Async and await asynchronous in C#winform

1 buttons, 2 textbox, the following can be correctly asynchronous, the form will not die, TextBox2 will first have results, TextBox1 again have the results

Private async void Button1_Click (object sender, EventArgs e) {
Does ();
TextBox2.Text = "1";
}


Private task<string> DoWork ()
{
Return Task.run (() =>
{
Thread.Sleep (4000);
Return "do with work!";
}
);
}
Private async void Does ()
{
String text = await DoWork ();
TextBox1.Text = Text;

}

If you change the button event to the following, the form will not die, but it will not execute asynchronously

   private async void Button1_Click (object sender, EventArgs e)         {
  &NB Sp         TextBox2.Text =await DoWork ()
            TextBox2.Text = "1";
       }