Diels Alder Synthesis Problem

[blazinfury]

How would one do such a Diels Alder rxn synthesis starting with 4 carbons or less to achieve the attached molecule as your end product? In these types of problems, where does one typically start (how do you where to put the double bond(s))? Thanks so much.

[UC]

The easiest way to start these is to look at the ring and what substituents are on it. You need to have a diene and a dieneophile. The dienophile contributes 2 carbons to the ring and is generally equipped with electron withdrawing groups. The diene contributes 4 carbons to the ring and usually has electron releasing groups on it.

 

The final product has one double bond, right between the double bonds on the diene. Hint hint: an enol ether would be a very good electron releasing group and might take care of where that double bond goes.

 

Since you have specific orientation for your substituents, you need to look at the cis principle and endo addition rule.

 

I have no idea how to use 4 carbons, but I see a very easy way to use 5.