Sulfuric acid magnesium salt (1:1) → HCID 86741372, compound

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Reaction Steps

To a solution, stirred at room temperature, of 0.9 g (5.4 mmol) of 2,4-dimethoxybenzylamine in 100 ml of methylene chloride are added 3 g of molecular sieve 4 Å and, after 20 minutes, 0.7 g (5.4 mmol) of isopropylidene-L-glyceraldehyde and 5 g of anhydrous magnesium sulphate. The mixture is subsequently stirred at room temperature for a further 1 hour. The organic solution of isopropylidene-L-glyceraldehyde (2,4-dimethoxybenzyl)imine obtained is cooled to -20° C. under argon and treated while stirring with 0.88 ml (5.4 mmol) of triethylamine. A solution of 1.25 g (5.6 mmol) of phthaloylglycyl chloride in 20 ml of dry methylene chloride is then added dropwise within 1 hour and subsequently the mixture is stirred at room temperature overnight. The mixture is washed three times with 100 ml of water each time and with 100 ml of sodium chloride solution and then dried over sodium sulphate. After evaporation, the residue is chromatographed on silica gel (230-400 mesh) while eluting with n-hexane/ethyl acetate (1:1). There are obtained 1.77 g (70%) of N-[(3S,4S)-cis-1-(2,5-dimethoxybenzyl)-4-[(R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2-oxo-3-azetidinyl]phthalimide in the form of a foam; [α]D =+41° (c=0.8 in chloroform); MS: 466 (M+).

Provenance & Evidence