Water → t-Butyl 2-(benzyloxycarbonyl)amino-3-aminopropionate

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反応手順

A solution of 2-(S)-(benzyloxycarbonyl)amino-3-aminopropionate (Fluka) (5.25 g, 22 mmol) in dioxane (75 mL) and conc. sulfuric acid (9 mL) was cooled to 0° C. and treated with 100 mL isobutylene in a Fisher Porter high pressure apparatus. The reaction was allowed to warm to room temperature and was stirred for 24 h. The reaction was vented, then poured into water (200 mL) to give an acidic solution that was extracted with ether (2×50 mL). The aqueous layer was carefully basified with conc. NaOH to pH 11-12 and extracted with 3×150 mL EtOAc. The EtOAc was removed in vacuo and the residue was azeotroped with toluene and dried under vacuum to give 4-1 as an oil. Rf (5% MeOH/CHCl3 saturated with NH3) 0.31. 1H NMR (400 MHz, CDCl3) δ7.3 (m, 5H), 5.6 (bs, 1H), 5.1 (s, 2H), 4.22 (bs, 1H), 3.05 (m, 2H), 1.45 (s, 9H), 1.4-1.2 (b, 2H).

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