Synthesis
The general procedure for the synthesis of 5-amino-2-methylpyrimidine from 2-methyl-4,6-dichloro-5-aminopyrimidine is as follows:
Example 77: Preparation of (1S,2R)-2-(4-(diisobutylamino)-3-(3-(2-methylpyrimidin-5-yl)ureido)phenyl)cyclopropanecarboxylic acid 77A.
Step 77A: Synthesis of 5-amino-2-methylpyrimidine
1. 4,6-dichloro-2-methylpyrimidin-5-amine (2 g, 11.23 mmol) was dissolved in ether (93 ml).
2. aqueous solution of sodium hydroxide (7.37 g, 184 mmol) (22.05 ml) and 10% palladium-carbon catalyst (0.161 g, 1.517 mmol) were added to the above solution.
3. The reaction mixture was subjected to a hydrogen atmosphere at 50 psi and the reaction was shaken on a Par oscillator for 22 hours at room temperature.
4. After completion of the reaction, the reaction mixture was filtered through diatomaceous earth and the filter cake was washed with dichloromethane (DCM).
5. The solvent in the filtrate was evaporated to give a yellow residue.
6. The residue was resuspended in a solvent mixture of DCM and water.
7. The pH of the aqueous layer was adjusted to about 6 with 4N HCl, followed by extraction of the aqueous layer with DCM (3 times).
8. The organic phases were combined, dried with anhydrous Na2SO4, filtered and concentrated to give a yellow residue.
9. As the aqueous phase still contained product, the aqueous phase was evaporated to give a yellow solid.
10. The solid was dissolved in a solvent mixture of methanol (MeOH) and DCM and filtered to remove the insoluble salt.
11. The filtrate was evaporated to give a yellow residue.
12. The products from the extracted and aqueous layers were purified separately by fast chromatography and the purified products were combined to give 77A (off-white solid, 0.968 g, 8.87 mmol, yield 79%).
Product characterization: 1H NMR (400 MHz, chloroform-d) δ 8.14 (s, 2H), 3.60 (br.s., 2H), 2.61 (s, 3H).
References
[1] Patent: WO2014/150677, 2014, A1. Location in patent: Page/Page column 121; 122
[2] Helvetica Chimica Acta, 1958, vol. 41, p. 1806,1812
