THe Louisianna Purchase was probably unconstitutional. Nobody objected at the time.
It probably was and there was objection after the fact; primarily I think because it was done on the sly and involving a large sum of money during a time that we didn’t have all that much in our treasury. It didn’t take too long for most to realize that it was the right thing to do and that the financial rewards to the nation and commerce far outweighed the points of dissent.
It was clearly unconstitutional and Jefferson admitted it, but he did it anyway.