Surely is the first move, since playing anywhere else allows Black at to make two eyes.
Perhaps this diagram is almost needless? If , kills.
If connects, then cuts. The four Black stones at the corner has only two liberties...
But if ataris, then bingo, is a snapback.
This leaves Black with only one eye.
to does the job as well, but it is suboptimal. The sacrifice of is not neccessary here.
What about ? Next, a and b seems miai...
But solves the problem. Black suffers from double shortage of liberties yet again.