Table 3.

Structure and biological activity of compounds 18-26, 33

Compd. No.	R1	R2	Ki (μM)
18	H	H	9.2
19	Cl	H	10
20	H	Cl	3.5
21		H	0.92
22	H		0.68
23		H	1.7
24	H		0.74
25	H		2.4
26	H		0.37
33	H		1.6