6-Chloro-1-methyl-1H-pyrazolo[3,4-d]pyrimidin-4(7H)-one synthesis

Yield:5334-35-0 72.5%

Reaction Conditions:

with sodium hydroxide in water at 70; for 0.5 h;Sealed tube;

Steps:

Intermediate A 6-Chloro-l -methyl- l,5-dihydro-pyrazolo[3,4-d]pyrimidin-4-one

Intermediate A 6-Chloro-l -methyl- l,5-dihydro-pyrazolo[3,4-d]pyrimidin-4-one A sealed reaction vessel was charged with 4,6-dichloro-l-methyl-lH-pyrazolo[3,4- d]pyrimidine (US 20100015141 Al, 2.2 g, 10.8 mmol) and a 2M aqueous sodium hydroxide solution (50 mL). The vessel was sealed, and the reaction was heated to 70°C behind a blast shield and stirred for 30 min. The resulting clear solution was transferred with water, brought to pH 6-7 with a 2M aqueous hydrochloric solution and concentrated in vacuo. The remaining solids were filtered and rinsed with ethanol (-300 mL), and the filtrate was concentrated in vacuo onto Celite. Flash chromatography (40 g silica gel column, 1-10% methanol: methylene chloride) afforded 6-chloro-l-methyl-l,5-dihydro-pyrazolo[3,4-d]pyrimidin-4-one as a white solid (1.45 g, 72.5%). 1H NMR (300 MHz, DMSO-d₆) δ ppm 3.87 (s, 3 H) 8.06 (s, 1 H) 13.18 (br. s., 1 H). LC-MS calcd. for C₆H₆C1N₄0 [(M+H)⁺] 185, obsd. 184.9.

References:

WO2013/182546,2013,A1 Location in patent:Page/Page column 85