SN2Displacement of Carbohydrate Triflates by 9-Oximes of Erythromycin A and Of a Tylosin Derivative
摘要:
The preparation of 9-O-glycosyloxime derivatives of erythromycin A (1) and tylosin (2) is reported. Access to this new class of macrolides was achieved from (E)-9-oxime of erythromycin A (3) and 9-oxime of tylosin 20-(1,3-dithiane) (4), by successful displacement of triflates of suitably protected carbohydrates.
Ruthenium-Catalysed Epimerisation of Carbohydrate Alcohols as a Method to Determine the Equilibria for Epimer Interconversion in Hexopyranosides
作者:Clinton Ramstadius、Annika M. Träff、Patrik Krumlinde、Jan-E. Bäckvall、Ian Cumpstey
DOI:10.1002/ejoc.201100504
日期:2011.8
Ruthenium-catalysedepimerisation of secondary carbohydratealcohols was used to determine the thermodynamic equilibrium between non-anomeric epimers of partially protected glucose, mannose and allose derivatives. A cyclopentadienylruthenium catalyst was used to epimerise each of two pure epimeric alcohols in two separate experiments. The epimerisation reactions were run until the same ratio of epimers