He was singing in the famous Franco Zeffirelli production of La BohÃ me , with Mirella Freni singing Mimi and Herbert von Karajan conducting . . Shortly after , on 28 April , Pavarotti made his La Scala debut in the revival of the famous Franco Zeffirelli production of La BohÃ me , with his childhood friend Mirella Freni singing Mimi and Herbert von Karajan conducting .