How to make AoO while grappling a target?

[Rainshine]

Background: Human Brawler, level 12, +46 on grapple checks, with constrict via Anaconda's Belt, pre-errata version of Final Embrace for Grab, Grabbling Style feat.
One issue I have is, although I can punch someone in the face (or kick them, or whatever), and start a grapple that way, as per the grappled text, I can no longer make Attacks of Opportunity. I'm wondering if anyone knows of a feat/item/feature that allows me to anyways? The only thing I can come up with right now is the Grab text

The creature has the option to... simply use the part of its body it used in the grab to hold the opponent. If it chooses to do the latter, it takes a –20 penalty on its CMB check to make and maintain the grapple, but does not gain the grappled condition itself So for a -20, I could probably just avoid the grappled condition altogether, and then make them, but that -20 is steep. Any other ideas?

[Ssalarn]

Unarmed Fighters can do it with the Clever Wrestler class feature gained at 7th level. (http://paizo.com/pathfinderRPG/prd/ultimateCombat/classArchetypes/fighter.html#clever-wrestler)

Feral Gnasher barbarians can do it at 6th level with the Improved Lockjaw class feature. (http://paizo.com/pathfinderRPG/prd/advancedRaceGuide/featuredRaces/goblins.html#improved-lockjaw)

The Strangler Brawler archetype gets the ability at 9th level. (http://paizo.com/pathfinderRPG/prd/advancedClassGuide/classOptions/brawler.html#practiced-strangler)

Tetori monks can do it at 4th level. (http://paizo.com/pathfinderRPG/prd/ultimateCombat/classArchetypes/monk.html#graceful-grappler)

I'm not aware of any other abilities that allow you to make attacks of opportunity while grappled, apparently Paizo considers that to be 4th-9th level class feature territory. Seems like your best bet might be seeing if you can retrain into the Strangler archetype.