Table 2. STLC Analogues with Modified Trityl Rings^a.

compd	X	R1	R2	inhibition of basal ATPase activity, Kiapp (nM)	ligand efficiency	K562 cells, GI50 (nM)
11	S	2-Cl	(R)-CO2H	1783.9 ± 384.0	0.29	nd
12	S	3-F	H	377.4 ± 38.4	0.36	nd
13	S	3-Cl	(R)-CO2H	89.9 ± 18.5	0.36	2404 ± 222
14	S	3-Cl	H	297.8 ± 60.0	0.37	1045 ± 42
15	S	3-Br	H	293.9 ± 61.8	0.37	nd
16	S	3-Me	H	80.0 ± 23.9	0.40	698 ± 115
17	S	3-Et	H	5.9 ± 2.3	0.45	680 ± 84
18	S	3-i-Pr	H	10.3 ± 3.4	0.42	581 ± 68
19	S	3-n-Pr	H	29.6 ± 11.0	0.39	1760 ± 124
20	S	3-CF3	H	352.7 ± 27.9	0.33	nd
21	S	3-OMe	H	149.8 ± 18.5	0.37	nd
22	S	3-SMe	H	520.4 ± 87.6	0.34	1474 ± 330
23	S	3-OCF3	H	27.8 ± 5.0	0.37	1518 ± 164
24	S	3-COMe	(R)-CO2H	519.8 ± 102.0	0.30	964 ± 82
25	S	3-COMe	H	185.8 ± 30.4	0.35	706 ± 47
26	S	4-COMe	(R)-CO2H	271.7 ± 36.6	0.31	4266 ± 274
27	S	4-COMe	H	51.0 ± 21.6	0.38	705 ± 77
28	C	3-Cl	H	120.6 ± 20.7	0.35	596 ± 68
rac-29	C	3-Me	CO2H	12.2 ± 3.8	0.40	73 ± 3
(S)-29	C	3-Me	(S)-CO2H	11.1 ± 3.9	0.40	128 ± 15
(R)-29	C	3-Me	(R)-CO2H	6.4 ± 3.9	0.41	91 ± 9
30	C	3-Me	H	8.8 ± 1.8	0.46	200 ± 16
31	C	4-Cl	H	16.2 ± 3.1	0.44	337 ± 28
rac-32	C	4-Me	CO2H	7.5 ± 1.7	0.41	96 ± 5
(S)-32	C	4-Me	(S)-CO2H	16.7 ± 3.0	0.39	149 ± 6
(R)-32	C	4-Me	(R)-CO2H	5.4 ± 1.7	0.42	82 ± 4
33	C	4-Me	H	16.4 ± 1.9	0.44	219 ± 21

^and = not determined.