Diisopropylamine → Isobutyl 2-(4-fluorophenyl)-3-nitro-propyl(methyl)phosphinate

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Reaction Steps

To a solution of 8.1 g of diisopropylamine in 50 ml of dry tetrahydrofuran at -78° C. under an atmosphere of nitrogen are added 50.0 ml of a 1.6M solution of n-butyllithium in hexane. This solution is then stirred for a period of 10 minutes at this temperature, after which time a solution of 10.0 g of isobutyl P,P-dimethyl-phosphinate is added. This mixture is stirred at -78° C. for a period of 1 hour, after which time a solution of 11.1 g of trans-1-(4-fluorophenyl)-2-nitro-ethene in 50 ml of tetrahydrofuran is added. This mixture is then allowed to warm to room temperature when 40 ml of a saturated ammonium chloride solution is added. The aqueous layer is then extracted with 2×25 ml of diethyl ether and the organic extracts are combined and dried over magnesium sulphate. The solvent is then evaporated under reduced pressure and the crude product purified by chromatography on silica gel using 5 parts ethyl acetate to 1 part ethanol as eluent. The fractions containing product are combined and concentrated under reduced pressure to give isobutyl 2-(4-fluorophenyl)-3-nitro-propyl-(methyl)phosphinate as a viscous oil, 31P-N.M.R. spectrum: δ=+51.0 and +50.6 ppm (CDCl3).

Provenance & Evidence