[MichaelWestin]

Professor asked for the mechanism to combine 2 Benzaldehydes, Acetone (propanone) and malonic ester. That's it, and it seems pretty vague. I have no idea where to begin!

[MissPhosgene]

Can you make an acetal?

[MichaelWestin]

I guess so... thats all the question says. 

[MissPhosgene]

Yeah, that is really vague and confusing. Double aldol reaction with the malonic ester and benzaldehydes I suppose. Acetone to make the acetal....  decarboxylate under with basic conditions for ester hydrolysis?

Very very ambiguous question... there are lots of ways to combine the three... I assume you are in second semester ochem? The aldol, acetal seems to make the most sense from what I remember was covered when I took it.   

[Doc Oc]

That is way too ambiguous to have a single answer, but the first thing I thought of was a double aldol between the acetone and benzaldehyde, so you'd have a symmetric ketone intermediate.  Then addition of the malonic ester would lead to addition to the ketone and decarboxylation would ultimately give the acid.

Again, there's no way to know the correct answer without more information.

[MichaelWestin]

So here is the rest of it...  it comes together to form the attached picture. How would the mechanism for that reaction occur?

Thanks :-)