Water → Allyl 2-amino-6-fluoro-pyrazolo[1,5-a]pyrimidine-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a suspension of allyl 3,5-diamino-1H-pyrazole-4-carboxylate 3 (42.72 g, 234.5 mmol) in DMSO (270.8 mL)/Water (270.8 mL), was added p-TsOH hydrate (46.72 g, 245.6 mmol) and 3-(diisopropylamino)-2-fluoro-prop-2-enal (described in Tetrahedron Letters, 33(3), 357-60; 1992) (38.69 g, 223.3 mmol). The reaction mixture was heated to 100° C. for 3 h during which time a solid slowly precipitated out of solution. The orange suspension was allowed to cool down to RT overnight. The solid was filtered, washed with water and dried under vacuum to give allyl 2-amino-6-fluoro-pyrazolo[1,5-a]pyrimidine-3-carboxylate 4a as a sand solid (45.05 g, 85% yield).

Provenance & Evidence