Methyl tetra - 0-methyl- ?-D- glucopyranoside is stereoselectively prepared
from tetramethyl-D- glucopyranose by using (MeI+NaH) in toluene (86%) or
cyclohexane (85%), while its ?- isomer is best synthesized in hexamethyl
phosphoramide (64%). Similarly, methyl tetra-o-methyl-?- D-mannopyranoside is
synthesized in cyclohexane (80%), while its ?- isomer is predominantly prepared
by (MeI+n-BuLi) in cyclohexane (98%). The ?-and ?- isomers of these glycosides
were identified and quantified by G.C