Stereoselective synthesis of a fragment of mycobacterial arabinan

Strategies for the stereoselective synthesis of mycobacterial arabinan were explored. Arabinofuranosyl donors with various protective groups were screened in terms of suitability for beta-( 1,2- cis)- selective glycosylation. The protective group was found to affect the stereoselectivity of arabinofuranosylation. beta-Selectivity was drastically enhanced by using donors protected with 3,5- TIDPS, possibly due to conformational constraints on the furanose ring. Synthesis of heptaarabinofuranoside was then performed to demonstrate the practicality of this methodology.