Issue With Rotation on Key Press

Hi There,

I'm trying to make a 3D cube rotate to another face based on the currently visible face (in 2D view). I can go from red -> neutral -> green and in reverse, and red -> green, however trying to go from green - > red does not value. On entering the green face, it's X rotation becomes -5.008956e-06 and it's Y and Z become 180. Interestingly the co-routine still runs, changing the current face at end.

 using UnityEngine;
     using System.Collections;
      
     public class RotationScript : MonoBehaviour {
      
         public enum gameColors{Red,Green,Neutral};
         
         public gameColors charColor;
         
         public float redRotation = 0.0f;
         public float greenRotation = 180.0f;
         public float neutralRotation = 90.0f;
         
         // Use this for initialization
         void Start () {
         
         }
         
         IEnumerator RotateCube(Quaternion rotationTarget, float rotateTime, gameColors targetColor)
         {
             float elapsedTime = 0.0f;
             
             Quaternion startingRotation = transform.rotation;
             
             while (elapsedTime < rotateTime)
             {
                 elapsedTime += Time.deltaTime;
                 
                 transform.rotation = Quaternion.Slerp(startingRotation,rotationTarget, (elapsedTime / rotateTime));
                 
                 yield return new WaitForEndOfFrame();
             }
             
             charColor = targetColor;
         }
         
         // Update is called once per frame
         void Update () {
         
             if (Input.GetKeyDown(KeyCode.W))
             {
                 if (charColor == gameColors.Red)
                 {
                     Quaternion tarRotate = Quaternion.Euler(new Vector3(neutralRotation,0.0f,0.0f));
                     StartCoroutine(RotateCube(tarRotate,1.0f,gameColors.Neutral));
                 }
                 if (charColor == gameColors.Neutral)
                 {
                     Quaternion tarRotate = Quaternion.Euler(new Vector3(greenRotation,0.0f,0.0f));
                     StartCoroutine(RotateCube(tarRotate,1.0f,gameColors.Green));    
                 }
             }
             
             if (Input.GetKeyDown(KeyCode.S))
             {
                 if (charColor == gameColors.Neutral)
                 {
                     Quaternion tarRotate = Quaternion.Euler(new Vector3(redRotation, 0.0f,0.0f));
                     StartCoroutine(RotateCube(tarRotate,1.0f,gameColors.Red));
                 }
                 if (charColor == gameColors.Green)
                 {
                     Quaternion tarRotate = Quaternion.Euler(new Vector3(neutralRotation,0.0f,0.0f));
                     StartCoroutine(RotateCube(tarRotate,1.0f,gameColors.Neutral));
                 }
             }
             
             if (Input.GetKeyDown(KeyCode.X))
             {
                 if (charColor == gameColors.Red)
                 {
                     Quaternion tarRoate = Quaternion.Euler(new Vector3(greenRotation,0.0f,0.0f));
                     StartCoroutine(RotateCube(tarRoate, 1.0f,gameColors.Green));
                 }
                 
                 if (charColor == gameColors.Green)
                 {
                     Quaternion tarRotate = Quaternion.Euler(new Vector3(greenRotation,0.0f,0.0f));
                     StartCoroutine(RotateCube(tarRotate, 1.0f,gameColors.Red));
                     Debug.Log("hello");
                 }
             }
         }
     }

I'm getting the same values pre-baking the rotations with animations, and using iTween. Why is the cube not rotating for the green -> red transition, and why is it reporting such an unusual value? I assume the green position would be 180 degrees Any help would be appreciated!