It depends on why the drug distribution-related conviction was overturned. If it was overturned due to some procedural error, that does NOT mean that no drug distribution occured--it only means that there was some flaw in the case. Therefore, since there still could have been illegal activities, there could have been money laundering of the proceeds. If the case were overturned because a higher court (or trial court on remand) found that there was no illegal distribution, then that might well lead to overturning the money laundering case, since if any money was not illegally obtained, there would be no laundering.