Boc-L-beta-homoglutamic acid 6-benzyl ester

128135-31-9

218943-30-7

The general procedure for the synthesis of (S)-6-(benzyloxy)-3-((tert-butoxycarbonyl)amino)-6-oxohexanoic acid from 6-benzyl 3-(tert-butoxycarbonyl)amino)adipate (6) was as follows: diazoxide (5) (3.00 g, 8.30 mmol) was dissolved in a 5:1 solvent mix of THF/H2O (60 ml), cooled in an ice bath, and aluminum foil was used to wrap the flask to avoid light. Subsequently, silver trifluoroacetate (0.37 g, 1.66 mmol) was added and NMM (2.28 ml, 20.75 mmol) was added dropwise. The reaction mixture was reacted under stirring for 4.5 hours and gradually warmed up to room temperature. After completion of the reaction, THF was removed by evaporation, 1N KHSO4 aqueous solution (40 ml) was added and the precipitate was removed by filtration. The aqueous phase was extracted with ethyl acetate and the organic phase was washed twice with 1N KHSO4 aqueous solution, dried over MgSO4 and then evaporated in vacuum to remove the solvent. The yellow crude product obtained was ground with ether to give the target compound as a white solid (2.17 g, 74% yield).1H NMR (CDCl3, 300 MHz) δ: 7.42-7.31 (m, 5H), 5.13 (s, 2H), 4.00 (m, 1H), 4.03-3.90 (m, 1H), 2.70-2.56 (m, 2H) , 2.54-2.40 (m, 2H), 1.98-1.85 (m, 2H), 1.45 (s, 9H).