Water → HCID 22850139, Verbindung

To a solution of 4.55 g of isobutyl O-trimethylsilyl-P-methyl-phosphonite in 100 ml of dry tetrahydrofuran are added 5.0 g of (2R)-glycidyl tosylate followed by 0.2 g of dry zinc chloride. The mixture is heated to reflux for a period of 3 hours under an inert gas atmosphere. The mixture is allowed to cool to room temperature, the solvent is evaporated under reduced pressure, the residue dissolved in 50 ml of chloroform, and this is stirred vigorously with 25 ml of water for a period of 0.5 hours. The organic layer is separated, dried over magnesium sulphate and the solvent is removed under reduced pressure. The residue is chromatographed on silica gel using 5 parts of ethyl acetate and 1 part of ethanol as eluent. There is obtained isobutyl P-[2(S)-hydroxy-3-tosyloxy-propyl]-P-methyl-phosphinate as a viscous oil, 31P-NMR spectrum: δ=+54.5 and +53.4 ppm (CDCl3), [α]D25 =+6.5(c=0.54% in ethanol). A solution of 3.32 g of isobutyl P-[2(S)-hydroxy-3-tosyloxy-propyl]-P-methyl-phosphinate and 1.19 g of sodium azide in 25 ml of dry dimethylformamide is heated to a temperature of 120° for a period of 3 hours, under an inert gas atmosphere. The reaction mixture is allowed to cool to room temperature, poured onto 50 ml of water and extracted twice with 100 ml of ethyl acetate. The organic extract is dried over magnesium sulphate and the solvent removed under reduced pressure. The residue is chromatographed on silica gel using 5 parts of ethyl acetate to 1 part of ethanol as eluent. There is obtained isobutyl P-[3-azido-2(S)-hydroxy-propyl]-P-methyl-phosphinate as a viscous oil, 1P-NMR spectrum: δ=+54.8 and +53.7 ppm (CDCl3), [α]D25 =+18.6(0.56% in ethanol