Instance Object in circle

  float radius = 1f;

 int amountToSpawn;

 for (int i = 0; i < amountToSpawn; i++)

 {

     float angle = i * Mathf.PI*2f / amountToSpawn;

     Vector3 newPos = new Vector3(Mathf.Cos(angle)*radius, y, Mathf.Sin(angle)*radius);

     GameObject go = Instantiate(GameObject.CreatePrimitive(PrimitiveType.Cube), newPos, Quaternion.identity);

 }