Reaktion #1197322

Reaktionsgleichung

propionaldehyde

L-menthoxyacetyl chloride

PPh3

CH3OH

→

L-menthoxyacetic acid

Lösungsmittel

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeA 70 mL stainless steel high pressure reactor fitted with a Pyrex glass liner and magnetic stir bar
2. 2
   SonstigeThe reactor is sealed
3. 3
   SonstigeThe product mixture, isolated
4. 4
   Sonstigeafter removal of gas from the reactor vessel
5. 5
   workup.ADDITIONa diastereomeric mixture of methyl L-menthoxyacetyl-L-2-hydroxybutyrate and methyl L-menthoxyacetyl-D-2-hydroxybutyrate
6. 6
   SonstigeThe diastereomers are separated by preparative gas chromatography
7. 7
   workup.WAITEach diastereomer is hydrolyzed separately by treatment with 2N HCl (aq) for 2 hours at 100° C.

Vorschrift

1-Propenyl L-menthoxyacetate is prepared from propionaldehyde, L-menthoxyacetyl chloride, and pyridine catalyst. A 70 mL stainless steel high pressure reactor fitted with a Pyrex glass liner and magnetic stir bar is charged with THF (5 mL), PPh3)2PdCl2 (0.05 mmol), CH3OH (0.5 mmol), and 1-propenyl L-menthoxyacetate (0.5 mmol). The reactor is sealed, pressurized to 1000 psig with CO, and stirred for 24 hours at 100° C. The product mixture, isolated after removal of gas from the reactor vessel, contains a diastereomeric mixture of methyl L-menthoxyacetyl-L-2-hydroxybutyrate and methyl L-menthoxyacetyl-D-2-hydroxybutyrate. The diastereomers are separated by preparative gas chromatography using an SE-30 liquid phase column. Each diastereomer is hydrolyzed separately by treatment with 2N HCl (aq) for 2 hours at 100° C. to give pure L- and D-2-hydroxybutyric acid, methanol, and L-menthoxyacetic acid.

Quelle