7-Isopropoxy-6-methoxy-2-methylbenzo[b]thiophene → 7-Hydroxy-6-methoxy-2-methyl-benzo[b]thiophene

Participants

Reaction Steps

To a mixture of the product of Step D (0.033 g; 0.0941 mmol) in CH2Cl2 (1 ml) TiCl4 (0.02 ml; 0.182 mmol) was added at room temperature under N2. After stirring for 10 min at room temperature, the mixture was diluted to 15 ml with CH2Cl2 and quenched with H2O (5 ml) and the organic phase was dried over anhydrous MgSO4, filtered and filtrate evaporated to dryness under reduced pressure to give 7-hydroxy-6-methoxy-2-methyl-benzo[b]thiophene (0.0256 g; 100%). This was diluted to 1.ml with CH2Cl2 and tosyl chloride (0.03 g; 0.158 mmol), followed by triethylamine 0.022 ml; 0.158 mmol) of were added to it. The resulting mixture was stirred for 1 h at room temperature, washed with H2O, dried over anhydrous MgSO4, filtered and filtrate evaporated to dryness under reduced pressure. The residue was purified by crystallization from hexane/ethyl acetate mixture (9.5:0.5) to give the title compound (0.035 g; 68%), as creamy crystals. 1H-NMR (CDCl3) 2.45 (s, 3H); 2.48 (s, 3H); 3.63 (s, 3H); 6.83 (s, 1H); 7.32 (d, 2H, J=8.27 Hz); 7.43 (d, 1H, J=8.62 Hz), 7.87 (d, 2H, J=8.62 Hz).

Provenance & Evidence