反应详情

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).

1. additionUpon complete addition
2. filtrationThe resulting yellow precipitate was filtered off
3. washwashed with water (250 mL)
4. temperatureto cool to r.t
5. filtrationThe resulting solid was filtered off
6. customair dried