[sun725]

I think it should be f and d but I'm not sure at all.  - Hope someone can help.

Thanks in advance.

[Babcock_Hall]

Would you mind providing your reasons?

[sun725]

We are using the Malonic Ester synthesis. We also have to add the elements of CH2COOH to the starting compound.
steps: a, c, d  ? Now when I'm looking at it again ... However, not sure at all. Hope you can provide me with more info?

[sun725]

Isn't there anyone who can answer me?

[Babcock_Hall]

Clearly your initial answer was wrong.  You need to add a total of four carbon atoms, for one thing.  Now let's take your second idea.  If this is going to be a malonic ester type synthesis, you will need to do something to your alcohol to make it an appropriate starting material.  What will you have to do, and how will you do it with these reagents?

[sun725]

And then we'll have to re-esterify. (d, f?)

[Babcock_Hall]

I don't understand your last response.  What is the nucleophile and what is the electrophile in the first step of a malonic ester synthesis?

[rolnor]

To decarboxylate you need to hydrolyse the malonic ester, then esterificate the resulting acid?

[Babcock_Hall]

rolnor,

It seems to me that the malonic ester should be connected to the rest of the molecule before one decarboxylates.  The OP needs to find a way to modify the alcohol first, unless I am missing something.

[rolnor]

Yes, you need SOCl2 first to make the alkylchloride then malonester.

[Babcock_Hall]

@OP, Now that you have been given some generous hints, this problem should be a snap.