Quaternion Rotation Lerp with IEnumerator

RotateLerp.cs

// rotate target transform from Quaternion A to Quaternion B, within duration

// to call
StartCoroutine(RotateLerp(transform, Quaternion.Euler(0,90,0)));


IEnumerator RotateLerp(Transform target, Quaternion endRot)
{
    float duration = 1.5f;
    var startRot = target.rotation; // current rotation
    for (float timer = 0; timer < duration; timer += Time.deltaTime)
    {
        target.rotation = Quaternion.Slerp(startRot, endRot, timer / duration);
        yield return 0;
    }
}