In a thesis, is it appropriate to allude to results obtained later on?

Is it appropriate to allude to results obtained later on?

Yes, please not only "allude" to later results, but make it absolutely clear at any point of your thesis what all the components of your argument are. You can, and sometimes should, defer the explanation of those components to a later part of your thesis. Just don't make your reader think "Huh? Something is missing here".

If you feel it is too much to ask your readers to accept a statement until it is explained in more detail, you can provide a very short and abstract version earlier. But this "preview" should only serve the purpose of making the reader aware of a part of the argument that will be explained later on; it should not be a duplicate explanation. (This could be just one or two sentences if possible, but two or three paragraphs at most and only if necessary.)

A thesis is not a suspense story. A crime novel aims for surprising plot twist; a thesis aims for a natural flow of the argument. If your readers are surprised at any point, your writing is not consistent enough.

This is also why in the standard format of research papers in most disciplines, the last part of the introduction is an outline of the entire argument.