Compound 4

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InChIKey FKYYANICVKHNHI-UHFFFAOYSA-N

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

Compound 4 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 (17.9 mL, 2.2 m in Et₂O, 39.26 mmol) was added to 1,4-bis(trimethylsilyl)butadiyne (7.82 g, 40.24 mmol) in THF (50 mL) at 0 °C, and the resulting mixture was stirred for 30 minutes. Then ZnCl₂ (57.5 mL, 0.7 m in THF, 40.24 mmol) was added at 0 °C, and the resulting mixture was again stirred for 30 min. In another flask, 4-tritylphenyl 6-bromohex-5-ynoate 3 (10.0 g, 19.63 mmol) and PdCl₂(dppf) · DCM (1.60 g, 1.96 mmol) were mixed in toluene (300 mL). The two solutions were combined at 0 °C, and the flask was wrapped with aluminum foil. The mixture was stirred for 16 h while warming up to room temperature, before it was diluted with Et₂O, washed three times with saturated NH₄Cl solution and once with saturated NaCl solution. The organic phase was dried over Na₂SO₄ and concentrated in vacuo. Column chromatography (silica gel; DCM/n-heptane 1:1) yielded 4 (7.7 g, 71%) as a light brown solid. ¹H NMR (400 MHz, CDCl₃): δ = 7.30-7.16 (m, 17H), 7.01-6.95 (m, 2H), 2.69 (t, J = 7.3 Hz, 2H), 2.47 (t, J = 6.9 Hz, 2H), 1.98 (p, J = 7.0 Hz, 2H), 0.20 (s, 9H). ¹³C NMR (101 MHz, CDCl₃): δ = 171.4, 148.6, 146.7, 144.5, 132.3, 131.2, 127.7, 126.1, 120.4, 88.3, 86.1, 79.3, 66.7, 64.7, 62.3, 60.6, 33.0, 23.2, 19.0, –0.3. HRMS (MALDI): calcd for C₃₈H₃₄O₂Si: 573.2219 ([M+Na]⁺); found: 573.2201. R_f: 0.33 (DCM/n-heptane 1:1).