Dimethyl Sulfoxide → rel-(1R,2R)-2-(4-Bromophenyl)cyclopropanecarboxaldehyde

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Reaction Steps

The above alcohol (1.07 g) was suspended in hexane (50 ml) at room temperature and cooled to -20° C. under nitrogen Diethyl zinc (ex Aldrich) (22.7 ml of a 1.1M solution in hexane) was added dropwise, followed by diiodomethane (ex Aldrich) (4.1 ml). The mixture was allowed to warm to 25° slowly, then stirred for 18 hours. Saturated ammonium chloride was added and the mixture extracted with ether. The combined ethereal extracts were washed with saturated sodium thiosulphate solution dried over magnesium sulphate and the solvents removed under vacuum. Purification by chromatography (silica, ether/hexane) gave (±)-trans-2-(4-bromophenyl)-1-hydroxymethyl cyclopropane (0.53 g). NMR 1H: 7.38(2H,d), 6.95(2H,d),3.65 (2H,d),1.8 (1H,m), 1.55 (1H,s), 1.44(1H,m), 0.95 (2H,m). p (iv) Oxalyl chloride (ex Aldrich)(0.22 ml) was dissolved in dichloromethane (3 ml) and cooled to -70° under nitrogen. Dimethylsulphoxide (ex BDH) (0.36 ml) in dichloromethane (1 ml) was added dropwise. After five minutes, the above alcohol (0.53 g) in dichloromethane (4 ml) was added and the suspension stirred at -70° for 30 minutes. Triethylamine (ex Aldrich) (1.6 ml) was added and the mixture allowed to warm to 0° over one hour. Work-up in the conventional manner gave (±)-trans-[2-(4-bromophenyl)cyclopropyl]-methanal which was used directly. NMR 1H: 9.4 (1H,d), 7.33 (2H,d), 6.9 (2H,d), 2.54(1H,m), 2.20 (1H,m), 1.0-1.9(2H,m).

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