Groenig created The Simpsons
B Real was a guest on Simpsons (homerpalooza episode)
B Real to Outkast
Ouykast to Erykah
Erykah to The Roots

OR

Groenig to Simpsons
Michael Jackson guested on The Simpsons/Wrote "Do The Bartman"
Michael is currently working with Swiss Beats
Swiss to Eve
Eve to The Roots

OR

Groenig to Futurama
Beastie Boys had guest voices on Futurama
Beasties to Q-tip
Tip to The Roots

I could go on, but I don't think I could it get it down to less than four.