Iodoethane → 2-Bromo-5-ethoxybenzaldehyde

Participants

Reaction Steps

2-Bromo-5-hydroxybenzaldehyde (0.96 g, 4.8 mmol) was dissolved in anhydrous DMSO (10 mL). Iodoethane (0.50 mL, 6.2 mmol) and Cs2CO3 (1.9 g, 6.3 mmol) were added and the mixture stirred at room temperature for 1.5 hours. Additional Cs2CO3 (1.45 g, 4.8 mmol) was added to the reaction mixture and then was stirred for 30 minutes. The reaction mixture was diluted with H2O and EtOAc and the layers were separated. Brine was added to the aqueous layer and it was extracted twice with EtOAc. The combined organics were washed with 1M NaOH twice and brine thrice, and then was dried over MgSO4. The solution was vacuum-filtered through Celite® and concentrated in vacuo to give 1.08 g of 2-bromo-5-ethoxybenzaldehyde. 2-Bromo-5-ethoxy-benzaldehyde (1.02 g, 4.45 mmol) was dissolved in anhydrous toluene (10 mL) under N2. Diethyl phosphite (0.57 mL, 4.4 mmol), then MgO (0.45 g, 11.2 mmol) was added and the N2 inlet was removed. The mixture was stirred at room temperature for 1.75 hours, and more diethyl phosphite (0.1 mL, 0.77 mmol) was then added. The mixture was stirred for an additional 2.75 hours, then diluted with EtOAc, H2O, and saturated aqueous NaHCO3. The layers were separated and the organic layer was washed with brine, dried over MgSO4, vacuum-filtered through Celite® and conc in vacuo to give 1.70 g of crude material. The product was used without purification. Diethyl(2-bromo-5-ethoxyphenyl)-(hydroxy)-methyl-phosphonate (1.13 g, 3.08 mmol) was dissolved in anhydrous dichloromethane (13 mL). Pyridinium chlorochromate (1.22 g, 4.6 mmol) was added and the mixture was stirred at room temperature for 17 hours at which time additional pyridinium chlorochromate (1.1 g, 5.1 mmol) was added. The mixture was stirred at room temperature for 3 hours, and then was refluxed for 45 minutes under a drying tube. The reaction was diluted with dichloromethane and washed with H2O and saturated aq. NaHCO3, dried over MgSO4, vacuum-filtered through Celite® and concentrated in vacuo. The product was chromatographed (EtOAc-hexanes) to give diethyl(2-bromo-5-ethoxyphenyl)-oxomethylphosphonate. The diethyl (2-bromo-5-ethoxyphenyl)oxo-methyl-phosphonate was reacted with DAST according to Example 80C to give diethyl (2-bromo-5-ethoxyphenyl)difluoromethylphosphonate. Compound 93 was synthesized according to procedures similar to those of Example 40 from this corresponding diethyl phosphonate. MS (ES-): m/z 329.0, 331.0 (M−H). 1H NMR: (DMSO-d6, 400 MHz) δ 7.56 (d, J=8.8, 1H), 7.11 (d, J=2.7, 1H), 6.97 (dd, J=2.7, 8.8, 1H), 4.01 (q, J=7.2, 2H), 1.30 (t, J=7.2, 3H).

Provenance & Evidence