Table 2. SAR Study of Compounds 21–33.

No.	R4	EC50(nM)a
21	2-Cl	1143 ± 235
22	3-Cl	257 ± 37
23	4-Cl	66 ± 4.2
24	3-OH	1821 ± 371
25	3-OMe	57 ± 1.7
26	3-OEt	110 ± 25
27	3-OPr	69 ± 9.7
28	4-OMe	94 ± 9.6
29	3-ethynyl	4477 ± 1040
30	4-ethynyl	817 ± 189
31	3-cyano	4060 ± 477
32	4-cyano	3489 ± 184
33b	3,4-dimethoxy	25 ± 0.57

^aEC₅₀: cellular apoptosis inhibition in the U2OS_Bim cell line.

^bCompound A.