Table 2.

Piperidine hit series 2 SAR determined in the human sperm calcium influx assay.^[a]

Compd	R1	R2	IC50 [μM]
2 a		Cl	7.5±1.3
2 b		H	92±14
2 c		Cl	18±2
2 d			18±7
2 e		Cl	>100
2 f		Cl	>100
2 g		Cl	>100
2 h		Cl	>100*
2 i		Cl	>100*
2 j		Cl	87*
2 k			>100*
2 l			>100*

[a] CatSper activated by 3 μM progesterone. IC₅₀ values are means±SEM of three independent experiments. *IC₅₀ values are means of two independent experiments.