I don't think that's possible.

You could make a bind that turns up your sensitivity to let you turn though.

Go into console and put in everything that is bolded.

Bind "F" +right (you can change the key binding to whatever is easier for you and you can change to turn left if you want.)

Then put in,

cl_yawspeed 1500 (you can increase the speed more if you want.)

EDIT: Apparently cl_yawspeed doesn't work on match making servers for CSGO, you can make a macro/script if you want to do a perfect 180, though to be honest it's pointless because chances are if they're behind you, you're more than likely dead, unless someone's aim is just so atrocious and can't put you down when behind you.

It should be possible but I see no point in this if you can just simply turn 180 with a swipe of your mouse.

I have seen a couple people make multiscripts for the game that include this feature. I forgot where they are but I guess a simple google search will do. Scripts are banable I think tho in overwatch so watch out