Non-steroidal pregnancy-terminating agents:: Design, synthesis and structure-activity relationships of 2-aryl-1,2,4-triazolo[1,5-a]pyridine

The syntheses and the pregnancy-terminating activity relationships of compounds 5a-n are reported. Compounds 5b and 5l are found to be more potent than DL-111-a known drug having effective pregnancy-terminating activity in vitro. Further research shows compounds 5b and 5l have the same activity as DL-111 in vivo. We also found an exciting result that they have excellent anti-implantation activity after oral administration. (C) 2002 Elsevier Science Ltd. All rights reserved.