[PharmaStud.]

Hello,

I'm working on 5-fluorouracil and its impurities for a presentation. But I can't find the origin of two of its impurities: 5-methoxyuracil and 2-ethoxy-5-fluorouracil. I have a theory for 5-methoxyuracil but I'm not sure. And for 2-ethoxy-5-fluorouracil I'm still lost, I don't know where it comes from, what reaction it could come from.

I've attached the photo of the mechanism of synthesis of 5-fluorouracil and a reaction which could give us 5-methoxyuracil but I'm not sure about it.

It would help me a lot, if someone could guide me in the right direction

Thanks in advance,
Have a nice day !