Benzene → (NE,R)-N-[(2S)-2-(2,3-difluorophenyl)hex-5-enylidene]-2-methylpropane-2-sulfinamide

Beteiligte Stoffe

Reaktionsschritte

In a 500 mL round-bottomed flask was dissolved (S)-2-(2,3-difluorophenyl)hex-5-enal (3.61 g, 17.2 mmol) (freshly azeotroped with dry benzene) and (R)-2-methylpropane-2-sulfinamide (2.08 g, 17.2 mmol) in tetrahydrofuran (100 mL) to give a yellow solution. Titanium(IV) ethoxide (36.0 mL, 34.3 mmol) was added dropwise, and the mixture was stirred at rt under nitrogen for 6 h. It was transferred to a stirred solution of brine (90 mL) and a white solid was formed. This was filtered through a plug of celite and washed with ethyl acetate. The eluent was concentrated to give a tan oil. The residue was purified by flash column chromatography up to 40% ethyl acetate/hexane afforded the desired product (3.94 g, 73% for 2 steps) as a light yellow oil: 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 8.09 (d, J=4.52 Hz, 1H) 7.02-7.14 (m, 2H) 6.97 (d, J=8.28 Hz, 1H) 5.68-5.87 (m, 1H) 5.02 (d, J=13.05 Hz, 2H) 4.07-4.18 (m, 1H) 2.19 (dt, J=13.30, 6.65 Hz, 1H) 2.05-2.13 (m, 2H) 1.90-2.03 (m, 1H) 1.17 (s, 9H); 19F NMR (376 MHz, CHLOROFORM-d) δ ppm −137.55 (br. s., 1F) −142.03 (br. s., 1F); 13C NMR (101 MHz, CHLOROFORM-d) δ ppm 167.97 (s, 1C) 151.70-149.09 (m, 1C) 149.93-147.27 (m, 1C) 136.71 (d, J=9.25 Hz, 1C) 128.43 (d, J=9.25 Hz, I C) 122.99-124.42 (m, 1C) 115.88-115.68 (m, 1C) 115.37 (m, 1C) 109.63 (s, 1C) 56.77 (s, 1C) 43.94 (d, J=12.33 Hz, 1C) 30.83 (s, 1C) 30.40 (s, 1C) 21.96 (d, J=5.39 Hz, 3C).

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