Table 3. Measured inhibition constants of binding (K_i) for the (-)-stepholidine C3 analogues against the dopamine D3 receptor.

Compounds	C3-substituent	Kia,b
1a	Et	40.0
1b	n-Pr	46.0
1c	n-Bu	51.0
1d	n-Pen	33.0
1e	n-Hex	26.0
1f	2-fluroethyl	86.0

^a In nM. Experiments were carried out in triplicate—uncertainties are estimated as 13% of reported K_i;

^b[³H] N-methylspiperone used as radioligand; chlorpromazine used as a reference compound with K_i = 11.0 nM. The biochemical details of the assay are provided in the main text.