Phosphorus oxychloride → tert-Butyl 4-chloro-5,6-dihydropyrido(4',3':4,5)thieno(2,3-d)pyrimidine-7(8H)-carboxylate

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Reaction Conditions

Reaction Steps

To a solution of phosphorous oxychloride (30 mL) was added triethylamine (30 mL) over 15 mins at 0° C. under argon. 4-oxo-3,5,6,8-tetrahydro-4H-9-thia-1,3,7-triaza-fluorene-7-carboxylic acid tert-butyl ester (4.20 g, 14 mmol) was then added to the flask. The reaction mixture was stirred at 0° C. for 30 mins then heated at 65° C. for 2 h. The reaction mixture was cooled to rt before concentrated in vacuo. The residue was coevaporated with toluene (2×200 mL). DCM (50 mL) was added to the solid residue and the reaction mixture was quenched with ice/saturated aqueous NaHCO3. The resulting mixture was extracted with DCM (3×100 mL). The combined organic layers was dried over sodium sulfate, filtered and concentrated in vacuo to yield 4.08 g (12.5 mmol, 89%) of a light yellow solid. 1H-NMR (CD2Cl2-d2) δ 8.74 (s, 1H), 4.74 (s, 2H), 3.78 (t, 2H), 3.19 (t, 2H), 1.49 (s, 9H); LCMS RT=3.53 min, [M+H]+=326.0.

Provenance & Evidence