amino acids into peptides is also reported.This work has received financial support from the European Union (European Regional Development Fund - ERDF), the Spanish Ministerio de Economía y Competitividad (SAF2014-60138-R), the CIBER BBN (CB/06/01/0074), the Xunta de Galicia (Centro Singular de Investigación de Galicia accreditation 2019–2022, ED431G 2019/03; and grants ED431C 2018/30 and ED431C 2018/04), the Generalitat de Catalunya (2017-SGR-1439), and the Galchimia S.A. (Spain). R.B. and F.F. thank the Ministerio de Educación, Cultura y Deporte and the Ministerio de Educación y Ciencia, respectively, for FPU fellowships.Peer reviewe