Table 3.

Inhibitory Activity of Compounds with P2 and P4 Modifications^a

Comp’d	P2	P4	PDE4D*	PDE4B*	Selectivity
	R2 =	R4 =	IC50 (nM)	IC50 (nM)	B/D
24	F		5530	>10000	>2
25	Cl		1150	9170	8
26	CF3		>10000	>10000	-
27 b	NO2		2.8	1120	400
28 b	Cl		5.1	720	141
29	OCHF2		11	1439	137
30	OCHF2		1.06	593	559
31	OCHF2		785	>10000	>13
32	OCHF2		15	>10000	>649
33	OCHF2		16	1260	81
34	OCHF2		21	>10000	>472
35	OMe		281	1060	4
36	OMe		3.9	621	159
37	OMe		12.3	764	62
38	OMe		10.2	1187	116
39	OMe		530	2270	4
40	OMe		372	>10000	>27
41 b	Cl		0.5	858	1672
42	OMe		3.5	853	244
43	OMe		2.1	513	242
44	OMe		743	>10000	>13
45	OMe		42	>10000	>238
46	OMe		23	646	28
47	OMe		17	>10000	>575

^aSee Table 1 for assay definitions.

^bThe assay results of the compounds were adopted from ref 22.