A series of 3,5-diaryl-s-triazoles were synthesized and evaluated as postimplantation contragestational agents. The introduction of various substituents (e.g., an o-alkyl chain on one phenyl and a m-alkoxy group on the other) was found to increase the potency. Several compounds with very high pregnancy-terminating activity in both hamsters and rats were obtained. One of these, 3-(2-ethylphenyl)-5-(3-methoxyphenyl)-s-triazole, DL 111 (36), was selected for detailed evaluation in various animal species. A synthetic scheme for the preparation of these compounds and preliminary structure-activity relationships are presented.

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Four non‐hormonal, pregnancy‐terminating compounds have been studied in bitches. One of these, 2‐(4‐chlorophenyl)‐s‐triazole[5,1‐a]isoquinoline (DL 717‐IT or L 12717), has been found to be very efficacious after a single subcutaneous injection. This compound appears to be promising for use in veterinary practice.