Why doesn't Sasuke use Shadow clones?
Can Sasuke use the Shadow Clone Justu? Sure he can! However, he chooses not to because he does not want to associate himself with using Naruto's signature justu, which he sees as Naruto's weakness and coping method to his loneliness.
Shadow Clone Technique

Trivia
Due to Naruto's extensive usage of this technique, Sasuke sees it as a symbolic way for Naruto to avoid loneliness

This is referencing the manga, Chapter 696

In addition, there is a scene in the anime (which I can't vouch for being in the manga or not) during Sasuke's training where Orochimaru has him slay 1,000 un-named ninjas. Sasuke sees himself strong enough to not even need the help of Shadow Clones