Synthesis
General procedure for the synthesis of 4-chloro-6-hydrazinopyrimidines from 4,6-dichloropyrimidines: 4,6-dichloropyrimidines (15 g, 100 mmol) were dissolved in ethanol in a 250 mL three-necked flask and cooled to 0-5 °C. Hydrazine hydrate (4.7 mL, 120 mmol) was slowly added dropwise to the reaction flask under cooling conditions. After the dropwise addition, the reaction mixture was stirred at room temperature for 90 minutes. The reaction progress was monitored by thin layer chromatography (TLC). After completion of the reaction, the mixture was poured into water and the crude product was precipitated. Purification by ethanol recrystallization gave 4-chloro-6-hydrazinopyrimidine (A) as a light yellow solid. The yield was 95%; the product was a pale yellowish-white solid; the Rf value was 0.5 (unfolding agent: hexane/ethyl acetate, 4:1); the melting point was 164 °C. 1H NMR (DMSO-d6, 400 MHz) δ= 8.83 (s, 1H), 8.17 (s, 1H), 6.76 (s, 1H), 4.50 (s, 2H); EI-MS (m/z): 145.02 (M + 1).
References
[1] Journal of Molecular Structure, 2019, vol. 1175, p. 551 - 565
[2] Chemical Biology and Drug Design, 2018, vol. 92, # 3, p. 1683 - 1691
[3] Patent: WO2008/42639, 2008, A1. Location in patent: Page/Page column 81
[4] Synlett, 2010, # 14, p. 2179 - 2183
