Typically it actually looks like the opposite. When I look at, eg, North Korea or Iran - if I were going to try and make them wealthy it is mostly internal policies that are the problem and not external ones.
If North Korea set itself up with single digit % company and income tax combined with a strong rule of law, local education programs and a liberal economy it would barely matter what sanctions were imposed on them. A tide of money would flow in and they'd eventually be wealthy under their own power anyway if not. Although it isn't obvious why anyone would sanction a small well run country; there is a correlation between sanctions and incompetent governance.