A convenient, efficient and fast acetylation combining clays and ultrasound irradiation is described. Some molecules from nature or synthetic source, i.e., D-glucose, glycerol, D-mannitol and 1,2,3-triazolic derivatives such as N-glucosyl sugars and 2-substituted 1,4-naphthoquinone structures were acetylated. This kind of chemistry may be classified as eco-friendly because the reactions take a short time and the catalyst is reusable.

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Carbohydrates are the most abundant biomolecules that play crucial roles in many biological processes. In carbohydrate chemistry, the S-glycoside is an organic molecule in which sugar is bound to another functional group via a glycosidic bond. In the last few years, considerable progress has been made in the synthesis and applications of S-glycosides. Despite their challenging chemistry, S-glycosides play a pivotal role the development of the development of chemistry of biologically active molecules. This review, we report the natural occurrences, biosynthesis, different synthetic methodologies, proposed mechanisms and applications of S-glycosides. Os carboidratos são as biomoléculas mais abundantes que desempenham papéis fundamentais em muitos processos biológicos. Na química dos carboidratos, o S-glicosídeo é uma molécula orgânica na qual o açúcar é ligado a outro grupo funcional por meio de uma ligação glicosídica. Nos últimos anos, houve um avanço na síntese e aplicações de S-glicosídeos. Apesar de sua química desafiadora, os S-glicosídeos desempenham papel fundamental no desenvolvimento da química de moléculas biologicamente ativas. Nesta revisão, relatamos as ocorrências naturais, biossíntese, diferentes metodologias sintéticas, mecanismos propostos e aplicações de S-glicosídeos.

RECENT ADVANCES IN CHEMISTRY OF AMINO SUGARS: OCCURRENCE, BIOSYNTHESIS, SYNTHESIS AND APPLICATION. Amino sugars are chemical compounds that have a sugar backbone, in which one of the hydroxyl groups is replaced by an amino group. Derivatives of amine-containing sugars, such as N-acetylglucosamine, are also considered amino sugars. The synthetic introduction of amino functionalities in a regio-and stereoselective manner ontosugar scaffolds represents a substantial challenge. Most of the modern methods for the preparation of 1-, 2-and 3-amino sugars are those starting from glycals, 2,3-unsaturated O-glycosides epoxy-sugars, keto-sugars among others. This review summarizes recent developments in the current state of knowledge concerning the occurrence, biosynthesis, synthesis and application of amino sugars.

DEVELOPMENT IN GLYCOSYLATION METHODS: A KEY TO ACCESS ITS APPLICATIONS IN THE SYNTHESIS OF BIOACTIVE MOLECULES. Glycosylation reaction is an important class of reactions in organic chemistry, and the development of the method contributes to the synthesis of many biologically active compounds containing various glycoside bonds. Is arguably the most important, albeit challenging, reaction in the field of carbohydrate chemistry. Examples of the products of glycosylation reactions are glycoproteins, glycolipids, glycosaminoglycans, oligosaccharides, and polysaccharides. Glycosylation types are classified according to the identity of the atom which binds the carbohydrate chain, i.e. C-linked, N-linked, O-linked or S-linked. In this short review, recent reports of the main glycosylation methods, basic mechanisms, factors influencing the stereoselectivity and their applications in the synthesis of bioactive molecules are described.