523 mg; 510 mg |
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Mg shavings (939 mg, 38.6 mmol) are suspended in Et2O (20 ml)and <strong>[4117-09-3]1-bromohept-6-ene</strong> (3.385 g, 19.115 mmol) is added dropwise. Thereaction mixture is stirred at RT for 3 h. Then the Grignard reagent isadded to EtOSiCl3 (945 mg, 5.150 mmol), dissolved in Et2O (20 ml), at 0 C via cannula. The reaction mixture is allowed to warm to RT andthen stirred for 2 h. Subsequently, 20 ml of the solvent are removed invacuo and 20 ml of hexanes are added to precipitate the salts formedduring the Grignard reaction. The reaction mixture is ffiltered throughcelite and the solvent removed in vacuo. The crude product is purifiedby column chromatography (SiO2, hexanes : ethylacetate=8 : 1) and 2 from the first fraction. The colorless liquid 2d (510 mg, 0.778 mmol) isisolated from the second fraction as the major product in 30% yield. Tris(hept-6-enyl)ethoxysilane 21H NMR (CDCl3, 499.7 MHz): X (ppm)=5.81 (ddt,3Jtrans(1H-1H)=16.9, 3 Hz, 3Jcis(1H-1H) =10.2 Hz, 3J(1H-1H) =6.7 Hz,3H, H6), 4.99 (ddt, 3Jtrans(1H-1H) =17.1 Hz, 2J(1H-1H) =2.1 Hz, 4J(1H-1H) =1.5 Hz, 3H, H7Z), 4.93 (ddt, 3Jcis(1H-1H) =10.2 Hz, 2J(1H-1H) =2.3 Hz, 4J(1H-1H) =1.1 Hz, 3H, H7E), 3.65 (q, 3J(1H-1H)=6.9 Hz, 2H, H8), 2.00-2.07 (m, 6H, H5), 1.30-1.41 (m, 18H, overlappingH2, H3, H4), 1.17 (t, 3J(1H-1H) =6.9 Hz, 2H, H9), 0.56-0.61(m, 6H, H1); 13C{1H} NMR (CDCl3, 125.7 MHz): X (ppm)=139.21(C6), 114.11 (C7), 58.37 (C8), 33.73 (C5*), 33.11 (C3*), 28.57 (C4),23.02 (C2), 18.65 (C9), 13.59 (C1), *assignments interchangeable; 29Si{1H} NMR (CDCl3, 79.4 MHz): X (ppm)=15.36 (s).Hexakis(hept-6-enyl)disiloxane 2d.1H NMR (CDCl3, 499.7 MHz): X (ppm)=5.81 (ddt, 3Jtrans(1H-1H)=16.9 Hz, 3Jcis(1H-1H) =10.2 Hz, 3J(1H-1H) =6.7 Hz, 6H, H6), 4.99(ddt, 3Jtrans(1H-1H) =17.1 Hz, 2J(1H-1H) =2.1 Hz, 4J(1H-1H) =1.5 Hz,6H, H7Z), 4.93 (ddt, 3Jcis(1H-1H) =10.2 Hz, 2J(1H-1H) =2.2 Hz, 4J(1H-1H) =1.2 Hz, 6H, H7E), 2.04 (dt, 3J(1H-1H) =6.7 Hz, 3J(1H-1H)=6.6 Hz, 12H, H5), 1.30-1.43 (m, 36H, overlapping H2, H3, H4), 0.56-0.61 (m, 12H, H1); 13C{1H} NMR (CDCl3, 125.7 MHz): X(ppm)=139.16 (C6), 114.15 (C7), 33.69 (C5*), 33.01 (C3*), 28.57(C4), 22.91 (C2), 14.99 (C1), *assignments interchangeable |