If you are pitching to a big corporate, it is important to understand how their decision making process works. For example: going behind someone‘back and talk to her superior could back fire.
Big corporates can be big bureaucracies, but not all departments work like this. It could be that the junior team member you just skipped sits next to her boss who is forwarding the email she just received from you straight back at her. They do exist inside big corporates, proper functioning teams with an open work culture.
Some people who are very high up in the corporate hierarchy might actually not have that much decision power. It depends on the type of business. For example, someone can be global marketing manager of a big soft drinks brand, and have a lot of responsibilities. However, it could be that most tactical decisions are actually taken at the country level, in the local subsidiaries in wich the parent holds a minority stake.
In short, understand how your big corporate target works before planning your pitch strategy.