[Rutherford]

How to solve this? In my attempt, I thought of a 1,3-dipolar addition, but I can't find a way to connect PhNCS with the hydrazide and I don't see how I should obtain the amine (which would convert to azide to participate in the 1,3 addition).

[TheUnassuming]

So to get the azide from the levulinic acid (ketal protected) you might want to think about utilizing a mitsunobu reaction.  It would take two steps from your protected acid to reach the azide by that method. 

Attaching the hydrazide acetate I think you might be able to do late stage (though perhaps not in that exact form initially).   

[Benzene]

I know how how the core heterocycle is created.

Then once you create this ring the S acts as a nucleophile and the lone pair on the nitrogen will create the second double bond with the carbon

[TheUnassuming]

That looks reasonable for the cyclization to make the product if you use the ketal protected levulinic hydrazide instead of the acetyl version drawn. 

[Rutherford]

Thanks for the responses. That'a a far better way as no azides are needed. Now it gets even trickier. What synthons will be present here?

[Rutherford]

Anyone has a suggestion?