From time to time, we need to selectively redirect the browser to another location as a 
result of an AJAX action. Just returning RedirectResult won’t do the trick (even if we 
are used to similar functionality in ASP.NET AJAX in combination with WebForms ). Here 
is a very simple RedirectResult thet will be appropriate in those scenarios:

    public class AjaxRedirectResult : RedirectResult
    {
        public AjaxRedirectResult(string url): base(url){}
        public override void ExecuteResult(ControllerContext context)
        {
            if (context.RequestContext.HttpContext.Request.IsAjaxRequest())
            {
                JavaScriptResult result = new JavaScriptResult()
                {
                    Script = String.Format("window.location='{0}';",
			UrlHelper.GenerateContentUrl(Url, context.HttpContext)) 
                };
                result.ExecuteResult(context);
            }
            else
                base.ExecuteResult(context);
        }
    }