How to set the background color on a disabled button by a converter?

I have a button which action can be take a lot of time. Is an async method, so in this way I don't block the UI, but also I would like to disabled the button to avoid the chance of execute another same action.

For that, I disabled the button and I change its background, to show that the action that is running is the action that I start when I click this button.

I have a converter, because in my View Model I have a bool property that set if the action has started or if the action has finished. To convert this bool to a background color I use a converter.

Well, the problem is that if I disabled the button, is not possible to set the background with the converter.

I would like to know how I can do this, disabled the button and change the backgrund with a converter.

My code in my view model

private async void componentesAsignar()
{

    Bussy = true; //need for the converter, to set the background
    MyActionStarted = true; //need to disabled the button

    await Task.Delay(10000); //the code that takes many time
}

My code in my view

<Button Content="MyAction" Height="23" Name="btnMyAction" Width="75"
    Background="{Binding MyActionStarted, Converter={StaticResource actionInProgressToColorConverter}}">

My converter

object IValueConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
    if(((bool)value) == false)
    {
        return "#FFDDDDDD";
    }
    else
    {
        return "#FF589FF3";
    }
}

I am usgin Visual Studio 2013 Community and .NET 4.5.1.

Thank so much.