Indole (Sigma Aldrich), ≥99%, l3408
Acetyl chloride (Sigma Aldrich), reagent grade, 98%, 114189
Tin(IV) chloride (Sigma Aldrich), 99%, 208930
Toluene anhydrous, (Sigma Aldrich), 99.8%, 244511
Ethyl acetate (SD Fine Chemicals Ltd), directly used without drying

To the solution of indole (100 mg, 1 mmol) in anhydrous toluene (5 ml) at 0 °C was added acetyl chloride (121 µl, 2 mmol). After stirring for 15 minutes at 0 °C, a solution of tin(IV) chloride (197 µl, 2 mmol) in 3 ml anhydrous toluene was added. The resultant solution was further stirred for another 2 h at 0 °C,  followed by addition of 8 ml of 8% NaHCO₃ solution (dropwise). This reaction mixture was extracted with ethyl acetate (50 ml X 3), and combined organic layer was evaporated on rotary evaporator. Purification by silica gel column chromatography (mesh 100-200) using EtOAc-hexane (2: 98 to 15: 85) as mobile phase gave 3-acetylindole as a brick red solid (118 mg, 95% yield). The product was characterized by comparison of TLC of the product (Rf 0.5 in EtOAc: n-hexane- 1: 1) with commercially available sample (CAS Number 703-80-0; Sigma Aldrich: Catalog no. A16807). It was also confirmed by comparison of NMR data with literature values (Guchhait, S. K.; Kashyap, M.; Kamble, H. J. Org. Chem. 2011, 76, 4753-4758. http://dx.doi.org/10.1021/jo200561f)

3-Acetylindole: Brick red solid, m. p. 188-190 °C;
¹H NMR (CD₃OD, 400 MHz): δ 8.21 (s, 1H), 8.13 (s, 1H), 7.44-7.42 (m, 1H), 7.24-7.17 (m, 2H), 2.51 (s, 3H);
HRMS: m/z 160.0774 calcd for C₁₀H₉NO + H⁺ (160.0757).
IR (CHCl₃): 3156, 2926, 1613, 1578, 1524, 1493, 1459, 1440, 1420, 1315, 1242, 1177, 1025 cm^-1;

MacKay, J. A.; Bishop, R. L.; Rawal, V. H. Org. Lett., 2005, 7, 3421-3424. http://dx.doi.org/10.1021/ol051043t