No, it is not possible to move candidates into the Talent Pool from an active job. The Talent Pool has been designed as a solution for candidates who are interested in your company but don’t fit into a current posted job.
A workaround would be tagging the candidates that you find interesting but who are not a good fit for your current positions with a corresponding tag, for example, #future_sales. Then when a similar position is open you will be able to filter your Candidate Database based on these tags (searches include archived jobs) and move matching candidates from there to the new job.