$re = '/ad</div>((?!<div>).)*<div>(((?!<\/div>).)*)</div>/s';
$str = '""" <div>ad</div> \\n\\n <div> correct
value </div> <div> wrong value </div> """';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php