Does he enter a square adjacent to you? Yes.
Does charging have a special quality that negates opportunity attacks? No.
Polearm Gamble -usually- allows you to make that Opportunity Attack against the charging foe.
A Raging Barbarian charging with Howling Strike will not, however, because Howling Strike negates OAs while charging. As well, there's a feat that allows Eladrin to teleport as part of their charge, which also negates Opportunity Attacks (all Opportunity Actions, in fact.)