Benzenepropanoic acid → Benzo(b)thiophene-2-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

Thionyl chloride (5 eq.) was added dropwise to a round-bottom flask containing a mixture of hydrocinnamic acid (1 eq.) and pyridine (0.1 eq.) heated to 150° C. TLC after 3 h showed complete consumption of starting material. The reaction mixture was cooled to it and water (10 vol), 35% HCl (1 vol.), and THF (15 vol) were added and the mixture heated at 60° C. for 30 minutes. After 30 minutes, the THF was removed in vacuo and the obtained precipitate was filtered, dissolved in a 3:1 water:ethanol mixture (20 vol) and heated at 90° C. for 1 hr. After 1 h, the solution was cooled to it and allowed to stir overnight. The separated solid was filtered and recrystallized from toluene to get the corresponding benzothiophene-2-carboxylic acid. The results for various substituted chlorobenzothiophene carboxylic acids are given in Table 1.

Provenance & Evidence