Facile Cu(OTf)2-catalyzed preparation of per-O-acetylated hexopyranoses with stoichiometric acetic anhydride and sequential one-pot anomeric substitution to thioglycosides under solvent-free conditions.
Solvent-free per-O-acetylation of hexoses with a stoichiometric amount of acetic anhydride employing 0.03 mol % Cu(OTf)2 proceeded in high yields (90-99%) at room temperature to give exclusively pyranosyl products as an anomeric mixture, the alpha/beta ratio of which was dependent on the temperature and amount of catalyst used. Sequential anomeric substitution with p-thiocresol in the presence of BF3.etherate gave the thioglycosides, isolated exclusively or predominantly as one anomer in 66-75% yields.
Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan.
Cheng-An
CA
Tai
Suvarn S
SS
Kulkarni
Shang-Cheng
SC
Hung
D000089:Acetic Anhydrides / Q000737:chemistry*; D000107:Acetylation; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D003408:Cresols / Q000737:chemistry; D006601:Hexoses / Q000138:chemical synthesis*; D008698:Mesylates / Q000737:chemistry*; D009904:Optical Rotation; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism; D013865:Thioglycosides / Q000138:chemical synthesis*
D000089:Acetic Anhydrides; D003408:Cresols; D006601:Hexoses; D008698:Mesylates; D012997:Solvents; D013865:Thioglycosides; C031800:acetic anhydride; D003300:Copper; C012077:trifluoromethanesulfonic acid