Chapter 16.4, Problem 8ATS

Interpretation Introduction

Interpretation:

The structure of epoxides $\text{2}\text{and}\text{3}$ and the mechanism for the formation of $\text{4}$ have to be identified.

Concept Introduction:

Epoxides from Peroxy acids:

The commonly used Peroxy acids are meta-Chloroperoxybenzoic acid (mCPBA) and Peroxyacetic acid. This process is stereospecific.

  

Ring-opening of epoxide: The epoxide ring is highly strain and readily undergoes reaction with strong nucleophile result in the ring-opening reaction.

Acid-catalyzed ring-opening of epoxide: The epoxide ring is protonated and the nucleophile attack depends on the electronic or steric effect (nature of epoxide).

Regiochemistry: when the epoxide is unsymmetrical, the nucleophile attack at the more substituted position of the protonated epoxide ring.

Stereochemistry: when the nucleophile attack takes place at chiral center, an inversion of configuration is obtained.