Table 2. SAR of R2 and Biochemical Activity in PI3K Isoforms¹⁸.

			PI3K enzyme IC50 (μM)
no.	R1	R2	α	β	δ	γ
16	2-Me,3-CF3	H	4.0	0.003	0.063	1.6
17	2-Me,3-Cl	H	2.5	0.003	0.040	2.5
18	2-Me,3-CF3	Me	2.5	0.0006	0.020	0.79
19	2-Me,3-Cl	Me	2.0	0.0005	0.010	1.0
20	2-Me,3-CF3	Et	>4.0	0.0005	0.013	1.3
21	2-Me,3-CF3	c-Pr	1.3	0.0005	0.016	1.0
22	2-Me,3-CF3	Ph	>3.2	0.050	0.50	4.0
23	2-Me,3-CF3	Bn	2.5	0.003	0.063	2.0
24	2-Me,3-CF3	CH2OH	0.63	0.0002	0.003	0.25
25	2-Me,3-CF3	CH2NH2	>2.5	0.003	0.16	>7.9
26	2-Me,3-Cl	CH2OH	0.50	0.0001	0.002	0.25
27	2-Me,3-Cl	OH	50	0.008	0.50	>6.3
28	2-Me,3-Cl	OMe	1.6	0.0003	0.010	0.40
29	2-Me,3-Cl	SH	2.0	0.005	0.050	>3.2
30	2-Me,3-Cl	SMe	2.0	0.0003	0.010	2.5
31	2-Me,3-Cl	SCH2-CO2H	0.40	0.00005	0.002	0.16
32	2-Me,3-Cl	NH2	0.25	0.0002	0.003	0.50