Synthesis
General procedure for the synthesis of methyl 5-amino-1-methyl-1H-pyrazole-4-carboxylate from the compound (CAS:13974-74-8) and methylhydrazine: 150 mL of isopropanol was added to 7.4 mL (141 mmol) of methylhydrazine and the resulting mixture was cooled to 15°C (internal temperature). To the cooled mixture was slowly added 7.0 g (49.6 mmol) of intermediate (a), followed by heating the reaction mixture to 50°C and stirring for 1 hour and 40 minutes. Upon completion of the reaction, the reaction solution was concentrated under reduced pressure and then the concentrate was purified by silica gel column chromatography to give 10.5 g (white powder; yield: 50%) of intermediate (b). The NMR data of the obtained intermediate (b) were as follows: 1H-NMR (300 MHz, CDCl3): δ 7.60 (s, 1H), 4.95 (brs, 2H), 3.80 (s, 3H), 3.60 (s, 3H).
References
[1] Patent: WO2009/110643, 2009, A1. Location in patent: Page/Page column 100
[2] Patent: WO2010/104210, 2010, A1. Location in patent: Page/Page column 36-38
[3] Patent: EP2230278, 2010, A2. Location in patent: Page/Page column 33
[4] Patent: EP2228409, 2010, A2. Location in patent: Page/Page column 30
[5] Patent: US2011/17099, 2011, A1. Location in patent: Page/Page column 12
