Structure-activity relationship of 7-aryl-2-anilino-pyrrolopyrimidines as Mer and Axl tyrosine kinase inhibitors

Figures & data

Figure 1. Structures and IC₅₀ values of TAM kinase inhibitors.

Table 1. Activity for TAM kinases of methoxy phenyl pyrrolopyrimidines.

Compound	R1	IC50 (nM)		% Inhibition at 1 µM
		MERTK	AXL	TYRO3
2		39	1240	38
3		95	751	44
4		>3000	>3000	12
5		>1000	>1000	0
UNC569		3	420	ND^a

Data are mean values. ^aND: not determined.

Scheme 1. Reagents and conditions: (a) (OH)₂B-Ar, Cu(OAc)₂, pyridine, 4 Å MS, CH₂Cl₂, rt, 6–24 h; (b) 2-bromothiazole, CuI, K₃PO₄, 1,2-trans-cyclohexanediamine, THF, 110 °C, 24 h; (c) BINAP, Pd₂(dba)₃, Cs₂CO₃, dioxane, 100 °C, 8 h; (d) HCl, i-PrOH, MW 160 °C, 1 h; (e) 4-(trifluoromethoxy)aniline, TEA, i-PrOH; (f) ethynyltrimethylsilane, Pd(PPh₃)₂, CuI, TEA, toluene, 80 °C, 4 h; (g) TBAF, THF, 60 °C, 4 h.

Scheme 2. Reagents and conditions: (a) amines, Pd₂(dba)₃, BINAP, Toluene, Cs₂CO_3, 100 °C, 6 − 24 h; (b) H₂, Pd/C, MeOH, rt, 3 − 9 h; (c) 7, 8, or 12, HCl, i-PrOH, MW 160 °C, 1 h; (d) DIBAL, toluene, 0 °C, 3 h; (e) 1-methylpiperazine, NaBH(OAc)₃, AcOH, DCE, rt, 12 h.

Figure 2. Predicted docking orientation of 16 and 25 with the Mer kinase domain (PDB ID: 3TCP). Docking mode of (a) 16 and (b) 25 with Mer. 2 D-interaction diagram of the binding model of (c) 16 and (d) 25. Estimated binding energies were −7.52 kcal/mol and −8.26 kcal/mol for 16 and 25, respectively. Hydrogen bonds and a salt bridge between the ligand and the backbone are shown in dashed lines. The docking study was performed by AutoDock Vina.

Table 2. Activities of 3-methoxy aniline derivatives of compound 3.

Compound	R2	R3	IC50 (nM)		% Inhibition at 1 µM
			MER	AXL	TYRO3
16		H	15	104	27
17		H	10	199	37
18		H	46	175	30
25	H		2	17	86
26	H		4	18	92
27	H		2	16	40
28	H		7	32	72
29	H		31	31	49
30	H		36	212	39
31	H		>3000	>3000	4
32	H		40	288	0
UNC569			3	420	ND^a

^aND: not determined.

Table 3. Inhibitory activity of R⁴ derivatives.

Compound	R^4	IC50 (nM)		%Inhibition at 1 µM
		MER	AXL	TYRO3
33		9	57	23
34		17	48	35
35		64	247	16
36		484	2018	55
UNC569		3	420	ND^a

^aND: not determined.

Figure 3. Inhibitory effect of 27 on Mer phosphorylation in a Mer-overexpressed human gastric cancer cell line, MKN28. Cells were treated with the indicated compounds at 0.5 and 0.1 μM for 1.5 h. UNC2025 and β-actin were used as a positive control and a loading control, respectively. Western blot analysis for phosphorylated and total Mer from a representative experiment is shown. Bar graph represents the relative intensities of the total and phosphorylated Mer as determined by band densitometry using image analysis software.