Application of Ara-β-(1 → 2)-Ara diarabinofuranosides with O-TBDPS protective groups in the synthesis of the tetra- and dodecaarabinofuranosides - fragments of mycobacterial polysaccharides.

Abstract

The synthesis of Ara-β-(1 → 2)-Ara glycosyl donor containing TBDPS groups starting from the corresponding glycoside with 4-(3-azidopropoxy)phenyl aglycone was performed in high yield. The obtained glycosyl donor was successfully used in the stereocontrolled synthesis of 4-(2-azidoethoxy)phenyl glycosides of linear β-(1 → 2)-, α-(1 → 5)-tetra- and branched β-(1 → 2)-, α-(1 → 3)-, α-(1 → 5)-linked dodecaarabinofuranosides related to the fragments of mycobacterial polysaccharides. These compounds are valuable for the preparation of conjugates that can be used as antigens in the diagnosis of mycobacterial infections. The synthesis of Ara-β-(1 → 2)-Ara glycosyl donor containing TBDPS groups starting from 4-(2-chloropropoxy)phenyl glycoside was found to be less efficient due to side reactions in course of manipulations with protective groups. Thus, during the treatment with TBAF, 4-(3-chloropropoxy)phenyl aglycone was partially converted to the product of substitution (4-(3-fluoropropoxy)phenyl) and elimination (4-allyloxyphenyl). In the course of silylation (TBDPS-Cl/imidazole), the formation of 4-[3-(imidazole-1-yl)propoxy]phenyl derivative was observed.