Is it permissible in Islam to not listen to the parents when what they are asking us to do is against the sharia?
Yes sure you can just not listen to your parents regarding marriage but sure you have not to hurt their feelings with your refuse, so you have to be polite in your refuse giving reasonable reasons for why you don't want to be married.
Another thing you have to keep in your mind the Prophet Mohammad say:
النكاح سنتي ومن رغب عن سنتي فليس مني
Marriage is my Sunnah and who refuse my sunnah then he is not on my way.
So you can refuse if you have reasonable logical reasons without being refusing marriage at all
Allah says in the Quran that the relations that have the most right on a person after Allah and his messenger is his parents. Disobeying parents is considered a major sin.
Some more references can be found here
One place where the condition of disobeying the parents is mentioned is the following verses.
31:14-15 And We have enjoined upon man [care] for his parents. His mother carried him, [increasing her] in weakness upon weakness, and his weaning is in two years. Be grateful to Me and to your parents; to Me is the [final] destination.
But if they endeavor to make you associate with Me that of which you have no knowledge, do not obey them but accompany them in [this] world with appropriate kindness and follow the way of those who turn back to Me [in repentance]. Then to Me will be your return, and I will inform you about what you used to do.
The ONLY reason to disobey parents is they ask you to commit "shirk" (associating partners with Allah) as this is something that, if you confront Allah, with this sin, then there is no pardon.
If you want to disobey parents against in any other matter, then make sure that is a direct order of God and not your (or someone else's) interpretation of what God ordered. I don't want to stand in front of God on the day of resurrection and He telling me, ... that is not something I ordered, but I ordered you to obey your parents and you did not do that...
I would advise you to take a cautionary approach and unless it is not somethings so blatant as asking you to commit shirk, obey your parents.