2-benzofurancarboxylic acid ethyl ester

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

Procedure: The reaction of 2-ethoxycarbonylbenzofurane (27.40 g) with diisobutylaluminum hydride was carried out in the manner similar to that described in Reference Example 3 to give the titled compound (16.91 g) as a colorless oil. This compound was used without further purification.

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

Procedure: A mixture of salicylaldehyde (53.10 g), K2CO3 (97 g) and ethyl bromoacetate (73.30 g) in ethanol (200 ml) was refluxed for 6 hours. The reaction mixture was diluted with ethyl acetate, washed with water, 1N NaOH and brine, dried and concentrated to give the titled compound (27.40 g) as a colorless oil was refluxed for 6 hours washed with water, 1N NaOH and brine dried concentrated

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

Procedure: A mixture of salicylaldehyde (53.10 g), K2CO3 (97 g) and ethyl bromoacetate (73.30 g) in ethanol (200 ml) was refluxed for 6 hours. The reaction mixture was diluted with ethyl acetate, washed with water, 1N NaOH and brine, dried and concentrated to give the titled compound (27.40 g) as a colorless oil was refluxed for 6 hours washed with water, 1N NaOH and brine dried concentrated

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

Procedure: A 3-neck round bottomed flask equipped with a mechanical stirrer, a dropping funnel, a gas inlet tube, and a thermometer is charged with 24.4 g (0.2 mol) of salicyl aldehyde (Aldrich) and 800 ml of THF-EtOH (19:1) under a nitrogen atmosphere. To this solution 150 ml (0.24 mol) of potassium t-butoxide in THF (1.6M) is added dropwise over 20 min at room temperature. A milky yellow precipitate is formed during the addition. The mixture is stirred at room temperature for one hr. A solution of 57.4 g (0.24 mol) of diethyl bromomalonate (Aldrich) in 20 ml of THF is added dropwise over 10 min. The mixture becomes grayish in color. After stirring for one hr at room temperature, another portion of potassium t-butoxide in THF (150 ml, 0.24 mol) is added dropwise over 40 min at room temperature. TLC shows no starting material remaining after an additional 40 min of stirring. The mixture is poured into 500 ml of brine mixed with crushed ice and extracted twice with ethyl acetate (1 L). The organic phase is washed with brine and dried over anhydrous magnesium sulfate. Filtration and concentration affords a deep brown oil. Vacuum distillation affords pure ethyl benzofuran-2-carboxylate (boiling point 88°-91° C./0.03 mm, 32.5 g, 85%). A 3-neck round bottomed flask equipped with a mechanical stirrer, a dropping funnel, a gas inlet tube A milky yellow precipitate is formed during the addition After stirring for one hr at room temperature remaining after an additional 40 min of stirring mixed with crushed ice extracted twice with ethyl acetate (1 L) The organic phase is washed with brine dried over anhydrous magnesium sulfate Filtration and concentration affords a deep brown oil Vacuum distillation

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

Procedure: A 3-neck round bottomed flask equipped with a mechanical stirrer, a dropping funnel, a gas inlet tube, and a thermometer is charged with 24.4 g (0.2 mol) of salicyl aldehyde (Aldrich) and 800 ml of THF-EtOH (19:1) under a nitrogen atmosphere. To this solution 150 ml (0.24 mol) of potassium t-butoxide in THF (1.6 M) is added dropwise over 20 min at room temperature. A milky yellow precipitate is formed during the addition. The mixture is stirred at room temperature for one hr. A solution of 57.4 g (0.24 mol) of diethyl bromomalonate (Aldrich) in 20 ml of THF is added dropwise over 10 min. The mixture becomes grayish in color. After stirring for one hr at room temperature, another portion of potassium t-butoxide in THF (150 ml, 0.24 mol) is added dropwise over 40 min at room temperature. TLC shows no starting material remaining after an additional 40 min of stirring. The mixture is poured into 500 ml of brine mixed with crushed ice and extracted twice with ethyl acetate (1 L). The organic phase is washed with brine and dried over anhydrous magnesium sulfate. Filtration and concentration affords a deep brown oil. Vacuum distillation affords pure ethyl benzofuran-2-carboxylate (boiling point 88°-91° C./0.03 mm, 32.5 g, 85%.) A 3-neck round bottomed flask equipped with a mechanical stirrer, a dropping funnel, a gas inlet tube A milky yellow precipitate is formed during the addition After stirring for one hr at room temperature remaining after an additional 40 min of stirring mixed with crushed ice extracted twice with ethyl acetate (1 L) The organic phase is washed with brine dried over anhydrous magnesium sulfate Filtration and concentration affords a deep brown oil Vacuum distillation