How to stop Rotation

To rotate an object I use:

transform.Rotate(Vector3.forward * -1 * mydir * 45 * Time.deltaTime);

in Update(). This works most of the time....

I need to stop rotation when it is pointing towards another object. To do this, I check if the Angle is less than a certain amount of degrees.

The problem I am having is that since Update() is called every frame, there is a chance I will skip over the time where we met the conditions to stop. I wanted to avoid using Slerp.

I'd like to know if there is a way to stop the rotation at the right time, without slowing down the rotation rate too much.

Don't just incessantly run that code in Update(). Use an if statement and only rotate like that if you're within your constraints. Otherwise, rotate only as much as it takes to get to your desired rotation.