Q.59. - Organic Chemistry

Question

Question: What allylic alcohol and DET isomer are needed to make each chiral epoxide using a sharpless asymmetric epoxidation reaction?

Step-by-Step Solution

Answer

Answer

a.(-) DET and allylic alcohol is:

b. (-) DET and allylic alcohol is:

c. (+) DET and allylic alcohol is:

Step 1: Sharpless asymmetric epoxidation reaction:

The Sharpless reaction is the oxidation of alkenes by asymmetric epoxidation. The reaction makes use of titanium tetraperoxide. Sharpless and his coworker summarized Sharpless's reaction by adding a chiral ligand, DET, which is capable of making the reaction asymmetric.

Step 2: Example of Sharpless asymmetric epoxidation

An example for Sharpless asymmetric epoxidation is given below:

Example for Sharpless asymmetric epoxidation

Step 3: The DET isomer and allylic alcohol used for the preparation of each chiral epoxide

The alkene acts as a nucleophile to attack the equatorial oxygen atom of the peroxide, from alkenes to lower face allylic alcohol, and their epoxides are valuable building blocks in organic synthesis. The DET isomer and allylic alcohol used for the preparation of each chiral epoxide can be thus represented:

Representation of asymmetric epoxidation reaction of a.

Representation of asymmetric epoxidation reaction of b.

Representation of asymmetric epoxidation reaction of c.