91% |
Stage #1: 2-phenylthiophene With n-butyllithium; N,N,N,N,-tetramethylethylenediamine In tetrahydrofuran; hexane at -78 - 20℃; for 0.5h; Inert atmosphere;
Stage #2: With iodine In tetrahydrofuran; hexane at -78 - 20℃; Inert atmosphere; |
Synthesis of 2-Phenyl-5-iodothiophene (28) [CAS Reg. No. 13781-37-8]
To a cold (-78 °C) solution of n-BuLi in hexanes (0.63 mL, 1.5 mmol) and TMEDA (0.22 mL, 1.5 mmol) was added a THF solution (5 mL) of 2-phenylthiophene (27) (0.250 g, 1.5 mmol) and the mixture was allowed to reach r.t. in about 30 min. The reaction mixture was cooledto -78 °C and treated with a THF solution (10 mL) of iodine (0.436 g,1.72 mmol) and allowed to warm to r.t. The mixture was treated with an aqueous solution (10 mL) of Na2S2O3 (1.56 g), extracted with ether, and dried over MgSO4. The crude material was filtered through a small pad of silica gel and concentrated in vacuo to obtain 28. Yield: 0.404 g (91%); brownish solid.1H NMR (CDCl3, 400 MHz): = 7.53 (m, 2 H), 7.38 (br dd, J = 7.8,7.2 Hz, 2 H), 7.30 (dddd, J = 7.4, 7.4, 1.2, 1.2 Hz, 1 H), 7.22 (d, J =3.8 Hz, 1 H), 6.98 (d, J = 3.8 Hz, 1 H).13C NMR (CDCl3, 100 MHz): = 150.4, 137.9, 133.6, 129.0, 128.0,125.8, 124.5, 72.3.MS (EI): m/z (%) = 39 (4), 51 (5), 63 (8), 79 (15), 102 (10), 115 (85), 127(5), 143 (10), 158 (8), 184 (3), 286 (100) [M]+, 288 (12) [M+2]+.HRMS (ESI, V+): m/z [M + H]+ calcd for C10H8SI: 286.9391; found:286.9394. |