Sulfuric acid magnesium salt (1:1) → (2S,9S)-7-Benzyl-2-[(tert-butoxycarbonyl)amino]-10-chloro-9-hydroxy-7-azadecanoic Acid, tert-Butyl Ester

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A mixture of Nε-benzyl-Nα-BOC-L-lysine t-butyl ester (24) (16.0 g, 40.76 mmol), CH3OH (40 ml), (S)-(+)-epichlorohydrin (4.17 g, 45.0 mmol) and anhydrous MgSO4 (5.33 g. 44.28 mmol) was stirred under N2 for three days. The solids were filtered off and washed with CH3OH. The filtrate was concentrated at room temperature to give a yellow oil. The resulting oil was purified by flash chromatography on silica gel (66% hexane/ethyl acetate) to give 13.23 g of (25) (77%) as a colorless oil. 1H NMR (C6D6) δ7.18 (m, 5H), 5.00 (br d, 1H), 4.40 (m, 1H), 3.62 (m, 1H), 3.40-3.10 (m, 4H), 2.20-2.00 (m, 4H), 1.63 (m, 1H), 1.40 (s, 9H), 1.31 (s, 9H), 1.20 (m, 2H). 13C NMR (C6D6) δ171.7, 155.2, 138.8, 128.8, 127.9, 127.0, 80.8, 78.8, 67.7, 58.8, 57.2, 53.9, 53.7, 47.3, 32.5, 28.0, 27.5, 26.3, 22.8. HRMS m/z calcd. for C25H42ClN2O5 485.2782, found 485.2775. [α]25D+5.3° (c=1.00, CHCl3).

Provenance & Evidence