(Diethylamino)sulfur trifluoride → tert-butyl 4-((5R,7S)-7-fluoro-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)piperazine-1-carboxylate

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Reaction Conditions

Reaction Steps

tert-Butyl 4-((5R,7R)-7-hydroxy-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)piperazine-1-carboxylate (1.190 g, 3.558 mmol) was dissolved in methylene chloride (55 mL) and cooled to −20° C. The solution was treated with DAST (1.410 mL, 10.68 mmol) and stirred at −20° C. for 1 hour. The reaction was quenched with ice and then warmed to ambient temperature. The mixture was diluted with saturated NH4Cl and separated. The aqueous phase was extracted with methylene chloride (2×), and the combined organics were dried over Na2SO4 and concentrated to a dark oil. This oil was chromatographed on SiO2 (Biotage 40S, load with methylene chloride) then eluted with 2.5% MeOH/DCM then 3.5% MeOH/DCM. The mixed fractions were concentrated, and the material was re-chromatographed on SiO2 (Biotage 40S, load with DCM) and eluted with 2 hexane/EtOAc. The product was collected as a dark oil to give tert-butyl 4-((5R,7S)-7-fluoro-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)piperazine-1-carboxylate (0.725 g, 61%). LCMS (APCI+) m/z 337.0 [M+H]+; Rf 3.13 min.

Provenance & Evidence