Cesium carbonate → 3-(Tert-butoxycarbonylamino-methyl)-5-methyl-hexanoic acid 1-isobutyryloxy-ethyl ester

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Reaction Steps

Cesium carbonate (0.365 g, 1.12 mmol) was dissolved in methanol (5 mL) and S-form of compound 4 (0.500 g, 1.28 mmol) was added. The solution was stirred for 4 hours at room temperature and concentrated to dryness. The residue was diluted with CH3CN (7.5 mL), and compound 14 (0.945 g, 3.56 mmol) and CH3CN (5 mL) were then added. After stirring overnight at room temperature, the reaction solution was filtered and concentrated to give 1 g of the crude product, which was then purified by chromatography on a column of silica gel (70-230 mesh, elution: EA/Hexane=1:4). Compound 3-(tert-butoxycarbonylamino-methyl)-5-methyl-hexanoic acid 1-isobutyryloxy-ethyl ester 15 (0.13 g) was obtained with 27% yield. 1HNMR (CDCl3, 500 MHz) δ0.87-0.92 (m, 6H), 1.10-1.21 (m, 2H), 1.55 (d, J=5 Hz, 6H), 1.44 (s, 9H), 1.48 (d, J=5.5 Hz, 3H), 1.52-1.59 (m, 2H), 2.06-2.12 (m, 1H), 2.28-2.35 (m, 2H), 2.49-2.57 (m, 1H), 2.93-3.06 (m, 1H), 3.12-3.22 (m, 1H), 4.62-4.73 (m, 1H), 6.84 (q, J=5.5 Hz, 1H).

Provenance & Evidence