Dimethylformamide → 4-Chloro-9-methoxybenzo[4,5]thieno[3,2-d]pyrimidine

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Reaction Steps

DMF (0.125 mL, 1.7 mmol) is added dropwise to a solution of (COCl)2 (0.15 mL, 1.68 mmol) in 1,2-dichloroethane (4.5 mL) at r.t. After gas evolution ceases, 9-methoxy-4-oxo-3H-benzothieno[3,2-d]pyrimidine (73.2 mg, 0.32 mmol) is added. The resulting mixture is heated at reflux for 4 hr. After the reaction is cooled to r.t., the black tar is filtered off. The filtrate is stripped to dryness and then mixed with water. A yellow solid forms and is collected via filtration. The solid is washed with water and air dried to give 4-chloro-9-methoxybenzothieno[3,2-d]pyrimidine (53 mg, 66%). 1H NMR (DMSO) δ9.17 (1H, s), 7.82-7.78 (2H, m), 7.3-7.2 (1H, m) , 4.06 (3H, s).

Provenance & Evidence