Q.60. - Organic Chemistry

Question

Question: Devise a synthesis of each compound from the given starting material. You may use any other organic compounds or required inorganic reagents

Step-by-Step Solution

Answer

Answer

a. Aldol condensation of acetophenone followed by the reduction with a palladium catalyst forms the final product.

b. Robinson annulation of the given ketone and enone followed by reaction with a Gilman reagent gives the final product.

Step 1: Aldol condensation

Aldehydes or ketones, in the presence of a strong base, undergo condensation to form  $\mathit{\beta }$-hydroxy compounds. If ketones are used, the product formed is  -hydroxy ketone.

The condensation involves the formation of enolate from one compound and consequent attack of the enolate on another carbonyl.

This reaction is followed by dehydration to form an enone.

The condensation reaction is a vital part of organic synthesis because it forms a new C-C bond.

Step 2: Robinson annulation

Robinson annulation involves the reaction between a ketone and alkenone to form a cyclo hexenone.

The first stage of the reaction is a Michael addition that is followed by intramolecular aldol condensation.

Michael addition causes the formation of 1,5 dicarbonyl that undergoes aldol condensation.

These reactions also cause the formation of new C-C bonds from carbonyls and are, therefore, important in organic synthesis.

Step 3: Synthesis of the given compounds

a. Aldol condensation of acetophenone produces an enol that, on reduction with a palladium catalyst, forms the final product.

Synthesis of a

b. Robinson annulation of the given ketone and enone followed by reaction with a Gilman reagent gives the final product.

Synthesis of b