Uses
It is an important raw material and intermediate used in organic synthesis, pharmaceuticals, agrochemicals and dyestuffs and is also used in medicine.
Synthesis
General procedure: 4-(2-Thienyl)butyric acid (0.75 mmol, 1.0 eq.), trifluoroacetic anhydride (TFAA, 2.25 mmol, 3 eq.), and trifluoroacetic acid (TFA, 0.8 mL) were added to a 10 mL glass reaction vial equipped with a screw cap. The reaction mixture was stirred at room temperature for 12 h. The reaction process was monitored by thin layer chromatography (TLC) or gas chromatography-mass spectrometry (GC-MS). Upon completion of the reaction, the solvent was removed under reduced pressure and the resulting residue was purified by silica gel fast column chromatography (eluent: hexane/ethyl acetate mixed system) to finally obtain the target product 6,7-dihydro-4-keto-5-benzothiophene (6a).
References
[1] Tetrahedron Letters, 2018, vol. 59, # 10, p. 869 - 872
[2] Tetrahedron Letters, 2003, vol. 44, # 21, p. 4007 - 4010
[3] Heterocycles, 1996, vol. 43, # 1, p. 127 - 131
[4] Patent: WO2010/76188, 2010, A1. Location in patent: Page/Page column 17-19
[5] Patent: WO2005/77932, 2005, A2. Location in patent: Page/Page column 208
