$re = '~<\s*meta\b.*\bproperty="(og:[^"]+)"\s.*\bcontent="([^"]*)~';
$str = '<meta property="og:title" content="111">
<meta data-one="true" property="og:description" content="222">
<meta data-two="true" property="og:image" content="333">
<meta data-three="true" data-another="true" property="og:url" content="444">
<meta data-four="true" data-another="true" notaproperty="og:url" content="444">
';
preg_match_all($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