HCID 67646660, compound → HCID 86751149, compound

Participants

Reaction Steps

A mixture of 4 g of ethyl 5-BOC-amino-2-benzoyloxy-2-ethoxycarbonyl-pentanoate and 2 g of K2 CO3 in 40 ml of anhydrous methanol, cooled to 0°-5° C., is stirred for 1 h. After filtration of the potassium carbonate excess, the solution is acidified to pH 6 with 2N HCl and filtered from the salts which separate. Solvent is evaporated off under vacuum and the residue is partitioned between cold water and ethyl acetate. The organic phase is washed repeatedly with a 5% K2CO3 cold solution and with water to neutrality, dried over sodium sulfate and evaporated to dryness. The residue (3 g) is eluted, purified on 30 g of silica gel, eluent hexane-ethyl acetate from 95:5 to 80:20, to give methyl benzoate and 1.8 g of methyl 5-BOC-amino-2-hydroxy-2-methoxycarbonyl-pentanoate (oil). TLC (4:6 AcOEt-hexane) Rf=0.19 I.R.: (--OH and --NH--3400 cm-1 broad peak) (C=O 1730 cm-1 broad peak) NMR (CDCl3 /TMS): (δ) 1.45 s; 1.45-1.6 m; 2.0-2.1 m; 3.05-3.2 q; 3.8 s; 4.6 s. By acidification of the basic extracts with 20% KHSO4 and subsequent extraction with ethyl acetate, 0.17 g of 5-BOC-amino-2-hydroxy-2-methoxycarbonyl-pentanoic acid are obtained (oil) TLC (3:1:1 nBuOH-AcOH-H2O) Rf=0.54

Provenance & Evidence