Chapter 23, Problem 23.62SP

(a)

Interpretation Introduction

Interpretation:

The information regarding the steric hindrance in TIPDS around silicon atoms by isopropyl groups is given. The given $\text{OH}$ group that will first react with TIPDS chloride and the product formed after with the TIPDS group on one oxygen atom is to be stated.

Concept introduction:

Protecting group is a species that undergoes chemical modification so that chemoselectivity can be introduced in the chemical reaction.

(b)

Interpretation Introduction

Interpretation:

The information regarding the approach of TIPDS attached with one of the oxygen towards the other oxygen is given. The final product formed after the protection of two oxygen groups is to be stated.

Concept introduction:

Protecting group is a species that undergoes chemical modification so that chemoselectivity can be introduced in the chemical reaction.

(c)

Interpretation Introduction

Interpretation:

The information regarding reaction of unprotected hydroxyl group without affecting the protected oxygens is given. The product formed after the protected nucleoside from (b) is treated with tosyl chloride and pyridine, followed by $\text{NaBr}$, ending with deprotection with ${\text{Bu}}_4\text{NF}$ is to be stated.

Concept introduction:

Protecting group is a species that undergoes chemical modification so that chemoselectivity can be introduced in the chemical reaction.