Chapter 24, Problem 39P

Interpretation Introduction

Interpretation:

Using curved arrows, a mechanism is to be written to show the formation of oxygen-stabilized carbocation from each of the glycosyl donor.

Concept introduction:

The sulfide acts as a good nucleophile on reaction with an electrophile and forms sulfonium salts.

In pyranose, the carbocation formed at anomeric carbon stabilized by delocalization of pi electrons on oxygen is called oxygen-stabilized carbocation.

Due to planarity, the group attacking the oxygen-stabilized carbocation may approach from either side of the ring and gives $\text{N-trimethylsilyl}$.

Trimethylsilyl trifluoromethanesulfonate or methyl trifluoromethanesulfonate can be used to convert the group or atom to a good leaving group in a substitution reaction.