3,4-dihydro-2H-pyran → 6-chloro-4-(8-oxa-3-aza-bicyclo[3.2.1]oct-3-yl)-1-(tetrahydro-pyran-2-yl)-1H-pyrazolo[3,4-d]pyrimidine

Participants

Reaction Conditions

Reaction Steps

6-Chloro-4-(8-oxa-3-aza-bicyclo[3.2.1]oct-3-yl)-1H-pyrazolo[3,4-d]pyrimidine (21 mmol) is taken up as a suspension in dry ethyl acetate (50 mL). Following the addition of 4-toluenesulfonic acid monohydrate (25 mg), the mixture is heated to 60° C. and 3,4-dihydro-2H-pyran (2.5 mL) is added in drops. The reaction mixture is maintained at 60° C. for 18 hours and is then concentrated under reduced pressure. The residue is purified by flash silica gel chromatography. Following concentration of fractions, 6-chloro-4-(8-oxa-3-aza-bicyclo[3.2.1]oct-3-yl)-1-(tetrahydro-pyran-2-yl)-1H-pyrazolo[3,4-d]pyrimidine is obtained. 6-Chloro-4-(8-oxa-3-aza-bicyclo[3.2.1]oct-3-yl)-1-(tetrahydro-pyran-2-yl)-1H-pyrazolo[3,4-d]pyrimidine (3.1 mmol) is coupled to 4-acetamidophenylboronic acid (0.83 g, 4.6 mmol) with tetrakis(triphenylphosphine) palladium (0) (2.5 mol %), 2 M aqueous sodium carbonate solution, and ethylene glycol dimethyl ether (DME) and under microwave irradiation (175 C, 10 min). Following an aqueous workup and flash chromatography, N-{4-[4-(8-Oxa-3-aza-bicyclo[3.2.1]oct-3-yl)-1-(tetrahydro-pyran-2-yl)-1H-pyrazolo[3,4-d]pyrimidin-6-yl]-phenyl}-acetamide is obtained. N-{4-[4-(8-Oxa-3-aza-bicyclo[3.2.1]oct-3-yl)-1-(tetrahydro-pyran-2-yl)-1H-pyrazolo[3,4-d]pyrimidin-6-yl]-phenyl}-acetamide (1.2 mmol) is taken up in dioxane (5 mL), treated with 4 M hydrogen chloride in dioxane (5 mL), and allowed to stir at room temperature for 3 days. The slurry is concentrated and purified by reverse phase preparative high performance liquid chromatography, employing a Phenomenex Prodigy 250 mm×21.2 mm 5 μm column and a 5% acetonitrile/95% water/0.1% trifluoroacetic acid to 100% acetonitrile gradient over 40 minutes. After concentration, N-{4-[4-(8-Oxa-3-aza-bicyclo[3.2.1]oct-3-yl)-1H-pyrazolo[3,4-d]pyrimidin-6-yl]-phenyl}-acetamide is provided.

Provenance & Evidence