EXPERIMENTAL Triethylsilyloxy alcohol 5 b. To a solution of diol 5a (3.16 g, 13.4 mmol) and DMAP (70 mg, 0.57 mmol) in CH₂Cl₂ (65 mL) at room temperature was added triethylamine (3.7 mL, 26.6 mmol) followed by dropwise addition of TESCI (2.7 mL, 16.1 mmol). After 1.75 h, the reaction mixture was diluted with 150 mL of hexane, then poured into 100 mL of a saturated aqueous NaHCO3 solution and 150 mL of hexane. The organic phase was washed with two 100 mL portions of saturated aqueous NaHCO3 solution and with 100 mL of water, dried over anhydrous Na2SO4, and concentrated under reduced pressure to give 4.88 g of crude triethylsilyloxyalcohol 5b. An analytical sample was obtained by plug filtration through a short pad of silica gel washing with hexane and then eluting the pure compound 5b (colorless oil) with 5% ethyl acetate in hexane. 5b: 1H NMR (300 MHz, CDC13) 8 0.61 (q, J = 7.7 Hz, 6H, TES CH2), 0.89 (s, 3H, CH3 16), 0.96 (t, J = 7.7 Hz, 9H, TES CH3), 1.03 (d, J = 7.1 Hz, 3H, CH3 19), 1.07 (s, 3H, CH3 17), 1.23 (d, J = 14.3 Hz, 1H, H2α), 1.56 (dd, J= 6.0, 6.0 Hz, 1H, H7), 1.76 (ddd, J= 5.0, 10.4, 14.6 Hz, 1H, H9), 1.90 (ddd, J = 2.2, 7.7, 14.6 Hz, 1H, H9), 1.96 (m, 1H, H14α), 2.37 (m, 2H, H2ẞ, H14ẞ), 2.51 (ddd, J = 7.1, 7.7, 10.4 Hz, 1H, H8a), 2.94 (s, 1H, OH 3), 4.21 (dd, J = 2.2, 5.0 Hz, 1H, H10), 5.43 (dd, J = 2.8, 2.8 Hz, 1H, H13). 13C NMR (75 MHz, CDCl3) 8 (ppm) 4.8 (TES CH₂), 6.7 (TES CH3), 15.02 (CH3 19), 23.0 (CH3 17), 26.2 (CH3 18), 28.0 (CH3 16), 33.6 (C14), 41.5 (C8), 44.2 (C2), 45.0 (C1), 45.2 (C15), 45.8 (C9), 69.6 (C11), 74.9 (C10), 96.0 (C3), 123.0 (C13), 143.7 (C12); IR (CHCl3) v 3530, 2970, 2930, 2900, 1460, 1340, 1140, 1100, 1080, 1045, 1010, 970, 915, 650 cm-1; MS (CI) 351 (M+1, 58), 333 (100), 219 (34). In 1994, Robert A. Holton and his group of researchers presented the first total synthesis of the very important antitumor agent Taxol. This synthesis contained dozens of reaction steps, and was described in several publications. One such publication (J. Am. Chem. Soc. 1994, 116, 1597-1598) describes the experimental procedures and spectral data in the supplementary material associated with the article. Many of the techniques used are the same ones you are learning in this course. An excerpt from that material is included below. Read this excerpt and answer the following questions (you do not need to look up the article, but you do have access to the article and the supplementary material if you are interested).

EXPERIMENTAL Triethylsilyloxy alcohol 5 b. To a solution of diol 5a (3.16 g, 13.4 mmol) and DMAP (70 mg, 0.57 mmol) in CH₂Cl₂ (65 mL) at room temperature was added triethylamine (3.7 mL, 26.6 mmol) followed by dropwise addition of TESCI (2.7 mL, 16.1 mmol). After 1.75 h, the reaction mixture was diluted with 150 mL of hexane, then poured into 100 mL of a saturated aqueous NaHCO3 solution and 150 mL of hexane. The organic phase was washed with two 100 mL portions of saturated aqueous NaHCO3 solution and with 100 mL of water, dried over anhydrous Na2SO4, and concentrated under reduced pressure to give 4.88 g of crude triethylsilyloxyalcohol 5b. An analytical sample was obtained by plug filtration through a short pad of silica gel washing with hexane and then eluting the pure compound 5b (colorless oil) with 5% ethyl acetate in hexane. 5b: 1H NMR (300 MHz, CDC13) 8 0.61 (q, J = 7.7 Hz, 6H, TES CH2), 0.89 (s, 3H, CH3 16), 0.96 (t, J = 7.7 Hz, 9H, TES CH3), 1.03 (d, J = 7.1 Hz, 3H, CH3 19), 1.07 (s, 3H, CH3 17), 1.23 (d, J = 14.3 Hz, 1H, H2α), 1.56 (dd, J= 6.0, 6.0 Hz, 1H, H7), 1.76 (ddd, J= 5.0, 10.4, 14.6 Hz, 1H, H9), 1.90 (ddd, J = 2.2, 7.7, 14.6 Hz, 1H, H9), 1.96 (m, 1H, H14α), 2.37 (m, 2H, H2ẞ, H14ẞ), 2.51 (ddd, J = 7.1, 7.7, 10.4 Hz, 1H, H8a), 2.94 (s, 1H, OH 3), 4.21 (dd, J = 2.2, 5.0 Hz, 1H, H10), 5.43 (dd, J = 2.8, 2.8 Hz, 1H, H13). 13C NMR (75 MHz, CDCl3) 8 (ppm) 4.8 (TES CH₂), 6.7 (TES CH3), 15.02 (CH3 19), 23.0 (CH3 17), 26.2 (CH3 18), 28.0 (CH3 16), 33.6 (C14), 41.5 (C8), 44.2 (C2), 45.0 (C1), 45.2 (C15), 45.8 (C9), 69.6 (C11), 74.9 (C10), 96.0 (C3), 123.0 (C13), 143.7 (C12); IR (CHCl3) v 3530, 2970, 2930, 2900, 1460, 1340, 1140, 1100, 1080, 1045, 1010, 970, 915, 650 cm-1; MS (CI) 351 (M+1, 58), 333 (100), 219 (34). In 1994, Robert A. Holton and his group of researchers presented the first total synthesis of the very important antitumor agent Taxol. This synthesis contained dozens of reaction steps, and was described in several publications. One such publication (J. Am. Chem. Soc. 1994, 116, 1597-1598) describes the experimental procedures and spectral data in the supplementary material associated with the article. Many of the techniques used are the same ones you are learning in this course. An excerpt from that material is included below. Read this excerpt and answer the following questions (you do not need to look up the article, but you do have access to the article and the supplementary material if you are interested).

Macroscale and Microscale Organic Experiments

7th Edition

ISBN:9781305577190

Author:Kenneth L. Williamson, Katherine M. Masters

Publisher:Kenneth L. Williamson, Katherine M. Masters

Chapter4: Recrystallization

Section: Chapter Questions

Problem 1Q

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