Table 1.

Relative Binding Affinity (RBA) of series I (2a–j), series II (4a–e), series III (6a–g) and series IV (8a–d) for ERα and ERβ^α.

Entry	compound	Core	R	ERb	ERb	β/α
1	2a		H	0.61 ± 0.03	2.87 ± 0.20	4.70
2	2b		2-Me	5.60 ± 0.43	11.1 ± 0.73	1.98
3	2c		3-Me	<0.01	0.94 ± 0.05	>94
4	2d		3,5-diMe	<0.01	1.21 ± 0.02	>121
5	2e		2,6-diMe	4.09 ± 0.05	4.12 ± 0.15	1.00
6	2f		2-F	5.90 ± 0.90	24.3 ± 0.52	4.11
7	2g		2-Cl	6.11 ± 0.05	12.7 ± 3.66	2.07
8	2h		3-Cl	0.29 ± 0.02	1.52 ± 0.19	5.10
9	2i		2-F	2.02 ± 0.19	1.83 ± 0.30	0.90
10	2j		4-F	0.92 ± 0.07	3.10 ± 0.73	3.37
11	4a		H	0.32 ± 0.04	2.01 ± 0.11	6.28
12	4b		2-Me	0.27 ± 0.06	6.70 ± 0.49	24.81
13	4c		3-Me	0.71 ± 0.09	0.62 ± 0.12	0.87
14	4d		3-F	0.58 ± 0.14	1.56 ± 0.23	2.67
15	4e		2-F	0.89 ±0.32	1.95 ± 0.58	2.19
16	6a		H	5.04 ± 0.40	11.7 ± 0.01	2.32
17	6b		2-Me	14.6 ± 2.84	10.8 ± 0.77	0.74
18	6c		3-Me	1.39 ± 0.71	6.12 ± 2.40	4.40
19	6d		3,5-diMe	2.17 ± 0.71	0.93 ± 0.07	0.43
20	6e		3-Cl	2.98 ± 0.24	0.74 ± 0.20	0.25
21	6f		4-F	1.31 ± 0.05	0.37 ± 0.03	0.28
22	6g		2-F	3.35 ± 0.83	4.36 ± 0.49	1.30
23	8a		H	6.38 ± 0.23	7.39 ± 1.30	1.15
24	8b		3-Me	1.25 ± 0.26	12.4 ± 1.47	9.92
25	8c		3,5-diMe	4.91 ± 0.34	2.73 ± 0.11	0.55
26	8d		3-Cl	1.62 ± 0.31	1.71 ± 0.24	1.06
27	4OHT			13.8 ± 0.2	12.6 ± 1.7	0.91

^aTo simplify comparisons between compounds in closely related series, we designate locant positions of the substituents on the phenyl groups with respect to the selenophene core; locant positions on the selenophene core itself are given by numbers in italics.

^bRelative Binding Affinity (RBA) values are determined by competitive fluorometric binding assays and are expressed as IC₅₀^estradiol/IC₅₀^compound × 100 ± the range (RBA, estradiol = 100%). In these assays, the K_d value of estradiol is 3.1 nM for ERα and 3.4 nM for ERβ, respectively. For details, see Experimental Section.