As far as I am concerned, from unsaturated primary/secondary amines (enamines) we obtain imines, like we do obtain carbonyls from enols, by tautomerism. For tertiary enamines, we have a corresponding iminium ion by a similar process (even though I don't think it works in the same direction). Do we have anything like this for an ether? (which looks to me pretty similar to a tertiary amine as reactivity, as far as I understand).
P.S. I'm looking for the structure R-(O+)=R'