Imidazole → N-Boc-5-Iodo-D-norvaline tert-butyl ester

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Reaction Steps

A solution of the title E compound, (2R)-(t-butyioxycarbonylamino)-5-hydroxy-pentanoic acid t-butyl ester (9.12 g, 31.5 mmol), imidazole (3.22 g, 47.3 mmol) and triphenylphosphine (12.40 g, 47.3 mmol) in 300 mL of THF is treated portionwise over 5 min with iodine (9.60 g, 37.8 mmol) at RT. After 2 h, the mixture is filtered and concentrated. The residue is first filtrated though silica gel (eluant; ethyl acetate) then purified by chomatography on silica gel (eluant; 10% ethyl acetate in hexane) affording 9.05 g (72%) of (2R)-(t-butyloxycarbonylamino)-5-iodopentanoic acid t-butyl ester as a colorless oil: NMR(CDCl3) 1.42 (s, 9H), 1.46 (s, 9H), 1.65-1.95 (m, 4H), 3.14-3.28 (m, 2H), 4.19-4.26 (m, 1H), 5.06 (br d, 1H, J=7.4); IR 1712, 1500, 1155; ESI-MS 400 (M++1).

Provenance & Evidence