Reactions of Hemiacetals or Hemiketals with Alcohols

Reaction of D-glucose in methanol proceeds through the a- and P-furanoside forms, through the P-pyranoside form, ultimately to the a-pyranoside form, which becomes the predominant product. 

There is a reverse anomeric effect that occurs when an atom from the aglycone attached to C-1 has a positive or partial positive charge [38]. This is evidenced by pyridinium glycosides or glycosides containing a carbonyl group attached to the anomeric carbon. 

---