Hydrochloric Acid → p-Toluenesulfonic acid

Participants

Reaction Conditions

Reaction Steps

To 20 mL of methanol, 2.00 g (prepared to be 7.61 mmol) of the hydrochloric acid salt and 1.61 g (8.46 mmol, 1.11 eq) of p-toluenesulfonic acid monohydrate were added, and dissolving under heating was made at 40 to 50° C., followed by making concentration under reduced pressure and drying under vacuum. To the residue, 14 mL of isopropanol and 8 mL of n-heptane were added, and then dissolving was made under heating at 90° C., followed by gradually lowering the temperature to 0° C. The precipitated crystal was filtered, and washed with a small amount of n-heptane, followed by being subjected to drying under vacuum, thereby obtaining 1.71 g of p-toluenesulfonic acid salt (refined product) of α-trifluoromethyl-β-substituted-β-amino acids represented by the above-mentioned formula. The total yield from α-trifluoromethyl-β-substituted-α,β-unsaturated esters was 60%. The diastereomer ratio was syn-body:anti-body=>98:2 according to 1H- and 19F-NMR analyses.

Provenance & Evidence