Chapter 14.12, Problem 27ATS

Interpretation Introduction

Interpretation:

The synthesis for the given compound has to be done.

Concept Introduction:

Epoxides are obtained by the conversion of Alkene using Peroxy acids and Halohydrins

Epoxides from Peroxy acids:

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

Ring opening reactions occur when an Epoxide is attacked by strong nucleophile. The mechanism of transformation generally occurs in two steps as nucleophilic attack and proton transfer.

The reactions of Epoxides with strong nucleophiles requires a strong driving force that helps in the removal of ring strain associated with the three-memebered ring of an Epoxide. These ring opening reactions also occur under acidic conditions.

The mechanism of acid-catalyzed ring opening of an Epoxide occurs in two steps.

In first step, the protonation of Epoxide occurs.

In second step, the attack of nucleophile occurs in the protonated Epoxide by ${\text{S}}_{\text{N}}\text{2}$ process.

The important features of ring opening reactions are regiochemistry and stereochemistry.

1. 1) Regiochemistry: The regiochemistry depends on the nature of Epoxide when the starting Epoxide is unsymmetrical.
2. 2) Stereochemistry: Inversion of configuration is observed when nucleophilic attack is seen at less hindered primary position if one position is primary and other is secondary. This steric effect is also expected from ${\text{S}}_{\text{N}}\text{2}$ process.