Acetic Acid → Benzo[b]thiophene-2,5-dicarboxylic acid 2-tert-butyl ester 5-methyl ester

Participants

Reaction Conditions

Reaction Steps

To a suspension of sodium sulfide (7.95 g, 102 mmol) in anhydrous DMF (200 mL) at 0° C. were added acetic acid (5.80 mL, 102 mmol) and additional DMF (100 mL). The mixture was allowed to stir at 0° C. for 30 min and chloroacetic acid tert-butyl ester (14.6 mL, 102 mmol) was added followed by additional DMF (50 mL). The resulting mixture was allowed to stir at 0° C. for 30 min and at rt for 30 min. To this mixture were added K2CO3 (16.4 g, 119 mmol) and 3-formyl-4-nitro-benzoic acid methyl ester (17.68 g, 84.55 mmol) in DMF (30 mL). The resulting mixture was heated at 55° C. for 22 h, cooled to rt and poured into water (1.2 L). The solid formed was filtered, washed with water (300 mL) and crystallized from MeOH to give benzo[b]thiophene-2,5-dicarboxylic acid 2-tert-butyl ester 5-methyl ester as a pale solid. MS (EI): cal'd 237.0 (M-tbutyl+H+), exp 237.1 (M-tbutyl+H+).

Provenance & Evidence