How Can Isoxazole Be Synthesized from Furoxan and Phenylacetylene?

[Natalie456]

Homework Statement

Provide a mechanism for the conversion of the furoxan with phenylacetylene and DMF to create the isoxazole.

Relevant Equations

1,3 - dipolar cycloaddition?

I'm having difficulties uploading my work to this system at the moment, but I have currently attempted 1,3-cycloaddition between the furoxan and phenylacetylene. However, unless a sigmatropic rearrangement occurs (which, as far as I can conclude, leads to instability with charges), this places the methyl and phenyl groups in the incorrect places. Is there a better way to, perhaps, go about this mechanism? Thank you.

 

[TeethWhitener]

Homework Statement:: Provide a mechanism for the conversion of the furoxan with phenylacetylene and DMF to create the isoxazole.
Relevant Equations:: 1,3 - dipolar cycloaddition?

I'm having difficulties uploading my work to this system at the moment

Yeah unfortunately there aren't really any good options.

The only thing I can think to help you out with your question is that unsymmetrically substituted furoxans can sometimes isomerize between the two forms:

This form gets you closer with 1,3-dipolar cycloaddition.

Edit: here's a reference to furoxan isomerization:
https://link.springer.com/article/10.1007/BF00519947

Further edit: obviously the tetravalent nitrogens have a +1 formal charge. Dunno why the drawing program didn't take care of that automatically.