How to move an object by a certain angle over a period of time

From the image below, I know points `A` and `B` and would like to move `B` by e degrees (around A with in a circle of radius AB) to a point C which I don't know over a period of time, say 2 seconds. How can this be done, preferably with a coroutine?

 

The easiest way would be to just put an object at point A, make the object at point B a child of A, and then rotate A by e degrees over those 2 seconds.

 

I will be moving an object around several circles with different centres, so I'm not sure if this would be an ideal solution. I think a more general form of just using a Vector3 position as a centre would be more appropriate in my case. Also I don't know now how to move an object around a circle.