I did some more research in this and a found a "illegal" (means, not by Adobe supported way) to change the keyboard shortcuts. http://digital-photography-howto.com/guide-to-customizing-keyboard-shortcuts-in-adobe-photoshop-lightroom/
I took his standard template file and changed the shortcuts for rotating in the library module to "<" and "Shift+<" (which is > on a german keyboard), so I have a logic way now to rotate the images.
Should work on Macs too, just do a google search for "TranslatedStrings.txt" and it will give plenty of information.
Hope it works well for you as it works for me.
Danke für die Grüße, Larry, Schöne Grüße auch für Dich, hoffe Du hast einen schönen Sonntag!