2-Azetidinecarboxylic acid, (S)- → AzeOH D-tartrate

Participants

Reaction Conditions

Reaction Steps

50 g of a mother liquor containing enantiomerically-enriched AzeOH containing 16 g (68% e.e.) of D-AzeOH (prepared in accordance with Example 1) was concentrated under vacuum to give a viscous oil, which was further dewatered by azeotropic distillation with isopropanol. Acetic acid (72 mL) was added to the concentrated residue. The mixture was heated to 95° C. and D-tartaric acid (25 g) and caproic aldehyde (2.8 g) were added. The mixture was seeded with L-AzeOH-D-tartrate, kept at 95-100° C. for 3 hours and then gradually cooled to 0° C. The crystalline product was filtered, washed and dried at 60° C. under vacuum to yield 29.3 g of L-AzeOH-D-tartrate with a d.e. of 94.6%. Recrystallisation of 28 g of the diastereomeric salt from ethanol:water (140 mL; 1.25:1.0) yielded 21.4 g of L-AzeOH-D-tartrate with a d.e. of 100%.

Provenance & Evidence