Pyridine → (s)-3-(2-Benzyloxybenzenesulfonylamino)-4,4-diethoxy-butyric acid tert-butyl ester

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Reaction Steps

2-Benzyloxy-benzenesulfonyl chloride (see Example 23, step 1) (1.7 g, 6 mmol) and (S)-3-amino-4,4-diethoxy-butyric acid tert-butyl ester (see Example 93) (1.5 g, 6 mmol) and pyridine (1.9 g, 30 mmol) were dissolved in chloroform (150 mL) and stirred at room temperature for 3 days. The reaction was diluted with ethyl acetate (500 mL) and washed with 5% citric acid, sat. sodium bicarbonate, and sat. sodium chloride. The organic layer was then dried over anhydrous sodium sulfate, filtered, and concentrated. Purification by flash chromatography (SiO2, hexane:ethyl acetate, 8:1, then 4:1) gave the desired product (2.7 g, 91%) as a colorless oil. 1H NMR (400 MHz) CDCl3 δ 7.92 (m, 1H), 7.52 (d, 2H), 7.47 (t, 1H), 7.40 (t, 2H), 7.34 (d, 1H), 7.04 (t, 2H), 5.61 (d, 1H), 5.23 (q, 2H), 4.30 (d, 1H), 3.77 (m, 1H), 3.47 (m, 2H), 3.36 (m, 1H), 3.15 (m, 1H), 2.45 (t, 2H), 1.37 (s, 9H), 1.02 (t, 3H), 0.92 (t, 3H).

Provenance & Evidence