There was no shortage of chances with the woodwork being struck no fewer than three times but it was the Xeneize who set up a date in the final against Brazilian side Corinthians
The Argentines held a 2-0 lead from the first leg but never really looked like seeing that deficit overturned in the return fixture. La U lacked their typical fluidity and intensity in the opposing half but both teams struggled to make the most of their chances in an entertaining draw.
Jorge Sampoli set his side out in a more attacking 4-3-3 formation with the wing-backs pushing forward to contribute to the attack. However, this left his two centre-back extremely exposed throughout and it was Boca who created the first opportunity.
In the eighth minute Pablo Mouche latched onto a ball over the top and drove to the byeline. He delivered an aerial cutback from the left that was met by Juan Roman Riquelme but his first-time volley rattled the bar.
It served to shock the hosts into action and they began to apply more pressure in the Boca half, but they continued to leave too many spaces at the back that Boca were exploiting. The Argentines could have opened the scoring again when Mouche showed great pace to spring the offside trap yet he could only muster a tame effort that Johnny Herrera gathered easily.
Although Junior Fernandes beat Rolando Schiavi to Marcelo Diaz's free kick in the 24th minute, Agustin Orion reacted briskly to dive to his left and turn the header behind for a corner.
The Azul continued to be negligent defensively and it became more worrying as Riquelme began to find his passing range. He picked out Mouche twice with scything through-balls but the 24-year-old was not proving clinical in front of goal and he failed to make the most of both chances.
La U emerged for the second half looking far more at ease on the ball and there were less errant passes. During the break Sebastian Ubilla replaced Francisco Castro and one of his first actions was to win a free kick in the 53rd minute which Diaz saw come back off the frame of the goal.
Mouche's profligacy in the area continued with another limp effort on goal moments later and it seemed to be contagious as after another counterattack Riquelme sent a low shot straight into the arms of Herrera.
Diaz continued to be the main threat for the hosts and on the hour mark he unleashed a ferocious 20-yard strike that arrowed towards Orion's goal. It was struck sweetly but the keeper had eyes on it all the way and turned it over the bar.
With 72 minutes on the clock Eugenio Mena sent a ball into the box from wide on the left. Angelo Henriquez found space between the centre-backs to get his head on it and aimed for the far corner but his connection was not the best and Orion was equal to it.
It was affirmed that it would not be La U's night in the closing stages when Raul Ruidiaz struck the bar once more and the no fewer than three players failed to make contact with a flick on from Diaz's corner in the 88th minute.
Boca remained resolute until the whislte to set up a date in the final with Corinthians who defeated defending champions Santos in the tournament's other semi-final.