Iodine → 5-((Tert-butyldimethylsilyl)oxy)-1-(2,4-difluoro-5-(pyrimidin-5-yl)phenyl)-2-methylenepentan-1-one

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Reaction Steps

A solution of ((4-bromopent-4-en-1-yl)oxy)(tert-butyl)dimethylsilane (prepared following the procedures of Rostami, Organic Letters, 2007), 9(4), 703-706) (3.30 g, 11.81 mmol) in THF (25 mL) was added to a flask filled with magnesium (0.574 g, 23.62 mmol) and iodine (0.092 g, 0.363 mmol), and the resulting dark brown suspension was stirred at rt for 15 min and then heated under reflux for 45 min. The color changed from brown to deep reddish and the color of iodine faded 10 min under reflux. Eventually, the color of the reaction mixture turned to grey. This regent was cooled to rt and then added to a suspension of 2,4-difluoro-5-(pyrimidin-5-yl)benzaldehyde (Preparation 15, 2 g, 9.08 mmol) in THF (14 mL), and the reaction mixture was stirred at rt for 12 h. Water was added and the aqueous layer was extracted with EtOAc (×3). The combined organic layers were washed with brine, dried over anhydrous sodium sulfate, and filtered, and the filtrate was evaporated in vacuo to give the crude product. The crude product was purified by silica gel chromatography eluting with 0-35% EtOAc/Hexane to give 5-((tert-butyldimethylsilyl)oxy)-1-(2,4-difluoro-5-(pyrimidin-5-yl)phenyl)-2-methylenepentan-1-one (0.95 g, 2.270 mmol, 24.99% yield). 1H NMR (500 MHz, CHLOROFORM-d) δ 9.27 (s, 1H), 8.93 (d, J=1.4 Hz, 2H), 7.59 (dd, J=8.2, 7.3 Hz, 1H), 7.20-7.03 (m, 1H), 6.04 (s, 1H), 5.78 (d, J=1.8 Hz, 1H), 3.70 (t, J=6.3 Hz, 2H), 2.62-2.41 (m, 2H), 1.85-1.70 (m, 2H), 0.93 (m, 9H), 0.09 (m, 6H).

Provenance & Evidence