you can, however I hear doing some of the reputation quests before a certain part of the Thieves Guild storyline can bug out, preventing you from being able to become Guildmaster... sadly, I can't remember what point...
although, I personally have never experienced it..
still, even if you do the Radiants, just to be safe I would suggest not actually obtaining the Reputation Quests till after the TG MQ..
I have always finished the special jobs before finishing the thieves guild quest-line...never had a problem(PS3)
I have never personally had an issue either, but i have heard of people where Brynjolf won't trigger the dialogue to become guildmaster...