Compound 7

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InChIKey HKQWAHRPULKTCC-UHFFFAOYSA-N

Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

Compound 7 was prepared according to a modified literature procedure (Hoheisel, T. N. & Frauenrath, H. A convenient Negishi protocol for the synthesis of glycosylated oligo(ethynylene)s. Org. Lett. 10, 4525-4528, (2008)): MeLi · LiBr complex (26.62 mL, 2.2 M in Et₂O, 58.56 mmol) was added to 1,4-bis(trimethylsilyl)butadiyne (11.75 g, 60.44 mmol) in THF (80 mL) at 0 °C, and the resulting mixture was stirred for 30 minutes. Then ZnCl₂ (86.3 mL, 0.7 M in THF, 60.41 mmol) was added at 0 °C, and the resulting mixture was again stirred for 30 min. In another flask, n-butyl lithium (1.6 mL, 2.5 M in n-hexane, 4.00 mmol) was added to a suspension of PdCl₂(dppf) · DCM (599 mg, 0.73 mmol) in toluene (400 mL) at 0 °C until an orange solution was obtained. Then, the zinc diacetylide solution was transferred into the catalyst solution via a cannula, and 1-bromotetradec-1-yne 6 (10.04 g, 36.74 mmol) was added simultaneously with a syringe at 0 °C. The mixture was stirred for 3 d while warming up to room temperature, before it was diluted with Et₂O, washed twice with saturated NH₄Cl solution and once with saturated NaCl solution. The organic phase was dried over MgSO₄, and concentrated in vacuo. Then the mixture was diluted with MeCN, extracted with pentane (3 × 200 mL), and the combined pentane phases were evaporated to give a brown liquid. Column chromatography (silica gel; n-heptane) yielded 7 (10.92 g, 95%) as an orange oil. ¹H NMR (500.13 MHz, CDCl₃): δ = 2.29 (t, J = 7.0 Hz, 2H, CCCH₂), 1.74-1.44 (m, 2H, CCCH₂CH₂), 1.43–1.20 (m, 18H, (CH₂)₉CH₃), 0.88 (t, J = 6.7 Hz, 3H, (CH₂)₁₁CH₃), 0.19 (s, 9H, Si(CH₃)₃). ¹³C NMR (125.77 MHz, CDCl₃): δ = 88.6, 85.6, 81.3, 65.7, 62.7, 60.1 (6 C≡C), 32.1, 29.8, 29.8, 29.7, 29.6, 29.5, 29.2, 29.0, 28.2, 22.9 ((CH₂)₁₀CH₃), 19.6 (CCCH₂), 14.3 (CH₃), –0.3 (Si(CH₃)₃). m.p.: –2-0 °C. HRMS (EI): calcd for C₂₀H₃₁Si ([M–Me]⁺) 299.2195; found: 299.2189. R_f: 0.65 (n-heptane).