@(Html.Kendo().Button()
                    .Name("btnSubmit")
                    .HtmlAttributes(new { type = "button", title= "Report1", url = "/Controller1/Method1/"  })
                    .Icon("k-icon k-i-file-txt")
                    .Content("View Details")
                    .Events(e => e.Click("ShowDetails"))

)

function ShowDetails() {
    var URL = this.element.attr("url")
    $('#win_wnd_title').text(this.element.attr("title"));
    $.ajax(
        {
            url: URL,
            type: 'post',
            dataType: "html",
            data: ?
            contentType: 'application/json; charset=utf-8',
            success: function (result) {
                var dialog = $("#win").data("kendoWindow");
                $("#dataWin").html(result);
                dialog.open();
                showLoaderPopup();
            }
        })
}

If (flag == 1)
{
   var myData =  JSON.stringify({ ID: id, Amount: amount, Desc: desc });
}
else
{
   var myData = null
}

$.ajax(
   {
      .
      .
      .
      data: myData
   }
)

Button()
  .Name("btnSubmit")
  .HtmlAttributes(new { type = "button", title= "Report1", url = "/Controller1/Method1/", sendData = "true" })
  .Icon("k-icon k-i-file-txt")
  .Content("View Details")
  .Events(e => e.Click("ShowDetails"))
)

function ShowDetails() {
    var URL = $(sender).data('url');
    var myData = null;

    if($(sender).data('sendData') == "true")
    {
        myData = JSON.stringify({ ID: id, Amount: amount, Desc: desc });
    }

    $.ajax(
    {
        ...

        data: myData
        success: function (result) {
        ...
        }
    })