B(C 6 F 5 ) 3 -Catalyzed Stereoselective 1,2- cis Arabinofuranosylation with a Conformationally Constrained Donor.

Compared with stereoselective glycosylation methods mainly addressed on the preparation of pyranose glycosides, the furanosylation has been more limited, especially for the 1,2- cis arabinofuranosylation. Herein, we report a novel stereoselective 1,2- cis -arabinofuranosylation strategy using a conformationally restricted 3,5- O -xylylene-protected arabinofuranosyl donor on activation with B(C 6 F 5 ) 3 for desired targets in moderate to excellent yields and β-stereoselectivity. The effectiveness of the 1,2- cis -arabinofuranosylation strategy was demonstrated successfully with various acceptors, including carbohydrate alcohols.