This works, as long as the folder hierarchy depth is always the same. If not, you'll have to get more complex & use TOKENCOUNT too.
token(token("c-Drive\\Files\\Data\\Claims\\Current Load\\31 Dec 2012.xls","\\",6),".",1)
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.