Keto-pantoyllactone → D-Pantolactone

Beteiligte Stoffe

Reaktionsschritte

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, 237.3 mg (0.389 mmol) of mCH3 --BPPM and 138.3 mg (0.389 mmol) of tetrabutylammonium trifluoroacetate. 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 55° C. A conversion of above 99% was achieved after 1.2 hours. After a total hydrogenation time of 2 hours the mixture was worked-up as described in Example 2. Pure (R)-pantolactone was obtained. [α]D20 =-46.0°. Optical purity 89.1%.

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