Are there any current rocket systems that go to the Karman line with just 1 stage without boosters? Recent Rockets like the Falcon 9 separate at 80 km. New Shepard launches recently touched 100 km but it's unclear if the rocket staging will occur at such a altitude. Old and big rockets like Soyuz and Ariane separate boosters at around 50 km but separate at much higher altitudes of 150+km.
It depends on your definition of a stage. Soyuz' boosters cut off and separate at ~40km, but the core stage cuts off well above the Karman line, around 175km altitude. This article refers to the boosters as "first stage" and the core as "second stage" despite the fact that the core starts burning at liftoff.
Single-stick launchers like Falcon 9 and Atlas V typically separate first stage at 60-80km altitude.