If you need to escape characters in a regular expression, you can reliably use either the quotemeta function or the delimiters \Q and \E, as described in Quote and Quote like Operators. For example, you would successfully split with my @arr = split /\Q),(\E/, $str;.

On examining your input, it's possible you'll get more mileage from either a state machine character-wise parser, a regular expression, or my favorite in this context, multiple operations including a different basic split. Since you appear to be separating tuples, you could use my @arr = split /(?<=\))\s*,\s*(?=\()/, $str; to separate the tuples, and then deal with each one individually.