Isothiocyanato-2-pyridinylbenzoxazoles. The low activity level of the 4-pyridinyl derivative 1 in sheep (40%) had been anticipated based on our earlier experience with benzimidazoles. 2 However, the poor activity of the 2-pyridinyl isomer 2 in sheep (35%) was unexpected. Surprising, then, was the activity in sheep of the 3-pyridinyl isomers 3, 4, and 5 with 69, 78, and 99% reduction in the fecal egg count, respectively. The activity of 5 was still observed ...