Introduction of Protecting Groups

 

Protecting Groups

Protecting groups 

Introduction

PG is a molecular framework that is introduced onto a specific functional group (FG) in a poly-functional molecule to block its reactivity under reaction conditions needed to make modifications elsewhere in the molecule.

OR

are used in synthesis to temporarily mask the characteristic chemistry of a functional group because it interferes with another reaction.

Example

Deprotecting groups 

The group that are involved in the cleavage of side chain protecting group is called de-protecting groups

Protection

When chemical reaction is carried out selectively at one reactive site in a poly functional compound while the other reactive sites must be temporarily blocked. This is called protection

Deprotection

When we want that protecting group to remove after addition of specific reagent. We can get the original functional group back. This is called deprotection. 

Criteria for the good Protecting groups

A good protecting group should be

• easy to put on,
• easy to remove
• in high yielding reactions,
• inert to the conditions of the reaction required.

Types of Protecting Groups

There are different types of protecting groups

1. Alcohol Protecting Groups
2. Protecting Groups for Carbonyl (Aldehydes and Ketones)
3. Protection of amino groups
4. Protection of carboxylic groups