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Sodium hydride (60% in mineral oil, 3.38 g, 84.4 mmol, 1.1 eq.) was combined with hexane (40 mL), and the mixture was subjected to rapid mechanical stirring for 5 minutes. The solids were allowed to settle and the hexane was removed. This procedure was repeated twice to remove mineral oil. N,N-Dimethylformamide (59 mL, 1.3 M) was added and the mixture was cooled to 0° C.; methyl iodide (5 mL; 81 mmol, 1.05 eq.) was then added drop-wise, followed by drop-wise addition of a solution of #9 (19.6 g, 76.8 mmol, 1 eq.) in N,N-dimethylformamide (59 mL) over 5 minutes, while keeping the temperature between 0° C. and 5° C. The reaction was stirred at 0° C. for 2 hours. The reaction was quenched with saturated aqueous ammonium chloride solution (150 mL), poured into aqueous sodium chloride solution (5% wt, 300 mL), and the mixture was extracted with ethyl acetate (3×50 mL). The combined organic layers were washed with 10% aqueous sodium chloride solution (2×300 mL), washed with water (200 mL), and concentrated in vacuo. The resulting water-wet oil was reconcentrated from ethyl acetate (150 mL) and purified by silica gel chromatography (Gradient: 2% to 10% ethyl acetate in heptane) to afford #10 (15.0 g, 73%) as a colorless oil. 1H NMR (400 MHz, CDCl3), presumed to be a mixture of rotamers: δ 5.60-5.83 (m, 1H), 4.91-5.06 (m, 2H), 3.81-3.95 (br m, 1H), 3.43 (s, 3H), 3.36-3.61 (m, 2H), 3.19-3.31 (m, 1H), 2.09-2.21 (m, 1H), 1.86-2.02 (br m, 2H), 1.62-1.85 (br m, 2H), 1.47 and 1.49 (2 s, total 9H), 1.09 (d, J=6.6 Hz, 3H).

1. customthe hexane was removed
2. customto remove mineral oil
3. additionN,N-Dimethylformamide (59 mL, 1.3 M) was added
4. customthe temperature between 0° C. and 5° C
5. stirringThe reaction was stirred at 0° C. for 2 hours
6. customThe reaction was quenched with saturated aqueous ammonium chloride solution (150 mL)
7. additionpoured into aqueous sodium chloride solution (5% wt
8. extraction300 mL), and the mixture was extracted with ethyl acetate (3×50 mL)
9. washThe combined organic layers were washed with 10% aqueous sodium chloride solution (2×300 mL)
10. washwashed with water (200 mL)
11. concentrationconcentrated in vacuo
12. custompurified by silica gel chromatography (Gradient: 2% to 10% ethyl acetate in heptane)