Why is protected constructor raising an error this this code?

One question about protected constructor. I learnt that the protected constructor can be used in the derived class. How ever, I found the code below has an error. Why does it happen like this?

class A
{
    protected:
        A(){}
};

class B: public A {
    public:
        B() {
            A* f=new A();           // Why it is not working here
        }
};