Lorentz force and potential energy

(1) the Lorentz force is F = q[E + (v X B)]

Where E = -del phi - dA/dt

And B = del X A

(2) The potential energy equals U = qphi – qA dot v

How do I get from 1 to 2?

I’ve tried going from 1 to 2 and from 2 to 1 and I can’t figure it out. This isn’t a homework problem it comes form page 22 of Goldstein’s Mechanics.

Thanks