Reaktionsschritte
To an oven dried, two-necked flask (250 mL) under nitrogen and protected from light was added Cp2ZrCl2 (5.2 g, 20.3 mmol, 2 eq), dry THF (30 mL), and 1M lithium triethylborohydride (Super Hydride) in THF (20 mL, 20 mmol, 1.9 eq). The mixture was stirred for 1 h where the alkyne 3 (1.97 g, 10.2 mmol, 1 eq) was added. After 30 min, iodine (2.57 g, 20.3 mmol, 2 eq) was added and the reaction mixture was stirred for 30-40 min while protected from light. The reaction was quenched by diluting with ethyl acetate/hexane (1:1, 50 mL). The diluted mixture was then washed twice with saturated solution of sodium bicarbonate (150 mL) and the combined aqueous layers were extracted with ethyl acetate/hexane mixture (1:1). 10% aqueous sodium thiosulphate (100 mL) was used to wash the combined organic phases followed by brine (100 mL), dried over sodium sulfate, filtered, concentrated to yellowish slurry which was purified by silica gel column chromatography using 100% hexane as eluent (silica gel was pretreated with 2.5% v/v triethylamine) to afford 4 as white amorphous crystals (1.80 g, 55%): mp 64-660° C. 1H NMR (300 MHz, CDCl3): 7.64-7.52 (m, 4H, HAr), 7.49-7.41 (m, 2H), 7.38-7.32 (m, 1H, HAr), 7.13-7.01 (m, 3H, HAr), 5.74 (s, 1H, CH═CH, J=12.2 Hz) ppm; 13C NMR (75 MHz, CDCl3): 155.5, 150.3, 140.3, 137.0, 128.9, 128.4, 127.2, 126.9, 117.5, 57.9 ppm; IR (cm−1): 3316, 3077, 3034, 2960, 2924, 2874, 2174, 1643, 1623, 1601, 1515, 1485, 1330, 1307, 1226, 1186, 1173, 1093, 1008, 919, 854, 837, 697, 579, 549.
