Methyl iodide → (S)-4-Benzyl 1-methyl 2-((tert-butoxycarbonyl)amino)succinate

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Reaction Conditions

Reaction Steps

Boc-Asp(OBn)-OH 2.4 g (1 equiv, 7.45 mmol) was dissolved in 17 mL of dry DMF in a 100 mL round-bottom flask. Finely ground K2CO3 (1.5 g, 11 mmol) was added to the solution to form a suspension. The mixture was cooled to 0° C. in an ice-bath over five minutes. MeI (1 mL, 15 mmol) was then added to the mixture over 20 seconds under a positive flow of nitrogen. A yellow color developed within 30 min. The resulting mixture was stirred for 3 hours. The ice-bath was removed and 25 mL of water were added and the mixture left standing at room temperature 2 hours. The mixture was then treated with 30 mL of water and extracted with 3×25 mL AcOEt. The organics were washed with saturated NaHCO3 1×, brine 3×, dried over Na2SO4 filtered and concentrated to yield a yellow oil. This material was passed through a short silica column (eluting w/ AcOEt), after concentration of the pure fractions 2.42 g of Boc-Asp(OBn)-OMe as a yellow oil was obtained (98% yield). 1H NMR (DMSO d6, 500 mHz): δ 7.36 (m, 5H), 5.10 (s, 2H), 4.40 (q, 1H), 3.6 (s, 3H), 2.80 (dd, 1H), 2.72 (dd, 1H), 1.38 (s, 9H). LCMS (C18, 2-98% CH3CN in 0.1% TFA/H2O over 6 min); Calculated mass for C17H23NO6 (M+H)+ 338.23. found by LC-MS 338.2.

Provenance & Evidence