alias with std::vector does't work

I am trying to create an alias for a simple std::vector but g++ 5.1 doesn't like it. I understood that an alias is a substitute (more intelligent and strongly typed) for the old typedef. Am I missing something? Below my code

 using List = std::vector<int>;
 using Ptr  = List::iterator;

The error I have is

 error: expected name specifier before 'List'

I am compiling with -std=c++0x flag.