how can i evolve vowel harmony into my conlang?

my goals for these sound changes is to get a front-back harmony system with a trojan vowel - more explained later on - out of a simple four-way set of un-harmonized vowels.

my current inventory consists of /i o u a/ and i want to evolve it to where it goes to /a ɑ i e o y u/ and then a & ɑ merge into a trojan vowel and o be a transparent

would it be changes like
a > ɑ / {o,u}C_
o > e / {a,i}C_
u > y / {a,i}C_

so for example, ku-ta > ku-tɑ; ta-ro > ta-re? is that basically how it works?

edit: sorry for not saying this before but my protolanguage is entirely CV(C) where the final C is only word-final