Use
DateTime::createFromFormat()
:$datetime = DateTime::createFromFormat("D F d, Y H:i a", 'Wed January 9, 2013 01:43 pm');
echo $datetime->format("Y-m-d H:i:s");
Trabalho confirmado
DateTime::createFromFormat()
:$datetime = DateTime::createFromFormat("D F d, Y H:i a", 'Wed January 9, 2013 01:43 pm');
echo $datetime->format("Y-m-d H:i:s");