Q.27. - Organic Chemistry

Question

Question: What starting materials are needed to synthesize each compound by a Robinson annulation?

Step-by-Step Solution

Answer

Answer

                    Starting materials of c.

Step 1: Locate the cyclohex-2-enone ring and re-draw the target molecule if necessary

The α,β-unsaturated carbonyl system in such a manner that the carbonyl group comes on the left. The target compound may have to be flipped or rotated, but the bonds must remain unchanged. 

Step 2: Break the cyclohex-2-enone ring into two components

Break the C=C bond such that one half of it becomes the carbonyl group of the enolate compound; while the other half remains the same. 

Break the bond between the $\mathit{\beta }$ -carbon and the carbon next to it.

Step 3: Compounds needed for Robinson Annulation

a. The compound is rotated to achieve the desired position of the molecule per the Robinson Annulation reaction method. The bonds are cleaved to obtain the two reactants.

b. The compound is rotated to achieve the desired position of the molecule per the Robinson Annulation reaction method. The bonds are cleaved to obtain the two reactants.

c. The compound is flipped to achieve the desired position of the molecule per the Robinson Annulation reaction method. The bonds are cleaved to obtain the two reactants.