Ammonium Hydroxide → (3R)-3-cyclopropyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)pyrazol-1-yl]propionitrile

Participants

Reaction Steps

A solution of (3R)-3-cyclopropyl-3-{4-[7-(2-trimethylsilanyl-ethoxymethyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl]-pyrazol-1-yl}-propionitrile ((R)-29, 102 g, 0.25 mol, 1.0 equiv) in MeCN (900 mL) and H2O (75 mL) was treated with solid lithium tetrafluoroborate (LiBF4, 186.0 g, 2.0 mol, 8.0 equiv) in portions (the reaction temperature increased from 15 to 38° on addition). The resulting reaction mixture was then heated at gentle reflux (light suspension formed) for 20 h. When LCMS showed the cleavage of the SEM group was complete, the reaction mixture was cooled to room temperature and subsequently to 12° before being adjusted to pH 9-10 with addition of an aqueous NH4OH solution (20%, 80 mL). The resulting suspension was stirred at room temperature until LCMS showed no N-hydroxymethyl intermediate (M++H=309) remained, typically within 24-36 h. During this period the pH of the reaction mixture dropped to 7-8, additional aqueous NH4OH solution (20%) was added to readjust the mixture to pH 9-10. The mixture was diluted with acetonitrile (300 mL), filtered, washing solids with acetonitrile (500 mL). The turbid filtrate was concentrated under reduced pressure to remove most of the MeCN to give a thick oil that contained some solids. The mixture was slowly diluted with H2O (500 mL) and the turbid solution was seeded. The solution was then concentrated under reduced pressure at room temperature until a thick suspension had formed. The suspension was further diluted with H2O (1 L) and the resulting suspension was stirred at room temperature for 2 h. The solids were collected by filtration, washed with H2O (2×500 mL) and suction dried on funnel for 1.5 h. 19F NMR showed a small amount of inorganic fluoride present and TLC (5% MeOH/EtOAc) showed a small amount of baseline material existed. Therefore, the crude solids were re-slurried in H2O (1 L) with mechanical stirring for 1 h before being collected by filtration and washed with H2O (500 mL). The wet cake was suction dried on the funnel for 1.5 h then dried in a vacuum oven at 45-50° C. for 16 h to give (3R)-3-cyclopropyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)pyrazol-1-yl]propionitrile ((R)-30, 60.8 g, 69.6 g theoretical, 87.4% yield) as a off-white solid. For (R)-30: C15H14N6 (MW, 278.31), LCMS (EI) m/e 279 (M++H).

Provenance & Evidence