(+-)-Pantolactone → D-Pantolactone

Participants

Reaction Steps

The optically active bases (+)- and (-)-3-aminomethylpinane prove astonishingly stable in the course of the various stages of the process. In none of them are measurable quantities of by-products produced, so that when recycling the (+)- or (-)-3-aminomethylpinane and L-pantolactone for re-use, neither the 3-aminomethylpinane nor the racemized pantolactone has to be subjected to special purification treatments. The optical purity of the D-pantolactone obtained in accordance with the process corresponds, within the limits of analytical error, to the data given in Example 3 for the product obtained from a first separation, even after the optically active base used, the racemized pantolactone left in each case, and the solvent used, have been recycled 20 times; this shows that special purification treatments are not necessary. The new process gives optically pure D-(-)-pantolactone in an overall yield of 90%, based on the DL-pantolactone employed.

Provenance & Evidence