ethyl 5-hydroxy-1-benzofuran-2-carboxylate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Starting with 2.41 g (11.69 mmol) of 5-hydroxy-2-benzofuran-carboxylic acid ethyl ester, and 8.06 (35.06 mmol) of 1,5-dibromopentane, the title compound (3.03 g; 73%) was obtained as a white solid, mp 31° C., using the procedure of example 21.

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a mixture of aluminum chloride (6.3 g, 47.7 mmol) and ethanethiol (4.5 g, 72.9 mmol) in dichloromethane (81 mL) at 0° C. was added ethyl 5-methoxybenzofuran-2-carboxylate (3.0 g, 13.6 mmol). After stirring for 16 h at room temperature, the mixture was poured into water, acidified with 3N HCl and extracted with dichloromethane (2x). The organic layers were combined, washed with brine, collected, dried (MgSO4), filtered and concentrated. The residue was purified by column chromatography (silica gel, ethyl acetate/hexane) to yield the title compound as a white solid (2.16 g, 77%). 1H NMR (400 MHz, CDCl3) δ 7.45 (m, 2H), 7.08 (m, 1H), 7.02 (m, 1H), 5.35 (s b, 1H), 4.44 (q, 2H), 1.42 (t, 3H). extracted with dichloromethane (2x) washed with brine collected dried (MgSO4) filtered concentrated The residue was purified by column chromatography (silica gel, ethyl acetate/hexane)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: [3-Methyl-4-(1-pyridin-3-ylmethyl-piperidin-3-ylmethoxy)-benzofuran-2-yl]-methanol (107 mg), 5-hydroxybenzofuran-2-carboxylic acid ethyl ester (60 mg), triphenylphosphine (100 mg) and azodicarboxylic acid diethyl ester (70 μl) were dissolved in THF (7 ml). The solution was stirred overnight at room temperature. A white precipitate separated out. The precipitate was filtered out and the filtrate was evaporated to dryness. The residue was separated by silica gel column chromatography developed by dichloromethane-methanol to give 5-[3-methyl-4-(1-pyridin-3-ylmethyl-piperidin-3-ylmethoxy)-benzofuran-2-ylmethoxy]-benzofuran-2-carboxylic acid ethyl ester (48 mg) as a colorless oil. FAB-MS: m/z 555 (MH+); 1H-NMR (CDCl3): δ 1.25-2.23 (7H, m), 1.43 (3H, t, J=7 Hz), 2.24 (3H, s), 2.78 (1H, m), 2.95 (1H, m), 3.47 (1H, d, J=13 Hz), 3.57 (1H, d, J=13 Hz), 3.89 (2H, m), 4.44 (2H, q, J=7 Hz), 5.10 (2H, s), 6.55 (1H, d, J=8 Hz), 7.04 (1H, d, J=8 Hz), 7.14 (1H, dd, J1=9 Hz, J2=2 Hz), 7.23 (3H, m), 7.47 (1H, m), 7.48 (1H, s), 7.66 (1H, br d, J=7 Hz), 8.48 (1H, br d, J=5 Hz), 8.53 (1H, br s). A white precipitate separated out The precipitate was filtered out the filtrate was evaporated to dryness The residue was separated by silica gel column chromatography

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Triphenyl phosphine polymer bound (8.96 mmol) was suspended in anhydrous dichloromethane (20 ml) then diisopropyl azodicarboxylate (7.76 mmol) was added and the mixture was stirred for 15 minutes at room temperature. Then ethyl 5-hydroxybenzofuran carboxylate (5.97 mmol) was added over 5 minutes followed by the addition of 4-N-boc-3-morpholinecarboxylic acid (5.97 mmol) over 5 minutes too. The mixture was stirred at room temperature over night. The solvent was evaporated under vacuo and the residue purified by flash chromatography to obtain ethyl 5-(4-Boc-morpholin-2-ylmethoxy)-benzofuran-2-carboxylate: m/z=406 in MS ES+, as clear oil. The mixture was stirred at room temperature over night The solvent was evaporated under vacuo the residue purified by flash chromatography

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Ethyl 5-methoxybenzofuran carboxylate (22.7 mmol) was dissolved in dichlormethane (20 ml) and a 1.0 M solution of boron tribromide methyl sulphide complex in dichloromethane (68.1 mmol) was added. The mixture was heated at reflux over night The solvent was evaporated under vacuo and the residue purified by flash chromatography to obtain ethyl 5-hydroxybenzofuran carboxylate as a white solid. The mixture was heated at reflux over night The solvent was evaporated under vacuo the residue purified by flash chromatography

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Ethyl 5-methoxybenzofuran carboxylate (22.7 mmol) was dissolved in dichlormethane (20 ml) and a 1.0 M solution of boron tribromide methyl sulphide complex in dichloromethane (68.1 mmol) was added. The mixture was heated at reflux over night The solvent was evaporated under vacuo and the residue purified by flash chromatography to obtain ethyl 5-hydroxybenzofuran carboxylate as a white solid. The mixture was heated at reflux over night The solvent was evaporated under vacuo the residue purified by flash chromatography