Enols – Enolates, and the Aldol Condensation – Part 2 | Organic Chemistry 3

The Enols and Enolates are studied in this chapter: the halogenation of aldehydes and ketones, the 1,2- and 1,4-additions of organometallic reagents, the Michael addition, the Robinson annulation. This chapter is a continuation of chapter 8 – Organic Chemistry 2.

Halogenation of Aldehydes and Ketones

 


Mechanism:

Step 1: Enolization
 

 

Step 2: Halogen attack followed by deprotonation
 

1,2- and 1,4-Additions of Organometallic Reagents

 


RLi: 1,2-Addition
R2CuLi: 1,4-Addition
RMgBr: 1,2 or 1,4-Addition depending on reagent and substrate structure

Michael Addition

 


Mechanism:
 

 

Robinson Annulation

Robinson Annulation = Michael addition followed by an intramolecular aldol condensation.

 

 

Mechanism:

Step 1: Michael addition
 

 

Step 2: Intramolecular aldol condensation