He got away from Sauce because he fulfilled his goal with Naruto he ran because Mini Juubi (Cloaked Guy) told Shin he was no match and Kamui'd them both away.
In Sasuke's case he could of easily solo glanced Shin and kept him there with Naruto he could of put some effort in and captured Shin but that would of have to been before Juubi came in with Kamui lol.
Well, you sound a bit salty. Here let me tell you what happaned..
He ran away from Sasuke because he was shocked to see a random kid with a Sharingan. This shows he lost his cool.
He ran away from Naruto because he had S/T ninjutsu. Appearantly Naruto isn't fast enough to blitz the kid before he could complete his transportation.
Both failed miserably. Lord Itachi would've burned the kid to crips before he could complete his transportation in Naruto's case.
In Sasuke's case, well Lord Itachi can kill Uchiha's like flies. Eye contact-Tsukuyomi gg.