Trifluoroacetic acid → (Hydroxy-(3,4,5-trimethoxy-phenyl)-methyl]-phosphonic acid dimethyl ester

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Reaction Conditions

Reaction Steps

A round-bottom flask equipped with thermometer, condenser and gas inlet was charged with methanol (150 mL) and sodium methoxide (1.074 g, 20 mmol) and cooled to 0° C. under nitrogen protection. To a stirred solution were added subsequently dimethyl phosphate (19.52 g, 0.177 mol) and 3,4,5-trimethoxybenzaldehyde (30 g, 0.153 mol). A resulted solution was heated at 50° C. for 1 hour, cooled down to r.t. and treated with trifluoroacetic acid (4.6 ml). The mixture was concentrated under reduced pressure, the residue dissolved in EtOAc (300 mL), washed once with 18% brine, then once with saturated brine, dried over sodium sulfate. The filtered solution was concentrated until precipitation started. To the resulted suspension 1:1 mixture of t-butylmethyl ether and heptane was added (50 mL). Solid was filtered out, washed with two portions (20 mL) of the same solvent mixture and vacuum-dried to give 41.2 g (88%) of 1, LC purity 99.4% (AUC), m.p. 103-104° C.

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