This could be an answer, but my original intention was to provide useful hints for you.
If I read correctly, you are trying to bind a single key to several keys presses. In your given example, you want to remap End to Ctrl+E (this is easier to understand).
The classic approach is to check your keycode using
xev and use X tool like
xmodmap to remap the keys, as explained in this answer on askubuntu.com. But this doesn't allow you to remap several keys, mentioned in the answer for this question.
The other approach is to use
xbindkeys to grab the keys and
xvkbd to send keys, whose answer was given to this post. However, this approach also has its own caveat which cause focus to lose, as mentioned by someone in the comment.
Actually, there is similar question being asked, to remap several key presses to another several key presses (which is one level harder than your request). Unfortunately, the answer has clearly mentioned that you can't achieve that with
xmodmap and suggesting to use
Some time ago, I was still using a two-button mouse (I know, quite old piece of hardware) and trying to emulate the mouse middle-click. Then, I discovered
xdotool which was able to emulate mouse clicks, as well as keyboard key presses.
My suggestion is, use
xdotool to emulate keyboard key press for End (this will give you a string of command). Then use this command to assign a custom shorcut Ctrl+E in Xfce4, which is found under Settings Manager > Keyboard > Application Shortcuts.
To build the command using
xdotool, you can refer to the documentation. I haven't used this tool for some time, so I can't give exact answer to your question. In my opinion, using
xdotool with Xfce4 Application Shortcuts is the best solution you can try on Debian Xfce.