Ignore everything in folder except specific file

help

#1

I'd like to add a very large directory into my local ownCloud share folder but only sync 1 specific file and ignore everything else (all other files & subfolders recursively).

Is there some pattern which can do this?
I was thinking about something like sync/chrome/!(Bookmarks) to ignore everything in the directory sync/chrome except the file sync/chrome/Bookmarks.

The use case is that I'd like to put my complete Chrome profile into the ownCloud share but only sync the bookmarks file...