Keto-pantoyllactone → D-Pantolactone

Participants

Reaction Steps

A 500 ml steel autoclave was loaded in a glove box (O2 -content less than 1 ppm) with 40.0 g (0.31 mol) of ketopantolactone, 210 ml of toluene, 180.6 mg (0.389 mmol) of [Rh(COD)2 ]PF6, 215.2 mg (0.389 mmol) of BPPM and 176.4 mg (0.389 mmol) of tetrabutylammonium pentafluorobenzoate. The hydrogenation was carried out at a constant pressure of 40 bar of H2, at 30° C. and with intensive stirring. By virtue of the exothermic reaction the temperature rose to 40° C. After a hydrogenation time of 3 hours the mixture was worked-up as described in Example 2. Pure (R)-pantolactone was obtained. [α]D20 =-45.8°. Optical purity 88.8%.

Provenance & Evidence