As explained in the journal Nature communications, the compound is called TDI-11861 and causes the disabling of the adenilil cyclase enzyme for a short time. In fact, this enzyme is essential for sperm to mature and be able to move through the female reproductive tract towards the egg.
In the mouse experiment, they have shown that the compound is safe and effective. When they were placed with females, it did not influence sexual activity and no female became pregnant. The females received sperm and stated that they were unable to germinate. However, when three hours passed, male mice became breeding again.
Men have a long way to go, but at least the first step has been a success.