Bis-(1H-imidazol-2-YL)-methanone → (S)-2-Benzyloxycarbonylamino-4-oxo-hexanedioic acid 6-tert-butyl ester 1-methyl ester

Beteiligte Stoffe

Reaktionsschritte

To a solution of N-CBZ L-aspartic acid 1-methyl ester (1.00 g, 3.55 mmol) in dry tetrahydrofuran (17 mL) is added carbonyl diimidazole (634.1 mg, 3.91 mmol). The mixture is stirred at room temperature for 6 hr then the magnesium salt of mono-tert butyl malonate (1.339 g, 3.91 mmol) (prepared according to Angew. Chem. Int. Ed. Engl. 1979, 18(1), 72-74) is added. The mixture is stirred at room temperature for another 20 h, then concentrated in vacuum. The residue is partitioned between ether (60 mL) and 0.5 N HCl (60 mL). The organic layer is washed with saturated NaHCO3 solution (50 mL) then dried over magnesium sulfate and concentrated in vacuum. The residue is purified over 35 g of silica gel, eluted with EtOAc:Heptane (1:1) to afford (S)-2-Benzyloxycarbonylamino-4-oxo-hexanedioic acid 6-tert-butyl ester 1-methyl ester (1.17 g, 87%).

Herkunft & Nachweise