Hydrochloric Acid → Methyl 5-nitro-1-benzothiophene-2-carboxylate

Beteiligte Stoffe

Reaktionsschritte

Methyl thioglycolate (19.62 mL, 0.216 mol) was added dropwise, via syringe pump, to a stirred suspension of 95% sodium hydride (5.99 g, 0.237 mol) in dry N,N-dimethyl-formamide (400 mL) at r.t. under nitrogen (CAUTION: hydrogen evolution). Upon complete addition, the reaction was stirred for 10 min and then a solution of 2-chloro-5-nitrobenzaldehyde (40.0 g, 0.216 mol) in DMF (120 mL) was added. The solution turned orange and a gentle exotherm was observed. After 1h, the now yellow mixture was heated to 100° C. for 5 h. The mixture turned amber in appearance. After cooling to r.t. the mixture was poured into 1 N aqueous hydrochloric acid (500 mL). The resulting yellow precipitate was filtered off and washed with water (250 mL). The solid was suspended in hot methanol/ethyl acetate (1:1) (1000 mL) and allowed to cool to r.t. The resulting solid was filtered off and air dried to yield methyl 5-nitrobenzo[b]thiophene-2-carboxylate (33.77 g, 66%) as a tan amorphous solid. 1H NMR δ (d6-DMSO, 400 MHz) 3.92 (s, 3H), 8.32 (dd, J=9, 2 Hz, 1H), 8.37 (d, J=9 Hz, 1H), 8.45 (s, 1H), 9.00 (d, J=2 Hz, 1H).

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