4-ethoxy-2,3-dihydroxybenzaldehyde

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of boron trichloride (3.34 mL, 3.34 mmol 1M in DCM, 1 eq) was added dropwise to a solution of 33 (0.80 g, 3.34 mmol) in DCM at room temperature. The reaction mixture was stirred for 2 hours at this temperature then a further one equivalent of boron trichloride (3.34 mL, 3.34 mmol, 1M in DCM) was added and the reaction mixture was stirred at room temperature overnight. The reaction mixture was cooled to 0° C. and saturated NaHCO3 aq. was added, then made acidic by the dropwise addition of conc. HCl. The reaction mixture was extracted with TBME (3×) and the organic phase was dried (Na2SO4) and concentrated in vacuo to give the crude product (1.4 g). Purification by column chromatography (SiO2 1:2 EtOAc:cyclohexane) gave 34 compound (0.46 g, 76%): the reaction mixture was stirred at room temperature overnight The reaction mixture was extracted with TBME (3×) the organic phase was dried (Na2SO4) concentrated in vacuo to give the crude product (1.4 g) Purification by column chromatography (SiO2 1:2 EtOAc:cyclohexane)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of boron trichloride (3.34 mL, 3.34 mmol 1M in DCM, 1 eq) was added dropwise to a solution of 33 (0.80 g, 3.34 mmol) in DCM at room temperature. The reaction mixture was stirred for 2 hours at this temperature then a further one equivalent of boron trichloride (3.34 mL, 3.34 mmol, 1M in DCM) was added and the reaction mixture was stirred at room temperature overnight. The reaction mixture was cooled to 0° C. and saturated NaHCO3 aq. was added, then made acidic by the dropwise addition of conc. HCl. The reaction mixture was extracted with TBME (3×) and the organic phase was dried (Na2SO4) and concentrated in vacuo to give the crude product (1.4 g). Purification by column chromatography (SiO2 1:2 EtOAc:cyclohexane) gave 34 compound (0.46 g, 76%): the reaction mixture was stirred at room temperature overnight The reaction mixture was extracted with TBME (3×) the organic phase was dried (Na2SO4) concentrated in vacuo to give the crude product (1.4 g) Purification by column chromatography (SiO2 1:2 EtOAc:cyclohexane)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of boron trichloride (3.34 mL, 3.34 mmol 1M in DCM, 1 eq) was added dropwise to a solution of 33 (0.80 g, 3.34 mmol) in DCM at room temperature. The reaction mixture was stirred for 2 hours at this temperature then a further one equivalent of boron trichloride (3.34 mL, 3.34 mmol, 1M in DCM) was added and the reaction mixture was stirred at room temperature overnight. The reaction mixture was cooled to 0° C. and saturated NaHCO3 aq. was added, then made acidic by the dropwise addition of conc. HCl. The reaction mixture was extracted with TBME (3×) and the organic phase was dried (Na2SO4) and concentrated in vacuo to give the crude product (1.4 g). Purification by column chromatography (SiO2 1:2 EtOAc:cyclohexane) gave 34 compound (0.46 g, 76%): the reaction mixture was stirred at room temperature overnight The reaction mixture was extracted with TBME (3×) the organic phase was dried (Na2SO4) concentrated in vacuo to give the crude product (1.4 g) Purification by column chromatography (SiO2 1:2 EtOAc:cyclohexane)