(-)-Mandelic acid → (R)-1-(3-Methoxyphenyl)ethylamine

Participants

Reaction Steps

A solution of 14.0 g (92.0 mmol) of (R)-(-)-mandelic acid (Aldrich, 99+%), 14.0 g (92.7 mmol) of (±) 3-methoxy-α-methylbenzylamine and 500 mL of isopropanol was brought to reflux and gravity filtered while hot. The solution was then seeded at 50° C. with diastereomerically-pure seeds. After cooling to room temperature, the mixture was filtered to afford 10.9 g of a fluffy, white solid. This was recrystallized from 500 mL of isopropanol. The solids were collected then partitioned between ethyl acetate and saturated Na2CO3. The organics were washed with saturated NaCl, dried with Na2SO4, and concentrated to afford 5.8 g (83%) of a yellow oil. NMR analysis of the derived camphorsulfonamide (FIG. 6) indicated that the chemical is enantiomerically pure, to the limits of detection of NMR. This oil was distilled, b.p. 118°-120° C. at aspirator pressure, α!D =3.8° (c+1 in 2N HCl). Preliminary results suggest that this compound may form a carbonate upon exposure to air. It is therefore recommended that the chemical be stored under an inert atmosphere.

Provenance & Evidence