This type of a synthesis challenge is what I like to call a “cute” problem when we take a molecule and “insert” a methylene (CH2) group somewhere in the chain. Of course, there’s no way you can easily insert a carbon in the middle of the chain. So, we have to come up with a series of steps that would allow us to add carbons and reassemble the same functional groups that we might’ve had in this molecule.
There are multiple different ways how we can approach this problem. The key here is to recognize that no matter what way you decide to go, you need to add a carbon to your molecule and you can only do it with one of the carbon-carbon bond formation reactions like a Grignard reaction or a Wittig reaction.
Reactions you’ll see in this synthesis are: