反应详情

1-Hydroxybenzotriazole (4.05 g) was added to a solution of 4-nitrophenyl acetic acid (5.4 g) in dimethylformamide (75 ml). L-Glutamic acid di tert-butyl ester (7.77 g) and then dicyclohexylcarbodiimide (6.2 g) were added to the mixture. The mixture was then stirred for 18 hr at ambient temperature. The mixture was filtered and the filtrate washed with saturated sodium bicarbonate solution, water and 0.5 m hydrochloric acid and then dried and evaporated to dryness. The residue was chromatographed on silica gel by eluting with hexane/ethyl acetate (2:1) to give di t-butyl 4-nitrobenzylcarbonyl-L-glutamate as an oil 9.7 g (77%). NMR: 8.2(d)2H; 7.45(d)2H; 6.45(d)1H; 4.45(m)1H; 3.15(s)2H; 2.1(m)4H; 1.4(d)9H; 1.35(s)9H.

1. filtrationThe mixture was filtered
2. washthe filtrate washed with saturated sodium bicarbonate solution, water and 0.5 m hydrochloric acid
3. customdried
4. customevaporated to dryness
5. customThe residue was chromatographed on silica gel
6. washby eluting with hexane/ethyl acetate (2:1)