2,6-Dibromophenol → Ethyl 3-Cyclopentene-1-carboxylate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A flame-dried 500 mL flask was charged with 2,6-dibromophenol (1.20 g, 4.76 mmol), tungsten oxychloride (0.813 g, 2.38 mmol), and anhydrous toluene (25 mL). The resulting suspension was heated at reflux under nitrogen for 1 h, and then the solvent was evaporated in vacuo. The solid residue was broken up with a spatula and dried in vacuo for 30 min. To the residue were added toluene (160 mL), Et4Pb (1.54 g, 4.76 mL), and 702 (22 g, 131.0 mmol). The mixture was heated at 90° C. under nitrogen for 1.5 h. After being cooled to r.t., the mixture was filtered through a celite, and the celite was rinsed with t-BuOMe. The combined filtrates were washed with 1% NaOH soln, water, and brine, and concentrated by evaporation at reduced pressure. The residue was distilled (37-38° C./1 Torr) to give 13.06 g (71%) of 703 as a colorless liquid. 1H NMR (400 MHz, CDCl3) δ 5.67 (s, 2H, CH═CH), 4.14 (q, 2H, J= 7.2 Hz, OCH2), 3.11 (pentuplet, J=7.6 Hz, 1H, CH), 2.65 (d, J=7.6 Hz, 4H, 2 CH2), 1.27 (t J=7.2 Hz, 3H, CH3).

Herkunft & Nachweise