Résumé
Glycosyl beta-bromo-alpha-ketonitriles can be conveniently accessed through a versatile reaction of easily available dialdoses with potassium dibromoacetonitrile anion in isopropanol. They proved to be very useful intermediates in the direct preparation of new glycoamidoesters and glycothioesters. The synthesis of the title compounds involves coupling of glycosyl beta-bromo-alpha-ketonitriles intermediates with suitably protected amino acid esters and 1-propanethiol, respectively. The coupling reaction proceeded smoothly at rt affording the targeted products in good yields and with moderate diastereoselectivities. The route presented here constitutes an important synthetic potential for the rapid preparation of new glycoamidoesters and glycothioesters that can find application as useful building blocks in the construction of more complex glycopeptides.