import re
files = ['C:\\PATH\\PATH\\PATH\\thing1.xlsx', 'C:\\PATH\\PATH\\PATH\\PATH\\thing2.xlsx']
pattern = re.compile(r'\\([^\\]+)\.xlsx')
for x in files:
matches = pattern.findall(x)
print(matches)
aW1wb3J0IHJlCmZpbGVzID0gWydDOlxcUEFUSFxcUEFUSFxcUEFUSFxcdGhpbmcxLnhsc3gnLCAnQzpcXFBBVEhcXFBBVEhcXFBBVEhcXFBBVEhcXHRoaW5nMi54bHN4J10KCnBhdHRlcm4gPSByZS5jb21waWxlKHInXFwoW15cXF0rKVwueGxzeCcpCmZvciB4IGluIGZpbGVzOgoJbWF0Y2hlcyA9IHBhdHRlcm4uZmluZGFsbCh4KQoJcHJpbnQobWF0Y2hlcyk=