Table 3. STLC Analogues with Modified Trityl Rings^a.

compd	R1	R2	inhibition of basal ATPase activity, Kiapp (nM)	ligand efficiency	K562 cells, GI50 (nM)
34	2-OH	CO2H	1978.5 ± 587.3	0.29	nd
35	3-OH	CO2H	48.8 ± 22.0	0.37	2559 ± 302
36	3-OH	H	200.3 ± 51.9	0.38	555 ± 121
37	3-CN	H	450.6 ± 197.4	0.35	2128 ± 108
38	3-CH2NH2	H	838.2 ± 164.1	0.33	2018 ± 244
39	3-CH2NHCOMe	H	829.2 ± 100.5	0.30	2133 ± 135
40	3-CO2H	H	990.6 ± 156.9	0.31	2138 ± 241
41	3-CONH2	CO2H	329.9 ± 49.2	0.30	16749 ± 6112
42	3-CONH2	H	419.7 ± 38.8	0.33	802 ± 51
43	3-CONHMe	H	887.8 ± 74.9	0.31	982 ± 72
44	3-CONMe2	H	6055.6 ± 1123.0	0.25	2831 ± 171
45	3-SO2Me	H	2089.6 ± 246.6	0.29	2559 ± 180
46	4-CN	H	432.4 ± 91.2	0.35	2178 ± 149
47	4-CH2OH	H	311.2 ± 31.8	0.35	783 ± 50
48	4-CH2NH2	H	2942.4 ± 782.8	0.30	2594 ± 191
49	4-CH2NHCOMe	H	1721.3 ± 294.5	0.28	2904 ± 150
50	4-CONH2	H	3228.6 ± 447.4	0.29	4335 ± 341
51	4-CONHMe	H	2030.8 ± 671.6	0.29	3954 ± 293
52	4-CONMe2	H	1526.7 ± 359.7	0.28	2911 ± 271
53	4-SO2Me	H	1212.1 ± 179.9	0.30	2735 ± 482

^and = not determined.