Imidazole → Benzyl (S)-2-(Boc-amino)-4-iodobutanoate

Participants

Reaction Steps

To a solution of triphenylphosphine (734 mg, 2.80 mmol) and imidazole (191 mg, 2.80 mmol) in CH2Cl2 (10 ml) at rt was added iodine (711 mg, 2.80 mmol) portionwise over 5 min. The mixture first turned yellow, then brown and developed precipitate. The mixture was stirred at rt until no pieces of iodine were visible (approx. 5 min.). A solution of alcohol from step (38b) (721 mg, 2.33 mmol) in CH2Cl2 (5 ml) was added and the resulting mixture was stirred at rt for 1 h. The reaction was filtered and concentrated in vacuo. Purification by flash chromatography (silica, 0-25% EtOAc/Hexane) gave 2-tert-butoxycarbonylamino-4-iodo-butyric acid benzyl ester (430 mg, 44%) as a slightly yellow oil: 1H NMR (500 MHz, Methanol-D) δ 7.24-7.42 (m, 5 H), 5.07-5.25 (m, 2 H), 4.16-4.31 (m, 1 H), 3.12-3.29 (m, 2 H), 2.01-2.35 (m, 2 H), 1.42 (s, 9 H). LC-MS (Method A, retention time: 1.71 min), MS m/z 420 (M++1).

Provenance & Evidence