2,3-Dihydroxybutanedioic Acid → Diisopropylether ethyl acetate

Participants

Reaction Steps

6.1 g of crude N-(N-carbobenzoxy-DL-α-hydroxyalanyl)-L-phenylalanyl-L-proline p-nitrophenyl ester obtained in step hi), hii) or hiii) below, in 300 ml acetone, is treated with a 10% (w/v) potassium tartrate solution (having pH = 7.9). The reaction mixture is stirred for 18 hours at room temperature, and worked up by the addition of 10% (w/v) tartaric acid solution until the reaction mixture is at a pH of 5 and extraction with methylene chloride. The product obtained on concentration is crystallized from ethyl acetate or an ethyl acetate/diisopropyl ether mixture (3:1; v/v) yielding, after drying at 90° in a high vacuum, the aci-form of the title compound (M.Pt. 206°-208°; decomposition); [α]D20 = -28° (c = 0.5 in CH3OH).

Provenance & Evidence